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| 19-5063; Rev 1; 3/10 TION KIT EVALUA BLE VAILA A 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring General Description The MAX8900_ is a high-frequency, switch-mode charger for a 1-cell lithium ion (Li+) or lithium polymer (Li-Poly) battery. It delivers up to 1.2A of current to the battery from 3.4V to 6.3V (MAX8900A) or 3.4V to 8.7V (MAX8900B). The 3.25MHz switch-mode charger is ideally suited to small portable devices such as headsets and ultra-portable media players because it minimizes component size and heat. Several features make the MAX8900_ perfect for highreliability systems. The MAX8900_ is protected against input voltages as high as +22V and as low as -22V. Battery protection features include low voltage prequalification, charge fault timer, die temperature monitoring, and battery temperature monitoring. The battery temperature monitoring adjusts the charge current and termination voltage as described in the JEITA* specification for safe use of secondary lithium-ion batteries. Charge parameters are easily adjustable with external components. An external resistance adjusts the charge current from 50mA to 1200mA. Another external resistance adjusts the prequalification and done current thresholds from 10mA to 200mA. The done current threshold is very accurate achieving Q1mA at the 10mA level. The charge timer is adjustable with an external capacitor. The MAX8900_ is available in a 0.4mm pitch, 2.44mm x 2.67mm x 0.64mm WLP package. Features S 3.25MHz Switching Li+/Li-Poly Battery Charger S JEITA Battery Temperature Monitor Adjusts Charge Current and Termination Voltage S 4.2V 0.5% Battery Regulation Voltage (Alternate 4.1V Target Available on Request) S Adjustable Done Current Threshold Adjustable from 10mA to 200mA 1mA Accuracy at 10mA S High-Efficiency and Low Heat S Uses a 2.0mm x 1.6mm Inductor S Positive and Negative Input Voltage Protection (22V) S Up to +20V Operating Range (Alternate OVLO Ranges Available on Request) S Supports No-Battery Operation S Fault Timer S Charge Status Outputs S 2.44mm x 2.67mm x 0.64mm Package MAX8900A/MAX8900B Simplified Applications Circuit 1FH Applications USB Charging Headsets and Media Players Smartphones Digital Cameras GPS, PND eBook VIN (-22V TO +22V) 0.47FF 25V 0603 BST LX IN CS BAT PGND 2.2FF 6.3V 0603 SYSTEM LOAD Ordering Information PART TEMP PINRANGE PACKAGE -40NC to +85NC 30 WLP OFF OPTIONS VOVLO = 6.5V T1 = 0NC 2-pin status indicators VOVLO = 9.0V T1 = -15NC 3-pin status indicators 1.0FF 6.3V 0402 ON STAT1 STAT2 STAT3 CEN PVL INBP CT MAX8900_ AVL GND THM T Li+/ Li-POLY MAX8900AEWV+T 0.47FF 25V 0603 SETI DNI -40NC to MAX8900BEWV+T +85NC 30 WLP +Denotes a lead(Pb)-free/RoHS-compliant package. T = Tape and reel. Ordering Information continued at end of data sheet. *JEITA (Japan Electronics and Information Technology Industries Association) standard, "A Guide to the Safe Use of Secondary Lithium Ion Batteries in Notebook-type Personal Computers" April 20, 2007. _______________________________________________________________ Maxim Integrated Products 1 For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com. 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B Table of ConTenTs Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Electrical Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Typical Operating Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Pin Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Pin Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Detailed Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Control Scheme. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Soft-Start . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Setting the Fast-Charge Current (SETI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Setting the Prequalification Current and Done Threshold (DNI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Charge Enable Input (CEN) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Charger States . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Charger Disabled State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Dead-Battery State. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Dead Battery + Prequalification State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Prequalification State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Fast-Charge Constant Current State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Fast-Charge Constant Voltage State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Top-Off State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Done State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Timer Fault State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Battery Hot/Cold State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 VIN Too High State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Charge Timer (CT) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Thermal Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Thermistor Monitor (THM) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Thermal Foldback . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Thermal Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 PVL and AVL Regulator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Charge Status Outputs (3 Pin) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Charge Status Outputs (2 Pin + > T4). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Inductor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 BAT Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 INBP Capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Other Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Applications Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Dynamic Charge Current Programming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 No-Battery Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 2 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring Table of ConTenTs (continued) Charge-Source Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Charge-Source Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Inductive Kick. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 Overvoltage and Reverse Voltage Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 PCB Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Chip Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Package Information. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 Revision History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 MAX8900A/MAX8900B lisT of figures Figure 1. Applications Circuit: Single SETI Resistor, Status Indicators Connected to LEDs . . . . . . . . . . . . . . . . . . . . 15 Figure 2. Applications Circuit: Multiple Charge Rates Managed by P to Be USB Compliant, Status Indicators Connected to a P . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Figure 3. Functional Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Figure 4. Fast-Charge Current vs. RSETI (www.maxim-ic.com/tools/other/software/MAX8900-RSETI.XLS) . . . . 18 Figure 5. Prequalification Current and Done Threshold vs. RDNI (www.maxim-ic.com/tools/other/software/ MAX8900-DNI.XLS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Figure 6. Li+/Li-Poly Charge Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Figure 7. Charger State Diagram (3-Pin Status) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Figure 8. Charger State Diagram (2-Pin Status). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 Figure 9. Charge Times vs. CCT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Figure 10. JEITA Battery Safety Regions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Figure 11. Thermistor Monitor Detail. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Figure 12. Charge Current vs. Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 Figure 13. Calculated Fast-Charge Current vs. Dropout Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 Figure 14. Power PCB Layout Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Figure 15. Recommended Land Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 Figure 16. Bump Cross Section and Copper Pillar Detail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 lisT of Tables Table 1. 2.44mm x 2.67mm x 0.64mm, 0.4mm Pitch WLP Thermal Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Table 2. Trip Temperatures for Different Thermistors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Table 3. 3-Pin Status Output Truth Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Table 4. 2-Pin Status Output Truth Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 Table 5. Recommended Inductor Selection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 Table 6. Recommended Inductor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 3 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B ABSOLUTE MAXIMUM RATINGS IN to PGND.............................................................-22V to +22V INBP to PGND .......................................... (VBAT - 0.3V) to +22V IN to INBP..............................................................-30V to +1.2V STAT1, STAT2 to GND ..........................................-0.3V to +30V BST to PGND.........................................................-0.3V to +36V BST to LX..............................................................-0.3V to +6.0V BST to PVL ............................................................-0.3V to +30V PVL, BAT, CS to PGND ........................................-0.3V to +6.0V AVL, STAT3, CEN, THM to GND ..........................-0.3V to +6.0V PVL to AVL ...........................................................-0.3V to +0.3V CT to GND .................................................-0.3V to (AVL + 0.3V) SETI, DNI to GND .................................... -0.3V to (VBAT + 0.3V) PGND to GND ......................................................-0.3V to +0.3V IN Continuous Current................................................... 2.4ARMS LX Continuous Current (Note 1) .................................... 1.6ARMS CS Continuous Current ................................................ 1.3ARMS BAT Continuous Current ............................................... 1.3ARMS Continuous Power Dissipation (TA = +70NC) 30-Bump WLP (derate 20.4mW/NC above +70NC)....1616mW Operating Temperature Range .......................... -40NC to +85NC Junction Temperature ...................................... -40NC to +150NC Storage Temperature Range............................ -65NC to +150NC Soldering Temperture (reflow) ........................................+260NC Note 1: LX has an internal clamp diode to PGND and INBP. Applications that forward bias these diodes should take care not to exceed the power dissipation limits of the device. Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN = 6V, VBAT = 4V, RSETI = 2.87kI, RDNI = 3.57kI, VTHM = VAVL/2, circuit of Figure 1, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2) PARAMETER GENERAL Withstand voltage IN Input Voltage Range (Note 3) IN Undervoltage Threshold IN to BAT Shutdown Threshold IN Overvoltage Threshold (Note 3) IN Supply Current LX High-Side Resistance LX Low-Side Resistance LX Leakage Current BST Leakage Current Current-Sense Resistor IN to BAT Dropout Resistance Switching Frequency RSNS RIN2BAT fSW VIN VUVLO VIN2BAT VOVLO Operating voltage MAX8900B MAX8900A -20 3.4 3.4 3.1 0 8.80 6.35 3.2 15 9.00 6.50 1 20 0.04 0.10 0.15 LX = GND or IN VBST - VLX = 6V VBAT = 2.6V Calculation estimates a 40mI inductor resistance (RL), RIN2BAT = RIN2INBP + RHS + RL + RSNS VBAT = 2.6V TA = +25NC TA = +85NC TA = +25NC TA = +85NC 0.01 0.1 0.01 0.1 0.045 0.3 3.25 10 10 0.2 I I FA FA I I MHz +20 8.7 6.3 3.3 30 9.20 6.65 2 mA V V V mV V SYMBOL CONDITIONS MIN TYP MAX UNITS VIN falling, 400mV hysteresis (Note 4) When charging stops, VIN falling, 200mV hysteresis VIN rising 0.40V hysteresis (MAX8900B) 0.26V hysteresis (MAX8900A) Charger enabled, no switching IIN RHS RLS Charger enabled, f = 3.25MHz, VIN = 6V Charger disabled, CEN = high 4 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring ELECTRICAL CHARACTERISTICS (continued) (VIN = 6V, VBAT = 4V, RSETI = 2.87kI, RDNI = 3.57kI, VTHM = VAVL/2, circuit of Figure 1, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2) PARAMETER Minimum On-Time Maximum On-Time Minimum Off-Time SYMBOL tON-MIN tON-MAX tOFF TA = +25NC, VTHM between T1 and T3 IBAT = 0mA, MAX8900A/ MAX8900B (Figure 10) TA = -40NC to +85NC, VTHM between T1 and T3 TA = +25NC, VTHM between T3 and T4 (Note 5) TA = -40NC to +85NC, VTHM between T3 and T4 (Note 5) Charger Restart Threshold (Note 6) BAT Prequalification Lower Threshold (Figure 6) BAT Prequalification Upper Threshold (Figure 6) (Note 3) VRSTRT VPQLTH VPQUTH VTHM between T1 and T3 VTHM between T3 and T4 VBAT rising,180mV hysteresis VBAT rising, 180mV typical hysteresis, MAX8900A/MAX8900B RSETI = 2.87kI VTHM between T2 RSETI = 6.81kI and T4 (Figure 10) RSETI = 34.0kI VTHM between T1 and T2 (Figure 10); the fast-charge current is reduced to 50% the value programmed by RSETI (Figure 5) RSETI (Figure 5) Minimum Maximum Minimum Maximum 93 47 9.5 2.7 1166 490 99 4.179 4.158 4.055 4.034 -70 CONDITIONS MIN TYP 90 9 75 4.200 4.200 4.075 4.075 -100 -75 2.1 2.8 1190 500 101 50 50 1200 2.87 68.1 99 50 10.5 50 95 49 10 105 54 11.5 50 115 59 13 % mA 105 53 11.5 % mA 2.9 1214 510 103 % mA kI mA 4.221 4.242 V 4.095 4.100 -125 mV V V MAX UNITS ns Fs ns MAX8900A/MAX8900B BAT Regulation Voltage (Note 3) VBATREG Fast-Charge Current IFC Fast-Charge Current Set Range Fast-Charge Setting Resistor Range Done Current IDN RDNI = 3.83kI (Note 5) VTHM between T2 RDNI = 7.68kI (Note 5) and T4 (Figure 10) RDNI = 38.3kI VTHM between T1 and T2 (Figure 10); the done current threshold is reduced to 50% the value programmed by RDNI VTHM between T2 RDNI = 3.83kI (Note 5) and T4 (Figure 10), RDNI = 7.68kI (Note 5) VBAT = 2.6V RDNI = 38.3kI (Note 5) VTHM between T1 and T2 (Figure 10); the prequalification current is reduced to 50% the value programmed by RDNI Prequalification Current IPQ 5 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B ELECTRICAL CHARACTERISTICS (continued) (VIN = 6V, VBAT = 4V, RSETI = 2.87kI, RDNI = 3.57kI, VTHM = VAVL/2, circuit of Figure 1, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2) PARAMETER Done and Prequalification Current Set Range Done and Prequalification Setting Resistor Range Dead-Battery Charge Current Dead-Battery Voltage Threshold (Figure 6) BAT Leakage Current Charger Soft-Start Time (Note 3) CHARGE TIMER Prequalification Time Fast-Charge Time Top-Off Time Timer Accuracy THERMISTOR MONITOR THM Hot Shutoff Threshold (60NC) THM Hot Voltage Foldback Threshold (45NC) THM Cold Current Foldback Threshold (15NC) THM Cold Shutoff Threshold (-15NC/0NC) THM Input Leakage CHARGE ENABLE INPUT (CEN) CEN Input Voltage Low CEN Input Voltage High CEN Internal Pulldown Resistance T4 T3 T2 T1 VTHM/AVL falling, 1% hysteresis (thermistor temperature rising) VTHM/AVL falling, 1% hysteresis (thermistor temperature rising) VTHM/AVL rising, 1% hysteresis (thermistor temperature falling) VTHM/AVL rising, 1% 0NC, MAX8900A hysteresis (thermistor -15NC, MAX8900B temperature falling) THM = GND or AVL TA = +25NC TA = +85NC 21.24 32.68 57.00 71.06 81.43 -0.2 22.54 34.68 60.00 74.56 86.07 0.001 0.001 0.6 1.4 100 200 400 23.84 36.68 63.00 78.06 90.98 +0.2 %AVL %AVL %AVL %AVL tPQ tFC tTO -15 CCT = 0.1FF CCT = 0.1FF 30 180 16 +15 min min s % tSS RDNI IDBAT VDBAT VIN = 0V, VBAT = 4.2V, TA = +25NC includes LX leakage current TA = +85NC through the inductor MAX8900A, MAX8900B SYMBOL (Figure 5) (Figure 5) 0V P VBAT P VDBAT CONDITIONS Minimum Maximum Minimum Maximum MIN TYP 9.8 200 1.91 39.2 45 2.5 0.02 0.05 1.5 1 FA ms MAX UNITS mA kI mA V FA VIL VIH RCEN V V kI 6 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring ELECTRICAL CHARACTERISTICS (continued) (VIN = 6V, VBAT = 4V, RSETI = 2.87kI, RDNI = 3.57kI, VTHM = VAVL/2, circuit of Figure 1, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 2) PARAMETER STAT1 and STAT2 Output Voltage Low STAT1 and STAT2 Output High Leakage STAT3 Output Voltage Low STAT3 Output High Leakage PVL AND AVL 0 to 30mA internal load, VIN = 6V, TA = 0NC to +85NC 0 to 23mA internal load, VIN = 6V, TA = -40NC to +85NC Junction temperature when charge current is reduced The charge current is decreased 6.7% of the fast-charge current setting for every degree that the junction temperature exceeds the thermal regulation temperature Junction temperature rising, 15NC hysteresis SYMBOL ISINK = 1mA ISINK = 15mA VSTAT_= 28V ISINK = 1mA ISINK = 15mA VSTAT3 = 5.5V TA = +25NC TA = +85NC TA = +25NC TA = +85NC CONDITIONS MIN TYP 0.025 0.38 0.001 0.01 0.01 0.15 0.001 0.01 0.25 1 1 MAX 0.05 UNITS STATUS OUTPUTS (STAT1, STAT2, STAT3) V FA V FA MAX8900A/MAX8900B PVL and AVL Output Voltage 4.6 5.0 5.1 V THERMAL Thermal Regulation Temperature TREG 95 NC Thermal Regulation Gain Thermal-Shutdown Temperature TTREG TSHDN 6.7 +155 %/NC NC Note 2: Parameters are production tested at TA = +25NC. Limits over the operating temperature range are guaranteed through correlation using statistical quality control (SQC) methods. Note 3: Contact factory for alternative values. Note 4: VIN must be greater than VUVLO-RISING for the part to operate when CEN is pulled low. For example, if CEN is low and the MAX8900_ is operating with VUVLO-FALLING < VIN < VUVLO-RISING, then toggling CEN results in a nonoperating condition. Note 5: Guaranteed by design, not production tested. Note 6: When the charger is in its DONE state, it restarts when the battery voltage falls to the charger restart threshold. The battery voltage that causes a restart (VBAT-RSTRT) is VBAT-RSTRT = 4.2V - VRSTRT. For example, with the MAX8900A, VBAT-RSTRT = 4.2V - 100mV = 4.1V. 7 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B Typical Operating Characteristics (Circuit of Figure 1, VIN = 6V, VBAT = 3.6V, TA = +25NC, unless otherwise noted.) INPUT SUPPLY CURRENT vs. INPUT VOLTAGE (DISABLED, VBAT = 0V) MAX8900A toc01 INPUT SUPPLY CURRENT vs. INPUT VOLTAGE (DISABLED, VBAT = 3.6V) MAX8900A toc02 INPUT SUPPLY CURRENT vs. INPUT VOLTAGE (PREQUALIFICATION) MAX8900A VCEN = 0V VBAT = 2.6V RDNI = 3.83kI MAX8900A toc03 120 100 80 IIN (uA) VCEN = 3.0V 120 100 80 VCEN = 3.0V 120 100 80 IIN (mA) 60 40 40 20 0 -20 -30 -20 -10 0 VIN (V) 10 20 30 IIN (uA) 60 60 40 20 0 -20 -30 -20 -10 0 VIN (V) 10 20 30 VIN RISING 20 0 0 5 VIN (V) 10 15 VIN FALLING INPUT SUPPLY CURRENT vs. INPUT VOLTAGE (CHARGING AT 1.2A) 1.2 1.0 IIN (A) 0.8 0.6 0.4 0.2 0 0 5 VIN (V) 10 15 VIN RISING VIN FALLING 0.2 0 MAX8900A VCEN = 0V VBAT = 3.1V RSETI = 2.87kI MAX8900A toc04 INPUT SUPPLY CURRENT vs. INPUT VOLTAGE (VIN2BAT DETAIL) MAX8900A toc05 CHARGE CURRENT vs. BATTERY VOLTAGE 1.2 1.0 RSETI = 2.87kI RSETI = 3.40kI VCEN = 0V VIN = 6.0V MAX8900A toc06 1.4 1.2 MAX8900A 1.0 0.8 0.6 0.4 VIN RISING VIN FALLING VCEN = 0V VBAT = 4.0V RSETI = 3.01kI RL = 90mI 1.4 IBAT (A) IIN (A) 0.8 0.6 0.4 0.2 0 RSETI = 6.81kI RSETI = 34.0kI RDNI = 3.83kI 0 1 2 3 VBAT (V) 4 5 6 3.5 4.5 5.5 VIN (V) 6.5 7.5 INPUT SUPPLY CURRENT AND CHARGE CURRENT vs. INPUT VOLTAGE MAX8900A toc07 MAX8900A toc08 1.0 0.8 0.6 0.4 0.2 0 3.5 4.5 5.5 VIN (V) 6.5 MAX8900A VCEN = 0V VBAT = 4.0V RSETI = 3.01kI VIN FALLING IBAT IIN 1.008 1.006 NORMALIZED VBAT NORMALIZED VBAT 1.004 1.002 1.000 0.998 0.996 0.994 0.992 0.990 -40 -15 10 VCEN = 0V VBAT = UNCONNECTED VIN = 5.0V VTHM = VAVL/2 1.008 1.006 1.004 1.002 1.000 0.998 0.996 0.994 0.992 0.990 MAX8900B VCEN = 0V VBAT = UNCONNECTED CURRENT (A) 7.5 35 60 85 4 5 6 VIN (V) 7 8 9 AMBIENT TEMPERATURE (C) 8 MAX8900A toc09 1.2 BATTERY REGULATION VOLTAGE vs. AMBIENT TEMPERATURE 1.010 BATTERY REGULATION VOLTAGE vs. INPUT VOLTAGE 1.010 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 6V, VBAT = 3.6V, TA = +25NC, unless otherwise noted.) MAX8900A/MAX8900B SWITCHING FREQUENCY vs. INPUT VOLTAGE MAX8900A toc10 SWITCHING FREQUENCY vs. CHARGE CURRENT MAX8900A toc11 5.0 4.5 SWITCHING FREQUENCY (MHz) 6 SWITCHING FREQUENCY (MHz) 5 4 3 2 1 0 VIN = 5V, VBAT = 3V VIN = 6V, VBAT = 4V VIN = 4.5V, VBAT = 4V 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 4 8 12 16 20 VBAT = 4V VBAT = 3V MAX8900x VIN RISING VOVLO = 28V VCEN = 0V RISET = 2.87kI 24 28 0 0.2 0.4 0.6 0.8 1.0 1.2 INPUT VOLTAGE (V) CHARGE CURRENT (A) MAX8900B DC SWITCHING WAVEFORMS (IBAT = 100mA) MAX8900A toc12 MAX8900B DC SWITCHING WAVEFORMS (IBAT = 440mA) MAX8900A toc13 VOUT 20mV/div VOUT VLX 20mV/div VLX 5V/div 0V 5V/div 0V ILX 200mA/div 0A ILX 500mA/div 0A 200ns/div 200ns/div MAX8900B DC SWITCHING WAVEFORMS (IBAT = 1.2A) CHARGE CURRENT vs. AMBIENT TEMPERATURE VTHM = VAVL/2 RSETI = 2.87kI 1.0 IBAT (A) 1.2 MAX8900A toc15 MAX8900A toc14 1.4 20mV/div VOUT VLX 5V/div 0V 0.8 0.6 0.4 RSETI = 6.81kI ILX 500mA/div 0A 200ns/div 0.2 0 -40 -15 10 35 60 85 110 135 160 185 TA (C) 9 