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LTC3531/ LTC3531-3.3/LTC3531-3 200mA Buck-Boost Synchronous DC/DC Converters FEATURES

DESCRIPTIO

Regulated Output with Input Above, Below or Equal to the Output Single Inductor Up to 90% Efficiency VIN Range: 1.8V to 5.5V 200mA at 3.3VOUT from 3.6V Input 125mA at 3VOUT from 2.5V Input Fixed VOUT Versions (TSOT, DFN): 3.3V, 3V Adjustable VOUT Version (DFN): 2V to 5V Burst Mode(R) Operation, No External Compensation Ultra Low Quiescent Current: 16A, Shutdown Current <1A Only 3 External Components Required Short-Circuit Protection Output Disconnect in Shutdown Available in 6-Pin ThinSOT and 3mm x 3mm DFN Packages
The LTC(R)3531/LTC3531-3.3/LTC3531-3 are synchronous buck-boost DC/DC converters that operate from input voltages above, below or equal to the output voltage. The topology incorporated in the ICs provides a continuous transfer through all operating modes, making the product ideal for single cell Li-Ion and multicell alkaline or nickel applications. The converters operate in Burst Mode, minimizing solution footprint and component count as well as providing high conversion efficiency over a wide range of load currents. The devices include two 0.5 N-channel MOSFET switches and two P-channel switches (0.5, 0.8). Quiescent current is typically 16A, making the parts ideal for battery power applications. Other features include a <1A shutdown current, current limiting, thermal shutdown and output disconnect. The parts are offered in a 6-pin ThinSOTTM package for fixed voltage versions or a 3mm x 3mm DFN package for fixed and adjustable versions.
, LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Burst Mode is a registered trademark of Linear Techonology Corporation. ThinSOT is a trademark of Linear Techonology Corporation. Protected by U.S. Patents including 6166527.
APPLICATIO S

Handheld Instruments MP3 Players Handheld computers PDA/GPS
TYPICAL APPLICATIO
10H SW1 VIN
100 95 90 EFFICIENCY (%) VIN 3.1V TO 4.2V Li-Ion SW2 VOUT VOUT 3.3V 160mA 10F SHDN GND 70
3531 TA01a
85 80 75
+
LTC3531-3.3 2.2F
65 ON OFF 60 1.5 2 2.5 3.3VOUT AT 100mA 3 3.5 4 4.5 INPUT VOLTAGE (V) 5 5.5
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Efficiency vs VIN
BOOST MODE BUCK MODE 4SW MODE
3531 TA01