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 6V, VBAT = 3.6V, TA = +25NC, unless otherwise noted.) THM NORMAL TO COLD CURRENT FOLDBACK (T2) TO COLD SHUTOFF (T1) MAX8900A toc16 THM NORMAL TO HOT VOLTAGE FOLDBACK (T3) TO HOT SHUTOFF (T4) THRESHOLD MAX8900A toc17 60% OF AVL (T2) VTHM 74.5% OF AVL (T1) VBAT 3.6V 2V/div 1200mA (T2 < T < T3) IBAT 600mA 0mA 20ms/div 0V 1V/div VTHM 4.2V 34.7% OF AVL (T3) 4.075V 2V/div 22.5% OF AVL (T4) VBAT 10I RESISTOR LOAD 0V 2V/div 200mA/div 0A IBAT 200mA/div 0A 20ms/div CHARGER ENABLE MAX8900A toc18 EFFICIENCY vs. BATTERY VOLTAGE (CONSTANT-CURRENT MODE) 5V/div 5V/div EFFICIENCY (%) 83 81 79 77 75 73 71 69 67 65 2.5 3.0 3.5 VBAT (V) 4.0 4.5 IBAT = 100mA VIN = 5.0V MAX8900A toc19 85 VCEN VPVL VLX 5V/div IBAT 1.2A 1A/div 0A 400s/div EFFICIENCY vs. BATTERY VOLTAGE (CONSTANT-CURRENT MODE) MAX8900A toc20 EFFICIENCY vs. CHARGE CURRENT (CONSTANT-CURRENT MODE) VIN = 5.0V 90 EFFICIENCY (%) 85 80 75 70 65 0 0.5 IBAT (A) 1.0 1.5 VBAT = 3.0V VBAT = 3.6V VBAT = 4.0V MAX8900A toc21 EFFICIENCY vs. BATTERY VOLTAGE (CONSTANT-CURRENT MODE, IBAT = 1200mA) IBAT = 1200mA, RSETI = 2.87kI MAX8900A toc22 95 95 95 90 EFFICIENCY (%) 85 80 75 70 65 VIN = 5.0V 90 EFFICIENCY (%) 85 80 75 70 65 IBAT = 500mA IBAT = 800mA IBAT = 1200mA 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 VBAT (V) VIN = 5V VIN = 8V VIN = 7V VIN = 6V VIN = 8.5V 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 VBAT (V) 10 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 6V, VBAT = 3.6V, TA = +25NC, unless otherwise noted.) MAX8900A/MAX8900B EFFICIENCY vs. INPUT VOLTAGE (CONSTANT-CURRENT MODE) MAX8900A toc23 EFFICIENCY vs. CHARGE CURRENT (CONSTANT-VOLTAGE MODE) MAX8900A toc24 BATTERY + LX LEAKAGE CURRENT vs. INPUT VOLTAGE CEN = 1 VBAT = 4.0V VBAT = 3.2V 100 MAX8900A toc25 90 88 86 EFFICIENCY (%) 100 IBAT = 1200mA, RSETI = 2.87kI 1000 BATTERY LEAKAGE CURRENT (nA) VIN = 5V, VBAT = 4.2V 95 EFFICIENCY (%) 90 85 80 75 70 84 82 80 78 76 74 5 6 7 VIN (V) 8 VBAT = 4.0V VBAT = 3.6V VBAT = 3.0V 9 10 0 500 IBAT (A) 1000 1500 10 0 1 2 3 4 5 INPUT VOLTAGE (V) BATTERY + LX LEAKAGE CURRENT vs. BATTERY VOLTAGE MAX8900A toc26 BATTERY + LX LEAKAGE CURRENT vs. AMBIENT TEMPERATURE IN UNCONNECTED STAT INDICATOR CURRENT NOT INCLUDED MAX8900A toc27 AVL VOLTAGE vs. INPUT VOLTAGE MAX8900A toc28 50 45 BATTERY LEAKAGE CURRENT (nA) 40 35 30 25 20 15 10 5 0 0 1 2 3 4 5 IN UNCONNECTED STAT INDICATOR CURRENT NOT INCLUDED 60 BATTERY LEAKAGE CURRENT (nA) 50 40 6 5 4 VAVL (V) 3 2 1 0 MAX8900x VOVLO = 28V VCEN = 0V VBAT = 3.6V RSETI = 2.87kI 0 5 10 15 VIN (V) 20 25 VOVLO 30 20 10 0 6 -40 -15 10 35 60 85 30 BATTERY VOLTAGE (V) TEMPERATURE (C) MAX8900_ CHARGE PROFILE (CONSTANT-CURRENT TO DONE MODES) 4.3 4.2 4.1 VOLTAGE (V) MAX8900A toc29 MAX8900_ CHARGE PROFILE (CHARGER RESTART) 1.4 1.2 BATTERY CURRENT (A) 4.3 4.2 4.1 VOLTAGE (V) 4.0 3.9 3.8 3.7 3.6 0 2000 4000 VIN = 5V RSETI = 4.02kI RDNI = 3.57kI CCT = 0.47F 1300mAh BATTERY IIN 6000 DONE CV MAX8900A toc30 1.4 1.2 BATTERY CURRENT (A) 1.0 0.8 0.6 CC CV VBAT DONE DONE 1.0 0.8 VBAT 4.0 3.9 3.8 3.7 3.6 500 2500 4500 VIN = 5V RSETI = 4.02kI RDNI = 3.57kI CCT = 0.47F 1300mAh BATTERY IIN 0.6 IBAT 0.4 0.2 0 10,500 IBAT 0.4 0.2 0 10,000 6500 8500 8000 TIME (s) TIME (s) 11 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B Typical Operating Characteristics (continued) (Circuit of Figure 1, VIN = 6V, VBAT = 3.6V, TA = +25NC, unless otherwise noted.) 5V IN CONNECT MAX8900A toc31 BATTERY CONNECT MAX8900A toc32 6V VIN 2V/div VIN 4.2V VBAT VLX 5V/div 1.2A 500mA/div RSETI = 2.87kI 20s/div 0A 2V/div 3.6V 5V/div IBAT RSETI = 6.81kI 400s/div 500mA/div 0A IBAT BATTERY DISCONNECT MAX8900A toc33 SOFT-START INTO RESISTIVE SOURCE, RSETI = 6.81kI VIN MAX8900A toc34 6V VIN 3.6V VBAT 1.2A IBAT RSETI = 2.87kI 400s/div 4.2V 2V/div 5V/div VSOURCE = 4.8V, VBAT = 4V 1I BETWEEN SOURCE AND IN 2V/div VLX 2V/div 500mA/div 0A IBAT 2ms/div 500mA/div 0A SOFT-START INTO RESISTIVE SOURCE (RSETI = 2.87kI) VIN MAX8900A toc35 5V/div VSOURCE = 4.8V, VBAT = 4V 1I BETWEEN SOURCE AND IN VLX 2V/div IBAT 2ms/div 500mA/div 0A 12 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring Pin Configuration TOP VIEW (BUMPS DOWN) + BAT A1 BAT B1 STAT2 C1 STAT1 D1 DNI E1 CS A2 CS B2 CEN C2 STAT3 D2 SETI E2 LX A3 LX B3 INBP C3 IN D3 CT E3 PGND A4 PGND B4 INBP C4 IN D4 THM E4 BST A5 PGND B5 INBP C5 IN D5 AVL E5 PVL A6 PGND B6 INBP C6 IN D6 GND E6 MAX8900A/MAX8900B 30 WLP (0.4mm PITCH) Pin Description PIN A1, B1 A2, B2 NAME BAT CS FUNCTION Connection to Battery. Connect to a single-cell Li+/Li-Poly battery from BAT to PGND. Connect both BAT pins together externally. Bypass BAT to PGND with a 2.2FF ceramic capacitor. 40mI Current-Sense Node. Connect the inductor from LX to CS. Connect both CS pins together externally. Inductor Switching Node. Connect the inductor between LX and CS. Connect both LX pins together externally. When enabled (CEN = 0), LX switches between INBP and PGND to control the battery charging. When disabled (CEN = 1), the LX switches are high-impedance however they still have body diodes as shown in Figure 3. Power Ground for Step-Down Low-Side Synchronous n-Channel MOSFET. Connect all PGND pins together externally. Supply for High-Side n-Channel Gate Driver. Bypass BST to LX with a 0.1FF ceramic capacitor. 5V Linear Regulator to Power Internal Circuits. PVL also charges the BST capacitor. Bypass PVL to PGND with a 1.0FF ceramic capacitor. Powering external loads from PVL is not recommended. Status Output 2. STAT2 is an open-drain output that has a 30V absolute maximum rating and a typical pulldown resistance of 25I. For the MAX8900A, STAT1 and STAT2 indicate different states as shown in Table 4. For the MAX8900B, STAT1, STAT2, and STAT3 indicate different operating states of the MAX8900_ as shown in Table 3. Charge Enable Input. CEN has an internal 200kI pulldown resistor. Pull CEN low or leave it unconnected to enable the MAX8900_. Drive CEN high to disable the MAX8900_. Note: VIN must be greater than VUVLO-RISING for the MAX8900_ to operate when CEN is pulled low. For example, if CEN is low and the MAX8900_ is operating with VUVLO-FALLING < VIN < VUVLO-RISING, then toggling CEN results in a nonoperating condition. A3, B3 A4, B4, B5, B6 A5 A6 LX PGND BST PVL C1 STAT2 C2 CEN 13 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B Pin Description (continued) PIN C3-C6 NAME INBP FUNCTION Power Input Bypass. Connect all INBP pins together externally. Bypass INBP to PGND with a 0.47FF ceramic capacitor. Status Output 1. STAT1 is an open-drain output that has a 30V absolute maximum rating and a typical internal pulldown resistance of 25I. For the MAX8900A, STAT1 and STAT2 indicate different states as shown in Table 4. For the MAX8900B, STAT1, STAT2, and STAT3 indicate different operating states of the MAX8900_ as shown in Table 3. Status Output 3. STAT3 is an open-drain output that is a 6V absolute maximum rating and a typical pulldown resistance of 10I. For the MAX8900A, STAT1 and STAT2 indicate different states as shown in Table 4. For the MAX8900B, STAT1, STAT2, and STAT3 indicate different operating states of the MAX8900_ as shown in Table 3. Power Input. IN is capable of delivering 1.2A to the battery and/or system. Connect all IN pins together externally. Bypass IN to PGND with a 0.47FF ceramic capacitor. Done/Prequalification Program Input. DNI is a dual function pin that sets both the done current threshold and the prequalification charge rate. Connect a resistor from DNI to GND to set the threshold between 10mA and 200mA. DNI is pulled to GND during shutdown. Fast-Charge Current Program Input. Connect a resistor from SETI to GND to set the fast-charge current from 0.05A to 1.2A. SETI is pulled to GND during shutdown. Charge Timer Set Input. A capacitor (CCT) from CT to GND sets the prequalification and fast-charge fault timers. Use 0.1FF for 180-minute fast-charge time limit and 30-minute prequalification time limit. Connect to GND to disable the timer. Thermistor Input. Connect a negative temperature coefficient (NTC) thermistor from THM to GND. Connect a resistor equal to the thermistor's +25NC resistance from THM to AVL. Thermistor adjusts the charge current and termination voltage as described in the JEITA specification for safe use of secondary Li+ batteries. See Figure 10. To disable the THM operation, bias VTHM midway between AVL and GND. 5V Linear Regulator to Power Low-Noise Internal Circuits. Bypass AVL to GND with a 0.1FF ceramic capacitor. Powering external loads from AVL is not recommended. Ground. GND is the low-noise ground connection for the internal circuitry. See the PCB Layout section for more details. D1 STAT1 D2 STAT3 D3-D6 E1 E2 E3 IN DNI SETI CT E4 THM E5 E6 AVL GND 14 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B 1FH 1.5A VIN RANGE: -22V TO +22V IN BAT 0.1FF 10V 0402 0.47FF 25V 0603 422I * * 422I BST LX IN CS BAT BAT PGND 2.2FF 6.3V 0603 Li+/ Li-POLY SYSTEM LOAD PGND GND 422I * MAX8900_ STAT1 STAT2 STAT3 ON CEN PVL INBP CT 0.47FF 6.3V 0402 AVL GND THM 0.1FF 6.3V 0201 10kI 0201 OFF 1.0FF 6.3V 0402 0.47FF 25V 0603 SETI 2.87kI 0201 DNI 3.57kI 0201 T 10kI 3380k 0402 THE MINIMUM ACCEPTABLE EIA COMPONENT SIZES AS OF LATE 2009 ARE LISTED: 0201, 0402, 0603. * STATUS INDICATORS ARE UNCONNECTED FOR THE ELECTRICAL CHARACTERISTICS TABLE. Figure 1. Applications Circuit: Single SETI Resistor, Status Indicators Connected to LEDs *PULLUP RESISTORS ARE INTERNAL TO THE P. USB CONNECTOR VBUS DD+ ID GND 0.1FF 10V 0402 0.47FF 25V 0603 0.47FF 25V 0603 INBP BST LX IN BAT PGND 2.2FF 6.3V 0603 Li+/ Li-POLY AVL GND THM T CT GPIO6 717mA_EN 0.47FF 6.3V 0402 PVL 1.0FF 6.3V 0402 DNI 3.57kI 0201 10kI 3380K 0402 PGND GND SYSTEM LOAD 1FH 1.5A GPIO4 CEN 1 0 0 0 0 GPIO5 GPIO6 RTH (I) IFC (A) 9090 4750 SUSPEND x x x 0 0 35700 0.095 1 0 7245 0.470 0 1 4192 0.812 1 1 2869 1.187 CS *SUSPEND IS 0mA FAST-CHARGE CURRENT (IFC) AND 40FA OF INPUT CURRENT (IIN). USB TRANSCEIVER GPIO1* GPIO2* GPIO3* GPIO4* 35.7kI 0201 375mA_EN 9.09kI 0201 STAT1 STAT2 STAT3 CEN SETI 4.75kI 0201 MAX8900_ 0.1FF 6.3V 0201 10kI 0201 FP GPIO5 THE MINIMUM ACCEPTABLE EIA COMPONENT SIZES AS OF LATE 2009 ARE LISTED: 0201, 0402, 0603. Figure 2. Applications Circuit: Multiple Charge Rates Managed by P to Be USB Compliant, Status Indicators Connected to a P 15 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B STAT1: D1 BV = 30V STAT2: C1 BV = 30V STAT3: D1 BV = 6V LOGIC BAT_T INPUT OVERVOLTAGE OVLO VOVLO GND: E6 CT: E3 CHARGER TIMER INPUT UNDERVOLTAGE UVLO VUVLO IN: D3 IN: D4 IN: D5 LOW IN TO BAT VOLTAGE IN: D6 CTS CEN: C2 RCEN PVL IN IN LI2B PVL: A6 RAVL 12.5I AVL: E5 AVL IS THE INTERNAL ANALOG SUPPLY OUT EN 5V 30mA LDO AVL IBAT BAT_I FC_I PQ_I TO_I BAT BAT_V REVERSEBATTERY PROTECTION VIN2BAT BAT PVL INBP: C3 INBP: C4 INBP: C5 INBP: C6 BST: A5 DC-DC CHARGE CONTROLLER SHDN SETI: E2 DNI: E1 AVL RHS DRV_OUT BAT_T BAT_T DIE_T PVL LX: A3 LX: B3 RLS PGND: A4 THERMOMETER DECODE LOGIC PGND: B4 DIE TEMPERATURE PGND: B5 PGND: B6 CS: A2 CS: B2 IBAT THM: E4 T COLD: T1 COOL: T2 PGND GND WARM: T3 IN OUT DEAD-BATTERY CHARGER (IDBAT) EN IN BAT RSNS BAT: A1 BAT: B1 HOT: T4 MAX8900A MAX8900B VDBAT Figure 3. Functional Diagram 16 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring Detailed Description The MAX8900_ is a full-featured, high-frequency switchmode charger for a 1-cell Li+ or Li-Poly battery. It delivers up to 1.2A to the battery from 3.4V to 6.3V (MAX8900A) or 3.4V to 8.7V (MAX8900B). Contact the factory for input operating voltage ranges up to +20V. The 3.25MHz switch-mode charger is ideally suited to small portable devices such as headsets and ultra-portable media players because it minimizes component size and heat. Several features make the MAX8900_ ideal for high reliability systems. The MAX8900_ is protected against input voltages as high as +22V and as low as -22V. Battery protection features include low voltage prequalification, charge fault timer, die temperature monitoring, and battery temperature monitoring. The battery temperature monitoring adjusts the charge current and termination voltage as described in the JEITA (Japan Electronics and Information Technology Industries Association) specification for safe use of secondary Li+ batteries. The full title of the standard is A Guide to the Safe Use of Secondary Lithium Ion Batteries in Notebook-Type Personal Computers, April 20, 2007. Charge parameters are easily adjustable with external components. An external resistance adjusts the charge current from 50mA to 1200mA. Another external resistance adjusts the prequalification and done current thresholds from 10mA to 200mA. The done current threshold is very accurate achieving Q1mA at the 10mA level. The charge timer is adjustable with an external capacitor. A proprietary hysteretic current PWM control scheme ensures high efficiency, fast switching, and physically tiny external components. Inductor ripple current is internally set to provide 3.25MHz. At very high duty factors, when the input voltage is lowered close to the output voltage, the steady-state duty ratio does not allow 3.25MHz operation because of the minimum off-time. The controller then provides minimum off-time, peak current regulation. Similarly, when the input voltage is too high to allow 3.25MHz operation due to the minimum on-time, the controller becomes a minimum on-time, valley current regulator. In this way, the ripple current in the inductor is always as small as possible to reduce the output ripple voltage. The inductor ripple current is made to vary with input and output voltage in a way that reduces frequency variation. To prevent input current transients, the rate of change of the input current (di/dt) and charge current is limited. When the input is valid, the charge current ramps from 0mA to the fast-charge current value in 1.5ms. Charge current also soft-starts when transitioning from the prequalification state to the fast-charge state. There is no di/dt limiting when transitioning from the done state to the fast-charge state (Figures 7 and 8). Similarly, if RSETI is changed suddenly when using a switch or variable resistor at SETI as shown in Figure 2 there is no di/ dt current limiting. As shown in Figure 4, a resistor from SETI to ground (RSETI) sets the fast-charge current (IFC). The MAX8900_ supports values of IFC from 50mA to 1200mA. Select RSETI as follows: IFC = 3405V/RSETI Determine the optimal IFC for a given system by considering the characteristics of the battery and the capabilities of the charge source. Example 1: If you are using a 5V Q5% 1A charge source along with an 800mAh battery that has a 1C fast-charge rating, then choose RSETI to be 4.42kI Q1%. This value provides a typical charge current of 770mA. Given the Q2% six sigma limit on the MAX8900_ fast-charge current accuracy along with the Q1% accuracy of the resistor, we can reasonably expect that the 770mA typical value has an accuracy of Q2.2% (2.2 sqrt(22 + 12)) or Q17mA. Furthermore, since the MAX8900_ charger uses a step-down converter topology, we can guarantee that the input current is less than or equal to the output current so we do not violate the 1A rating of the charge source. Depending on its mode of operation, the MAX8900_ controls the voltage at SETI to be between 0V and 1.5V. Avoid adding capacitance directly to the SETI pin that exceeds 10pF. As a protection feature, if the battery temperature is between the T2 and T4 thresholds and SETI is shorted to ground, then the MAX8900_ latches off the battery charger and enters the timer fault state. This protection feature is disabled outside of fast-charge, top-off, done mode and inside thermal foldback. Furthermore, if SETI is unconnected, then the battery fast-charge current is 0A. Soft-Start MAX8900A/MAX8900B Setting the Fast-Charge Current (SETI) Control Scheme 17 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B As shown in Figure 5, a resistor from DNI to ground (RDNI) sets the prequalification current (IPQ) and done current (IDN). The MAX8900_ supports values of RDNI from 1.19kI to 38.2kI. Select RDNI as follows: IDN = 384V/RDNI IPQ = 415V/RDNI Setting the Prequalification Current and Done Threshold (DNI) Depending on its mode of operation, the MAX8900_ controls the voltage at DNI from 0 to 1.5V. Avoid adding capacitance directly to the SETI pin that exceeds 10pF. As shown in Figure 10, the prequalification current and done threshold is set to 50% of programmed value when T1 < THM < T2, and 100% of programmed value when T2 < THM < T4. As a protection feature, if the battery temperature is between the T2 and T4 thresholds and DNI is shorted to ground, then the MAX8900_ latches off the battery charger and enters the timer fault state. This protection feature is disabled inside of dead-battery mode and thermal foldback. Furthermore, if DNI is unconnected, then the prequalification and done current is 0A and the charge timer prevents the MAX8900_ from indefinitely operating in its done state. CEN is a digital input. Driving CEN high disables the battery charger. Pull CEN low or leave it unconnected PREQUALIFICATION AND DONE CURRENT vs. RDNI 250 Determine the optimal IPQ and IDN for a given system by considering the characteristics of the battery. FAST-CHARGE CURRENT vs. RSETI 1.4 1.2 FAST-CHARGE CURRENT (A) 1.0 0.8 0.6 0.4 0.2 0 0 20 40 RSETI (kI) 60 80 Charge Enable Input (CEN) 200 RSETI (kI) 2.87 3.01 3.16 3.32 3.57 3.92 4.12 4.32 4.42 4.75 4.99 5.11 5.62 6.19 6.81 7.5 IFC (A) 1.186 1.131 1.078 1.026 0.954 0.869 0.826 0.788 0.770 0.717 0.682 0.666 0.606 0.550 0.500 0.454 RSETI (kI) 7.15 7.32 7.87 8.25 9.09 10.0 11.0 12.1 13.0 14.0 15.0 16.2 18.2 20.0 22.1 24.3 IFC (A) 0.476 0.465 0.433 0.413 0.375 0.341 0.310 0.281 0.262 0.243 0.227 0.210 0.187 0.170 0.154 0.140 RSETI (kI) 24.9 27.4 30.1 32.2 34.0 35.7 39.2 43.2 45.5 49.9 51.1 56.2 61.9 66.5 68.1 IFC (A) 0.137 0.124 0.113 0.106 0.100 0.095 0.087 0.079 0.075 0.068 0.067 0.061 0.055 0.051 0.050 CURRENT (mA) 150 IPQ 100 IDN 50 0 0 10 RDNI (kI) 100 RDNI (kI) 1.91 2.37 3.48 3.57 3.83 4.42 5.9 7.32 IPQ (mA) 217.3 175.1 119.3 116.2 108.4 93.9 70.3 56.7 IDN (mA) 201.0 162.0 110.3 107.6 100.3 86.9 65.1 52.5 RDNI (kI) 7.5 7.68 7.87 10.0 14.3 20.0 28.0 39.2 IPQ (mA) 55.3 54.0 52.7 41.5 29.0 20.8 14.8 10.6 IDN (mA) 51.2 50.0 48.8 38.4 26.9 19.2 13.7 9.8 Figure 4. Fast-Charge Current vs. RSETI (www.maxim-ic.com/ tools/other/software/MAX8900-RSETI.XLS) 18 Figure 5. Prequalification Current and Done Threshold vs. RDNI (www.maxim-ic.com/tools/other/software/MAX8900-DNI.XLS) 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring to enable the MAX8900_. CEN has an internal 200kI pulldown resistor. When disabled, the MAX8900_ supply current is reduced, the step-down converter high-side and low-side switches are off, and the AVL is disabled. In many systems, there is no need for the system controller (typically a microprocessor (FP)) to disable the charger because the MAX8900_ independently manages the charger. In these situations, CEN can be connected to ground or left unconnected. Note: if CEN is permanently connected to ground or left unconnected, the input power must be cycled to escape from a timer fault state (see Figures 7 and 8 for more information). VIN must be greater than VUVLO-RISING for the MAX8900_ to operate when CEN is pulled low. For example, if CEN is low and the MAX8900_ is operating with VUVLO-FALLING < VIN < VUVLO-RISING, then toggling CEN results in a nonoperating condition. The MAX8900_ utilizes several charging states to safely and quickly charge batteries as shown in Figure 7. Figure 6 shows an exaggerated view of a Li+/Li-Poly battery progressing through the following charge states when the die and battery are close to room temperature: dead battery e prequalification e fast-charge e top-off e done. FAST-CHARGE (CONSTANT CURRENT) FAST-CHARGE (CONSTANT VOLTAGE) MAX8900A/MAX8900B Charger States DEAD BATTERY + PREQUALIFICATION PREQUALIFICATION DEAD BATTERY TOP-OFF VBATREG BATTERY VOLTAGE VPQUTH VDBAT VPQLTH TIME ICHG P ISET BATTERY CHARGE CURRENT IDBAT + IPQ IPQ IDBAT 0 TIME Figure 6. Li+/Li-Poly Charge Profile 19 DONE 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B NO PWR OR CHARGER DISABLED STAT1 = HI-Z STAT2 = HI-Z STAT3 = HI-Z IBAT = 0 VIN > VUVLO AND VIN > VBAT + VIN2BAT AND TJ < TSHDN DEAD BAT STAT1 = LOW STAT2 = HI-Z STAT3 = LOW IBAT = IDBAT VBAT < VPQLTH VBAT > VPQLTH (SET TIMER = 0) CEN = LOGIC-HIGH OR TJ > TSHDN VIN < VUVLO OR < VBAT + VIN2BAT ANY STATE VIN TOO HIGH STAT1 = LOW STAT2 = LOW STAT3 = HI-Z IBAT = 0 VIN < VOVLO TIMER = RESUME VIN > VOVLO TIMER = SUSPEND DEAD BAT + PREQUAL STAT1 = LOW STAT2 = HI-Z STAT3 = LOW IBAT = IDBAT + IPQ VBAT < VDBAT PREQUAL STAT1 = LOW STAT2 = HI-Z STAT3 = LOW IBAT = IPQ VBAT < VPQUTH (SET TIMER = 0) FAST CHG STAT1 = LOW STAT2 = HI-Z STAT3 = LOW IBAT = IFC IBAT > IDN + 1mA (SET TIMER = 0) IBAT < IDN VBAT > VPQUTH SOFT-START (SET TIMER = 0) TIMER > tPQ VBAT > VDBAT TIMER > tPQ ANY CHARGING STATE (DEAD BAT, PREQUAL, FAST CHG, OR TOP-OFF) TIMER FAULT STAT1 = HI-Z STAT2 = HI-Z STAT3 = LOW IBAT = 0 THERMISTOR < T1 TIMER = SUSPEND THERMISTOR > T1 TIMER = RESUME BATTERY COLD STAT1 = LOW STAT2 = LOW STAT3 = LOW IBAT = 0 IF VBAT > VDBAT TIMER > tFC THERMISTOR > T4 TIMER = SUSPEND THERMISTOR < T4 TIMER = RESUME TOP-OFF BATTERY HOT STAT1 = LOW STAT2 = HI-Z STAT3 = HI-Z IBAT = 0 IF VBAT > VDBAT STAT1 = LOW STAT2 = HI-Z STAT3 = LOW TIMER > tTO DONE STAT1 = HI-Z STAT2 = LOW STAT3 = LOW IBAT = 0 VBAT < VRSTRT NO SOFT-START (SET TIMER = 0) Figure 7. Charger State Diagram (3-Pin Status) 20 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B NO PWR OR CHARGER DISABLED STAT1 = HI-Z STAT2 = HI-Z IBAT = 0 VIN > VUVLO AND VIN > VBAT + VIN2BAT AND TJ < TSHDN DEAD BAT STAT1 = LOW STAT2 = HI-Z IBAT = IDBAT VBAT < VPQLTH VBAT > VPQLTH (SET TIMER = 0) DEAD BAT + PREQUAL STAT1 = LOW STAT2 = HI-Z IBAT = IDBAT + IPQ VBAT < VDBAT PREQUAL STAT1 = LOW STAT2 = HI-Z IBAT = IPQ VBAT < VPQUTH (SET TIMER = 0) FAST CHG STAT1 = LOW STAT2 = HI-Z IBAT = IFC IBAT > IDN + 1mA (SET TIMER = 0) TOP-OFF STAT1 = LOW STAT2 = HI-Z IBAT < IDN TIMER > tFC VBAT > VPQUTH SOFT-START (SET TIMER = 0) TIMER > tPQ VBAT > VDBAT TIMER > tPQ CEN = LOGIC-HIGH OR TJ > TSHDN VIN < VUVLO OR < VBAT + VIN2BAT ANY STATE VIN TOO HIGH STAT1 = HI-Z STAT2 = LOW IBAT = 0 VIN < VOVLO TIMER = RESUME VIN > VOVLO TIMER = SUSPEND ANY CHARGING STATE (DEAD BAT, PREQUAL, FAST CHG, OR TOP-OFF) TIMER FAULT STAT1 = HI-Z STAT2 = LOW IBAT = 0 THERMISTOR > T4 OR THERMISTOR < T1 TIMER = SUSPEND T1 < THERMISTOR < T4 TIMER = RESUME BATTERY COLD/ BATTERY HOT STAT1 = HI-Z STAT2 = LOW IBAT = 0 IF VBAT > VDBAT VBAT < VRSTRT NO SOFT-START (SET TIMER = 0) TIMER > tTO DONE STAT1 = HI-Z STAT2 = HI-Z IBAT = 0 Figure 8. Charger State Diagram (2-Pin Status) 21 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B Charger Disabled State When CEN is high or the input voltage is out of range, the MAX8900_ disables the charger. To exit this state, CEN must be low and the input voltage must be within its valid range. Dead-Battery State When a deeply discharged battery is inserted with a voltage of less than VPQLTH, the MAX8900_ disables the switching charger and linearly charges with IDBAT. Once VBAT increases beyond VPQLTH, the MAX8900_ clears the prequalification timer and transitions to the dead battery + prequalification state. This state prevents the MAX8900_ from dissipating excessive power in the event of a shorted battery. The dead-battery linear charger remains on except when in the charger disabled state, timer fault state, thermal shutdown, and VBAT > VDBAT. Dead Battery + Prequalification State The dead battery + prequalification state occur when the battery voltage is greater than VPQLTH and less than VDBAT. In this state, both the linear dead-battery charger and the switching charger are on and delivering current to the battery. The total battery current is IDBAT + IPQ. If the MAX8900_ remains in this state for longer than tPQ, then the MAX8900_ transitions to the timer fault state. A normal battery typically stays in this state for several minutes or less and when the battery voltage rises above VDBAT, the MAX8900_ transitions to the prequalification state. The dead-battery linear charger remains on except when in the charger disabled state, timer fault state, thermal shutdown, and VBAT > VDBAT. Prequalification State The prequalification state occurs when the battery voltage is greater than VDBAT and less than VPQUTH. In this state, the linear dead-battery charger is turned off and only the switching charger is on and delivering current to the battery. The total battery current is IPQ. If the MAX8900_ remains in this state for longer than tPQ, then the MAX8900_ transitions to the timer fault state. A normal battery typically stays in the prequalification state for several minutes or less and when the battery voltage rises above VPQUTH, the MAX8900_ transitions to the fast-charge constant current state. As shown in Figure 10, the prequalification current and done threshold is set to 50% of programmed value when T1 < THM < T2, and 100% of programmed value when T2 < THM < T4. Fast-Charge Constant Current State The fast-charge constant current state occurs when the battery voltage is greater than VPQUTH and less than 22 VBATREG. In this state, the switching charger is on and delivering current to the battery. The total battery current is IFC. If the MAX8900_ remains in this state and the fastcharge constant voltage state for longer than tFC, then the MAX8900_ transitions to the timer fault state. When the battery voltage rises to VBATREG, the MAX8900_ transitions to the fast-charge constant voltage state. As shown in Figure 10, the fast-charge constant current is set to 50% of programmed value when T1 < THM < T2, and 100% of programmed value when T2 < THM < T4. The MAX8900_ dissipates the most power in the fastcharge constant current state. This power dissipation causes the internal die temperature to rise. If the die temperature exceeds TREG, IFC is reduced. See the Thermal Foldback section for more detail. If there is low input voltage headroom (VIN - VBAT), then IFC decreases due to the impedance from IN to BAT. See Figure 13 for more detail. Fast-Charge Constant Voltage State The fast-charge constant voltage state occurs when the battery voltage is at the VBATREG and the charge current is greater than IDN. In this state, the switching charger is on and delivering current to the battery. The MAX8900_ maintains VBATREG and monitors the charge current to detect when the battery consumes less than the IDN current. When the charge current decreases below the IDN threshold, the MAX8900_ transitions to the top-off state. If the MAX8900_ remains in the fast-charge constant current state and this state for longer than tFC, then the MAX8900_ transitions to the timer fault state. Please note when the battery temperature is between T3 and T4 the BAT regulation voltage is reduced to 4.075V. The MAX8900_ offers an adjustable done current threshold (IDN) from 10mA to 200mA. The accuracy of the top-off current threshold is Q1mA when it is set for 10mA. This accurate threshold allows the maximum amount of charge to be stored in the battery before the MAX8900_ transitions into done state. Top-Off State The top-off state occurs when the battery voltage is at VBATREG and the battery current decreases below IDN. In this state, the switching charger is on and delivers current to the battery. The MAX8900_ maintains VBATREG for a specified time (tTO). When tTO expires, the MAX8900_ transitions to the done state. If the charging current increases to IDN + 1mA before tTO expires, then the charger re-enters the fast-charge constant voltage state. 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring Done State The MAX8900_ enters its done state after the charger has been in the top-off state for tTO. In this state, the switching charger is off and no current is delivered to the battery. Although the charger is off, the SETI and DNI pins are biased in the done state and the MAX8900_ consumes the associated current from the battery (IBAT = 1.5V/RSETI + 1.5V/RDNI + 3FA). If the system load presented to the battery is low (<< 100FA), then a typical system can remain in the done state for many days. If left in the done state long enough, the battery voltage decays below the restart threshold (VRSTRT) and the MAX8900_ transitions back into the fast-charge state. There is no soft-start (di/dt limiting) during the done-tofast-charge state transition. Timer Fault State The timer fault state occurs when either the prequalification or fast-charge timers expire, or SETI/DNI is shorted to ground. See the Setting the Fast-Charge Current (SETI) and Setting the Prequalification Current and Done Threshold (DNI) sections for more details. In this state the charger is off. The charger can exit the timer fault state by either cycling CEN or input power. Battery Hot/Cold State The battery hot/cold state occurs when the MAX8900_ is in any of its charge states (dead battery, prequalification, fast-charge, top-off) and thermistor temperature is either less than T1 or greater than T4. In this state, the charger is off and timers are suspended. The MAX8900_ exits the temperature suspend state and returns to the state it came from once the thermistor temperature is greater than T1 and less than T4. The timer resumes once the MAX8900_ exits this state. VIN Too High State The VIN too high state occurs when the MAX8900_ is in any of its charge states (dead battery, prequalification, fast-charge, top-off) and VIN exceeds VOVLO. In this state, the charger is off and timers are suspended. The MAX8900_ exits the VIN too high state and returns to the state it came from when VIN decreases below VOVLO. The timer resumes once the MAX8900_ exits this state. As shown in Figure 7, a fault timer prevents the battery from charging indefinitely. In prequalification and fastcharge states, the timer is controlled by the capacitance at CT (CCT). The MAX8900_ supports values of CCT from 0.01FF to 1.0FF. Calculate the prequalification time (tPQ) and fast-charge time (tFC) as follows (Figure 9): MAX8900A/MAX8900B CHARGE TIMES vs. CHARGE TIMER CAPACITOR 2000 1800 1600 CHARGE TIMES (min) 1400 1200 1000 800 600 400 200 0 0 200 400 600 800 1000 CCT (nF) tPQ tFC CCT (nF) 68 100 150 220 470 1000 tPQ (min) 20.4 30.0 45.0 66.0 141.0 300.0 tFC (min) 122.4 180.0 270.0 396.0 846.0 1800.0 (hrs) 2 3 4.5 6.6 14.1 30.0 tTO (s) 16 16 16 16 16 16 Figure 9. Charge Times vs. CCT t PQ = 30min x t FC = 180min x C CT 0.1FF C CT 0.1FF The top-off time (tTO) is fixed at 16s: t TO = 16s Connect CT to GND to disable the prequalification and fast-charge timers. With the internal timers of the MAX8900_ disabled, an external device, such as a FP can control the charge time through the CEN input. The MAX8900_ is packaged in a 2.44mm x 2.67mm x 0.64mm, 0.4mm pitch WLP package and withstands a junction temperature of +150NC. The MAX8900_ is rated for the extended ambient temperature range from -40NC to +85NC. Table 1 and Application Note 1891: Wafer-Level Packaging (WLP) and Its Applications (www.maxim-ic.com/ucsp) show the thermal characteristics of this package. The MAX8900_ uses several Thermal Management Charge Timer (CT) 23 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B Table 1. 2.44mm x 2.67mm x 0.64mm, 0.4mm Pitch WLP Thermal Characteristics FOUR-LAYER PCB (JESD51-9:2s2p) Continuous Power Dissipation BJA BJC 1619mW Derate 20.2mW/NC above +70NC/W 49.4NC/W 9NC/W * * * * * * * * Still air 4-layer board 1.5oz copper on outer layers 1oz copper on inner layers 1.6mm thick board (62mil) 4in x 4in board Four center thermal vias FR-4 If the thermistor functionality is not required, connect a 1MI resistor from THM to AVL and another 1MI resistor from THM to GND. This biases the THM node to be 1/2 of the AVL voltage telling the MAX8900_ that the battery temperature is between the T2 and T3 temperature range. Furthermore, the high 2MI impedance presents a minimal load to AVL. Table 2 shows that the MAX8900_ is compatible with several standard thermistor values. When using a 10kI thermistor with a beta of 3380K, the configuration of Figure 11A provides for temperature trip thresholds that are very close to the nominal T1, T2, T3, and T4 (see the Electrical Characteristics table). When using alternate resistance and/or beta thermistors, the circuit of Figure 11A may result in temperature trip thresholds that are different from the nominal values. In this case, the circuit of Figure 11B allows for compensating the thermistor to shift the temperature trip thresholds back to the nominal value. In general, smaller values of RTP shift all the temperature trip thresholds down; however, the lower temperature thresholds are affected more then the higher temperature thresholds. Furthermore, larger values of RTS shift all the temperature trip thresholds up; however, the higher temperature thresholds are affected more than the lower temperature thresholds. For assistance with thermistor calculations, use the spreadsheet at the following link: www.maxim-ic.com/tools/other/software/MAX8900THERMISTOR.XLS The general relation of thermistor resistance to temperature is defined by the following equation: 1 1 T +273NC 298NC xe Board Parameters thermal management techniques to prevent excessive battery and die temperatures. Thermistor Monitor (THM) The MAX8900_ adjusts the charge current and termination voltage as described in the JEITA specification for safe use of secondary Li+ batteries (A Guide to the Safe Use of Secondary Lithium Ion Batteries in Notebook-type Personal Computers, April 20, 2007). As shown in Figure 10, there are four temperature thresholds that change the battery charger operation: T1, T2, T3, and T4. When the thermistor input exceeds the extreme temperatures (< T1 or > T4), the charger shuts off and all respective charging timers are suspended. While the thermistor remains out of range, no charging occurs, and the timer counters hold their state. When the thermistor input comes back into range, the charge timers continue to count. The middle thresholds (T2 and T3) do not shut the charger off, but adjust the current/voltage targets to maximize charging while reducing battery stress. Between T3 and T4, the voltage target is reduced (see VBATREG in the Electrical Characteristics table); however, the charge timers continue to count. Between T1 and T2, the charging current target is reduced to 50% of its normal operating value; and similarly the charge timers continue to count. R THRM = R 25 where: RTHRM = The resistance in I of the thermistor at temperature T in Celsius. R25 = The resistance in I of the thermistor at TA = +25NC. = The material constant of the thermistor, which typically ranges from 3000K to 5000K. T = The temperature of the thermistor in NC. 24 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring Table 2. Trip Temperatures for Different Thermistors THERMISTOR RTHRM at TA = +25NC Thermistor Beta ([I]) RTB (I) RTP (I) RTS (I) Resistance at T1_n15 (I) Resistance at T1_0 (I) Resistance at T2 (I) Resistance at T3 (I) Resistance at T4 (I) Temperature at T1_n15 (NC) [-15NC nom] Temperature at T1_0 (NC) [0NC nom] Temperature at T2 (NC) [+15NC nom] Temperature at T3 (NC) [+45NC nom] Temperature at T4 (NC) [+60NC nom] 10,000 3380 10,000 OPEN SHORT 61,788 29,308 15,000 5,309 2,910 -16.2 -0.8 14.7 42.6 61.4 10,000 3940 10,000 OPEN SHORT 61,788 29,308 15,000 5,309 2,910 -11.1 2.6 16.1 40.0 55.7 10,000 3940 10,000 301,000 499 77,248 31,971 15,288 4,906 2,439 -14.9 0.9 15.7 42.0 60.6 TEMPERATURE 47,000 4050 47,000 OPEN SHORT 290,410 137,750 70,500 24,954 13,676 -10.2 3.2 16.4 39.6 54.8 47,000 4050 47,000 1,200,000 2,400 380,716 153,211 72,500 23,083 11,434 -14.8 1.2 15.8 41.5 59.6 100,000 4250 100,000 OPEN SHORT 617,913 293,090 150,002 53,093 29,099 -8.7 4.1 16.8 38.8 53.2 100,000 4250 100,000 1,800,000 6,800 934,027 343,283 156,836 47,906 22,777 -15.4 1.3 15.9 41.2 59.2 MAX8900A/MAX8900B BAT REGULATION VOLTAGE (V) 4.2 4.2V *CONTACT FACTORY FOR A 4.1V OPTION FOR VBATREG. 4.1 4.1V* 4.075V 4.0 -40 T1 15 T2 25 45 T3 60 T4 85 BATTERY TEMPERATURE (C) IFC = 3405V RSETI T1 = 0C for MAX8900A T1 = -15C for MAX8900B CHARGE CURRENT (A) 3405V IFC = 2 x RSETI IPQ = 415V RDNI IPQ = 415V 2 x RDNI IDBAT -40 T1 15 T2 25 45 T3 60 T4 85 BATTERY TEMPERATURE (C) Figure 10. JEITA Battery Safety Regions 25 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B A. BASIC THERMISTOR CONFIGURATION AVL: E5 RTB THM: E4 RTHRM T RTP RTS AVL B. ADVANCED THERMISTOR CONFIGURATION AVL: E5 AVL IS THE INTERNAL ANALOG SUPPLY AVL MAX8900_ RTB THM: E4 AVL IS THE INTERNAL ANALOG SUPPLY MAX8900_ COLD: T1 COLD: T1 THERMOMETER DECODE LOGIC COOL: T2 T BAT_T RTHRM THERMOMETER DECODE LOGIC COOL: T2 BAT_T TO DC-DC CHARGE CONTROLLER TO DC-DC CHARGE CONTROLLER WARM: T3 WARM: T3 HOT: T4 HOT: T4 Figure 11. Thermistor Monitor Detail Thermal Foldback Thermal foldback maximizes the battery charge current while regulating the MAX8900_ junction temperature. As shown in Figure 12, when the die temperature exceeds TREG, a thermal limiting circuit reduces the battery charge-current target by ATREG, until the charge current reaches 25% of the fast-charge current setting. The charger maintains 25% of the fast-charge current until the die temperature reaches TSHDN. Please note that the MAX8900_ is rated for a maximum ambient temperature of +85NC. Furthermore, although the maximum die temperature of the MAX8900_ is +150NC, it is common industry practice to design systems in such a way that the die temperature never exceeds +125NC. Limiting the maximum die temperature to +125NC extends long-term reliability. Thermal Shutdown As shown in Figure 12, when the MAX8900_ die temperature exceeds TSHDN, the IC goes into thermal shutdown. During shutdown, the step-down charger is off and all internal blocks except the bias circuitry is turned off. Once the junction has cooled by 15NC, the IC resumes operation. CHARGE CURRENT vs. JUNCTION TEMPERATURE 1.4 1.2 1.0 ICHG (A) 0.8 0.6 0.4 0.2 0 50 75 100 125 150 175 TJ (C) IFC = 0.756A IFC = 1.19A T2 < VTHM < T3 Figure 12. Charge Current vs. Junction Temperature 26 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring PVL is a 5V linear regulator that the MAX8900_ uses to power the gate drivers for its step-down charger. PVL also charges the BST capacitor. The PVL linear regulator is on when CEN is low, VIN is greater than ~2V, and VIN is above VBAT by the VIN2BAT threshold, otherwise it is off. Bypass PVL with a 1FF ceramic capacitor to GND. Powering external loads from PVL is not recommended. As shown in Figure 3, AVL is a filtered output from the PVL linear regulator that the MAX8900_ uses to power its internal analog circuits. The filter consists of an internal 12.5I resistor and the AVL external bypass capacitor (0.1FF). This filter creates a 127kHz lowpass filter that cleans the 3.25MHz switching noise from the analog portions of the MAX8900_. Connect a 0.1FF ceramic capacitor from AVL to GND. Powering external loads with AVL is not recommended. STAT1, STAT2, and STAT3 are open-drain outputs that indicate the status of the MAX8900B as shown in Table 3. PVL and AVL Regulator than 30mA (Figure 1). The STAT1 and STAT2 typical pulldown resistance is 25I and the absolute maximum rating is +30V. This +30V rating allows IN to be used to bias STAT1 and STAT2. The STAT3 typical pulldown resistance is 10I and the absolute maximum rating is +6V. STAT1 and STAT2 are open-drain outputs that indicate the status of the MAX8900A as shown in Table 4. When the status outputs are used to communicate with a FP, pull them up to the system logic voltage (VLOGIC) to create a signal that has a logic-high and logic-low state that the FP can easily interpret (Figure 2). Since more than one status signal may change when the MAX8900A changes states, the FP must implement a deglitching routine for the interpretation of the status signals. When the status outputs are used to drive LED indicators, a series resistor should limit the LED current to be less than 30mA (Figure 1). Note that the STAT1 and STAT2 typical pulldown resistance is 25I and the absolute maximum rating is +30V. This +30V rating allows IN to be used to bias STAT1 and STAT2. STAT3 pulls low when the battery temperature monitor detects that the battery temperature is greater than the T4 threshold, otherwise, STAT3 is high impedance. Some systems may want to reduce the battery loading when STAT3 pulls low to prevent the battery from getting excessively hot. MAX8900A/MAX8900B Charge Status Outputs (2 Pin + > T4) Charge Status Outputs (3 Pin) When the status outputs are used to communicate with a FP, pull them up to the system logic voltage (VLOGIC) to create a signal that has a logic-high and logic-low state that the FP can easily interpret (Figure 2). Since more than one status signal may change when the MAX8900B changes states, the FP must implement a deglitching routine for the interpretation of the status signals. When the status outputs are used to drive LED indicators, a series resistor should limit the LED current to be less Table 3. 3-Pin Status Output Truth Table STAT1 0 0 0 0 1 1 1 1 STAT2 0 0 1 1 0 0 1 1 STAT3 0 1 0 1 0 1 0 1 INDICATION Battery cold (THM < T1) VIN > VOVLO Charging (dead-battery state or dead battery + prequalification state or prequalification state or fast-charge state) Battery hot (THM >T4) Done state Undefined Timer fault VIN < VUVLO or CEN = 1 or VIN < (VBAT + VIN2BAT) or thermal shutdown 1 1 1 0 Table 4. 2-Pin Status Output Truth Table STAT1 0 0 STAT2 0 1 INDICATION Undefined Charging (dead-battery state or dead battery + prequalification state or prequalification state or fastcharge state) Timer fault or VIN > VOVLO or battery cold (THM < T1) or battery hot (THM > T4) Done state or CEN = 1 or VIN < VUVLO or VIN < (VBAT + VIN2BAT) or thermal shutdown Note: STAT1, STAT2, and STAT3 are open-drain outputs. "0" indicates that the output device is pulling low. "1" indicates that the output is high impedance. Note: STAT1 and STAT2 are open-drain outputs. "0" indicates that the output device is pulling low. "1" indicates that the output is high impedance. 27 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B Consider inductance, current rating, series resistance, physical size, and cost when selecting an inductor. These factors affect the converter's efficiency, maximum output current, transient response time, and output voltage ripple. Tables 5 and 6 show suggested inductor values based upon input voltage and laboratory tests. Inductor Selection to 10FH. Higher input voltages require higher inductors to maintain the same inductor current ripple. The trade-off between inductor size and converter efficiency for step-down regulators varies as the LIR varies. LIR is the ratio of the inductor peak-to-peak ripple current to the average DC inductor current at the full-load current. A higher LIR value allows for smaller inductance, but result in higher losses and higher output voltage ripple. To reduce the power dissipation and improve transient response, choose an inductor that has a low DC series resistance as well as a low AC resistance at 3.25MHz. Note that it is typical for low inductance inductors such as 1FH to have a Q30% initial variation in inductance. Furthermore, some physically smaller inductors show a substantial degradation in inductance with increased DC current. It is typical for inductor manufacturers to specify their saturation current at the level when the initial inductance decreases by 30% or at the level where the internal inductor temperature rises +40NC above the ambient temperature. Because of differences in the way inductor manufacturers specify saturation current (ISAT), it is critical that you study and understand your manufacturer's specification criteria. When using the MAX8900_ with IN voltages below 8.5V, select the inductor to be 1.0FH. This keeps the inductor peak-to-peak ripple current to the average DC inductor current at the full load (LIR) between 40% to 50%. If a lower ripple is desired, select an inductance from 2.2FH Table 5. Recommended Inductor Selection DC INPUT VOLTAGE RANGE (V) 3.4 to 8.7 8.7 to 15.8 15.8 to 27.4 RECOMMENDED INDUCTOR FOR 40% LIR 1FH inductor, LQM2HPN1R0G0, Murata, 2.5mm x 2.0mm x 0.9mm, 55mI, 1.6A. 1.5FH inductor, LQM2HPN1R5G0, Murata, 2.5mm x 2.0mm x 0.9mm, 70mI, 1.5A 2.2FH inductor, LQM2HPN2R2G0, Murata, 2.5mm x 2.0mm x 0.9mm, 80mI, 1.3A. Table 6. Recommended Inductor MANUFACTURER Coilcraft SERIES EPL2014 INDUCTANCE (H) 1.0 1.5 2.2 1.0 1.5 2.2 3.3 1.0 1.5 2.2 3.3 1.0 1.5 1.0 2.2 1.0 1.5 2.2 1.0 1.5 2.2 3.3 ESR (I) 0.059 0.075 0.120 0.085 0.110 0.110 0.120 0.055 0.070 0.080 0.100 0.060 0.070 0.090 0.135 0.110 0.140 0.16 0.085 0.095 0.105 0.115 CURRENT RATINGS (A) 1.68 1.60 1.30 1.40 1.20 1.20 1.20 1.60 1.50 1.30 1.20 1.50 1.50 1.20 0.90 1.20 1.10 1.05 1.35 1.25 1.20 1.15 DIMENSIONS 2.0 x 2.0 x 1.4 = 5.6mm3 LQM2MPN_G0 Murata LQM2HPN_G0 2.0 x 1.6 x 0.9 = 2.88mm3 2.5 x 2.0 x 0.9 =4.5mm3 MLP2520S TDK CPL2512 MDT2520-CH TOKO MDT2520-CN 2.0 x 2.5 x 1.0 = 5mm3 2.5 x 1.5 x 1.2 = 3.6mm3 2.5 x 2.0 x 1.0 = 5mm3 2.5 x 2.0 x 1.2 = 6mm3 28 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring If the input voltage approaches the BAT voltage during fast-charge constant current state, the maximum current is no longer limited by the current loop, but by the dropout resistance. The total dropout resistance is: RDROPOUT = RIN2INBP + RHS + RL + RSNS = 0.120I + 0.100I + RL + 0.040I RDROPOUT heavily depends upon the inductor ESR (RL). A low RL is required to maximize performance. Choose the nominal BAT capacitance to be 2.2FF. The BAT capacitor is required to keep the BAT voltage ripple small and to ensure regulation loop stability. The BAT capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R dielectric are highly recommended due to their small size, low ESR, and small temperature coefficients. For optimum loadtransient performance and very low output voltage ripple, the BAT capacitor value can be increased above 2.2FF. As the case sizes of ceramic surface-mount capacitors decreases, their capacitance vs. DC bias voltage characteristic becomes poor. Due to this characteristic, it is possible for 0603 capacitors to perform well while 0402 capacitors of the same value perform poorly. The MAX8900_ require a nominal BAT capacitance of 2.2FF, however, after initial tolerance, bias voltage, aging, and temperature derating, the capacitance must be greater than 1.5FF. With the capacitor technology that is available at the time the MAX8900_ was released to production, the BAT capacitance is best achieved with a single ceramic capacitor (X5R or X7R) in an 0603 or 0805 case size. The capacitor voltage ratings should be 6.3V or greater. CALCULATED FAST-CHARGE CURRENT vs. DROPOUT VOLTAGE 1.4 1.2 FAST-CHARGE CURRENT (A) 1.0 0.8 0.6 0.4 0.2 0 0 0.2 0.4 0.6 0.8 1.0 VIN - VBAT (V) RL = 300mI IFC = 500mA RL = 40mI IFC = 1200mA BAT Capacitor Choose the INBP capacitance (CINBP) to be 0.47FF. Larger values of CINBP improve the decoupling for the DC-DC step-down converter, but they cause a larger IN to INBP inrush current when the input adapter is connected. To limit the IN inrush current (IIN) to the 2.4A maximum (see the Absolute Maximum Ratings section), limit CINBP by the maximum input voltage slew rate (VINSR) on IN: CINBP < 2.4A/VINSR. CINBP reduces the current peaks drawn from the battery or input power source during switch-mode operation and reduces switching noise in the MAX8900_. The impedance of the input capacitor at the switching frequency should be very low. Ceramic capacitors with X5R or X7R dielectric are highly recommended due to their small size, low ESR, and small temperature coefficients. For optimum noise immunity and low input voltage ripple, the input capacitor value can be increased. To fully utilize the Q22V input capability of the MAX8900_, the INBP capacitor voltage rating must be 25V or greater. Note that if VIN falls below VBAT, VINBP remains at the VBAT potential (i.e., a -20V at IN does not pull down INBP). Because VINBP never goes negative, it is possible to use a polarized capacitor (Maxim recommends a ceramic capacitor). INBP is a critical discontinuous current path that requires careful bypassing. In the PCB layout, place CINBP as close as possible to the power pins (INBP and PGND) to minimize parasitic inductance. If making connections to the INBP capacitor through vias, ensure that the vias are rated for the expected input current so they do not contribute excess inductance and resistance between the bypass capacitor and the power pins. The expected INBP current is the same as the ISAT (see the Inductor Selection section). See the PCB Layout section for more details. The input capacitor must meet the input ripple current requirement imposed by the step-down converter. Ceramic capacitors are preferred due to their low ESR and resilience to surge currents. Choose the INBP capacitor so that its temperature rise due to ripple-current does not exceed approximately TA = +10NC. For a step-down regulator, the maximum input ripple current is half of the output current. This maximum input ripple current occurs when the step-down converter operates as 50% duty cycle (VIN = 2 x VBAT). The minimum IN capacitor (CIN) is 0.47FF with a voltage rating of 25V or greater. Note that although the MAX8900_ needs only 0.47FF, larger capacitors can be used. Some specifications from USB-IF require a 2.2FF capacitor to have proper handshaking during OTG operation. The BST 29 INBP Capacitor MAX8900A/MAX8900B Other Capacitors Figure 13. Calculated Fast-Charge Current vs. Dropout Voltage 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B capacitor (CBST) is a 0.1FF with a voltage rating of 10V or greater. If CBST is increased then maintain a ratio of less than 1:10 between CBST and CPVL. CBST stores charge to drive the high-side n-channel gate. The minimum AVL capacitor is 0.1FF with a voltage rating of 6.3V. The minimum PVL capacitor is 1.0FF with a voltage rating of 6.3V. Ceramic capacitors with X5R or X7R dielectric are highly recommended due to their small size, low ESR, and small temperature coefficients. U The system must not draw load currents that are greater than IPQ when the battery is less than VPQUTH. U The thermistor node (THM) must be satisfied. Note that if the thermistor is in the battery pack and the pack is removed, the MAX8900_ THM node voltage goes high and disables the charger. If the MAX8900_ is expected to deliver charge without a battery then VTHM must be forced to AVL/2. U The battery node should have enough capacitance to hold the battery voltage to some minimum acceptable system value (VSYSRST) during the done-to-fastcharge state transition time of 100Fs (tDONE2FC). C BAT ILOAD x t DONE2FC VBATREG - VSYSRST Applications Information Certain applications require dynamic programming of the charge current. For example, if the input supply is a USB source, then the system might need to adjust the charge current to support the 100mA and 500mA input current ratings dictated by the USB-IF. Figure 2 illustrates one approach to dynamically program the charge current. By driving the gates of two MOSFET switches to logic-high or logic-low, a microprocessor (FP) connects or disconnects different program resistors. This method allows for four different charge current values ranging from 95mA to 1187mA. When a MOSFET is turned on, its associated resistor is connected to SETI. As resistors are added in parallel, the total resistance from SETI to ground decreases, which causes IFC to increase. In the particular example of a USB input, the circuit of Figure 2 could be leveraged as follows: When a VBUS connect event is detected, the FP can immediately initiate the USB 100mA current mode by setting GPIO[6:4] = 0b000. After the USB transceiver has enumerated with 500mA permission, the FP can initiate the USB 500mA current mode by setting GPIO[6:4] = 0b010. If the USB transceiver detects that a USB suspend is needed, then the FP can reduce the input current to 40FA by setting GPIO[6:4] = 0b001. Alternatively, it is possible that after the VBUS connect event that the USB transceiver determines that there is a dedicated USB wall charger (D+ and D- shorted together) and then the FP can set the charge current to the full capability of the MAX8900_ (1.2A) by setting GPIO[6:4] = 0b110. No-battery operation may be necessary in the application and/or end-of-line testing during production. The MAX8900_ can operate a system without a battery as long as the following conditions are satisfied: U The system must not draw load currents that are greater than IFC. Dynamic Charge Current Programming For example, if the maximum system load without a battery could be 300mA (ILOAD) and the minimum acceptable system voltage is 3.4V (VSYSRST), then the battery node should have at least 37.5FF. C BAT 300mA x 100Fs = 35.7FF 4.2V - 3.4V A battery charger's input is typically very accessible to the end-user (i.e., available on a connector) and can potentially be exposed to very harsh conditions. The MAX8900_ provides for high-reliability solution that can survive harsh conditions seen on its input. Charge-Source Impedance Charge source impedance can vary due to quality of the charge source and the associated connectors. The MAX8900_ operates very nicely with input impedance up to 1I. When high input impedances cause the input voltage to drop, the MAX8900_ simply reduces the charge current to a sustainable level and tries to put as much energy into the battery as possible. If the input voltage falls within the VIN2BAT threshold of the battery voltage, the MAX8900_ shuts down to prevent any current flowing from the battery back to the charger source. The MAX8900_ does not suffer from the self-oscillation problems that plague other chargers when exposed to high-impedance sources. Inductive Kick Often the input source has long leads connecting to the MAX8900_, which, during connection and disconnect, can cause voltage spikes. The lead inductance and the input capacitor create an LC tank circuit. In the event that the LC tank circuit has a high Q (i.e., low series Charge-Source Issues No-Battery Operation 30 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring impedance), the voltage spike could be twice that of the nominal source voltage. In other words, a 6V source with a high-Q LC tank circuit in the cabling can result in a voltage spike as high as 12V. The MAX8900_'s high input absolute maximum voltage rating of +22V to -22V eliminates any concerns about the voltage spikes due to inductive kicking for many applications. In the event that an application may see a high-Q LC tank circuit in the cabling for a supply that is > +11V, a resistor (RIN) must be added in series with CIN to reduce the Q of the tank circuit. The resistor value can be found experimentally by assuming the parasitic inductance (LPAR) of the input cabling is 1FH/m, then use the following equation give a good starting value for RIN: RIN = 2 x L PAR CIN U Excessive ripple voltage on a switch-mode wall charger U USB powered hub that is powered by a wall charger (typically through a barrel connector) that has any of the aforementioned issues U Unregulated charger (passively regulated by the turns ratio of the magnetic's turns ratio) U Automotive environment (9V, 12V, any of the aforementioned in reverse). The MAX8900_ WLP package and bump configuration allows for a small-size low-cost PCB design. Figures 3 and 14 show that the MAX8900_ package's 30 bumps are combined into 18 functional nodes. The bump configuration places all like nodes adjacent to each other to minimize the area required for routing. The bump configuration also allows for a layout that does not use any vias within the WLP bump matrix (i.e., no micro vias). To utilize this no via layout, CEN is left unconnected and the STAT3 pin is not used (2-pin status version). Figure 15 shows the recommended land pattern for the MAX8900_. Figure 16 shows the cross section of the MAX8900_'s bump with detail of the under-bump metal (UBM). The diameter of each pad in the land pattern is close to the diameter of the UBM. This land pattern to UBM relationship is important to get the proper reflow of each solder bump. Underfill is not necessary for the MAX8900_'s package to pass the JESD22-B111 Board Level Drop Test Method for Handheld Electronic Products. JESD22-B111 covers end applications such as cell phones, PDAs, cameras, and other products that are more prone to being dropped during their lifetime due to their size and weight. Please consider using underfill for applications that require higher reliability than what is covered in the JESD22-B111 standard. Careful printed circuit layout is important for minimizing ground bounce and noise. Figure 14 is an example layout of the critical power components for the MAX8900_. The arrangement of the components that are not shown in Figure 14 is less critical. Refer to the MAX8900 Evaluation Kit for a complete PCB layout example. Use the following MAX8900A/MAX8900B PCB Layout An alternative method for estimating LPAR is to measure the frequency of the input voltage spike ringing and then calculate LPAR from the following equation. L PAR = 1 (2 x x fR ) x CIN Overvoltage and Reverse Voltage Protection The MAX8900_ provides for a +22V absolute maximum positive input voltage and a -22V absolute maximum negative input voltage. Excursions to the absolute maximum voltage levels should be on a transient basis only, but can be withstood by the MAX8900_ indefinitely. Situations that typically require extended input voltage ratings include but are not limited to the following: U Inductive kick U Charge source failure U Power surge U Improperly wired wall adapter U Improperly set universal wall adapter U Wall adapter with the correct plug, but wrong voltage U Home-built computer with USB wiring harness connected backwards (negative voltage) U USB connector failure 31 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B list of guidelines in addition to Application Note 1891: Wafer-Level Packaging (WLP) and Its Applications (www. maxim-ic.com/ucsp) to layout the MAX8900_ PCB. The guidelines at the top are the most critical: 1) When the step-down converter's high-side MOSFET turns on, CINBP delivers a high di/dt current pulse to INBP. Because of this high di/dt current pulse, place CINBP close to INBP to minimize the parasitic impedance in the PCB trace. 2) When the step-down converter is increasing the current in the inductor, the high-side MOSFET is on and current flows in the following path: from CINBP into INBP >> out of LX >> through the inductor >> into CS >> out of BAT >> through CBAT and back to CINBP through the ground plane. This current loop should be kept small and the electrical length from the positive terminal of CINBP to INBP should be kept short to minimize parasitic impedance. The electrical length from the negative terminal of CBAT to the negative terminal of CINBP should be short to minimize parasitic impedance. Keep all sensitive signals such as feedback nodes or audio lines outside of this current loop with as much isolation as your design allows. 3) When the step-down converter is decreasing the inductor current, the low-side MOSFET is on and the current flows in the following path: out of LX >> through the inductor >> into CS >> out of BAT >> through CBAT >> into PGND >> out of LX again. This current loop should be kept small and the electrical length from the negative terminal of CBAT to PGND should be short to minimize parasitic impedance. Keep all sensitive signals such as feedback nodes or audio lines outside of this current loop with as much isolation as your design allows. 4) The LX node voltage switches between INBP and PGND during the operation of the step-down converter. Minimize the stray capacitance on the LX node to maintain good efficiency. Also, keep all sensitive signals such as feedback nodes or audio lines away from LX with as much isolation as your design allows. 5) In Figure 14, the CS node is connected to the second layer of metal with vias. Use low-impedance vias that are capable of handling 1.5A of current. Also, keep the routing inductor current path on layer 2 just underneath the inductor current path on layer 1 to minimize impedance. 6) Both CBST and CPVL deliver current pulses for the MAX8900_'s MOSFET drivers. These components should be placed as shown in Figure 14 to minimize parasitic impedance. 7) Each of the MAX8900_ bumps has approximately the same ability to remove heat from the die. Connect as much metal as possible to each bump to minimize the BJA associated with the MAX8900_. See the Thermal Management section for more information on BJA. In Figure 14, many of the top layer bump pads are connected together in top metal. When connecting bumps together with top layer metal, the solder mask must define the pads from 180Fm to 210Fm as shown in Figure 15. When using solder mask defined pads, please double check the solder mask openings on the PCB Gerber files before ordering boards as some PCB layout tools have configuration settings that automatically oversize solder mask openings. Also, explain in the PCB fabrication notes that the solder mask is not to be modified. Occasionally, optimization tools are used at the PCB fabrication house that modify solder masks. Layouts that do not use solder mask defined pads are possible. When using these layouts, adhere to the recommendations A through G above. Figure 14. Power PCB Layout Example 32 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B EPOXY TOP VIEW SCALE DRAWING 5x6 BUMP ARRAY (30 BUMPS) 1 A B C D E A B D E 2 3 4 5 6 WAFER A: FINISHED PAD DIAMETER: 180m (min) 210m (max) A B C B: PAD PITCH: 400m C: HEIGHT: 1.6mm D: WIDTH: 2.0mm F EPOXY COPPER PILLAR (UBM) EPOXY COPPER PILLAR (UBM) G EPOXY 1oz COPPPER PAD PCB 1oz COPPPER PAD Figure 15. Recommended Land Pattern E: BUMP DIAMETER: 260m F: COPPER PILLAR (UBM) WIDTH: 210m G: COPPER PILLAR PITCH: 400m Figure 16. Bump Cross Section and Copper Pillar Detail Chip Information PROCESS: BiCMOS 33 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring MAX8900A/MAX8900B Package Information For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE 30 WLP PACKAGE CODE W302A2+1 DOCUMENT NO. 21-0211 WLP PKG.EPS 34 1.2A Switch-Mode Li+ Chargers with 22V Input Rating and JEITA Battery Temperature Monitoring Revision History REVISION NUMBER 0 1 REVISION DATE 1/10 3/10 Initial release Corrected various items DESCRIPTION PAGES CHANGED -- 1, 4, 5, 15, 30 MAX8900A/MAX8900B Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 35 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc. |
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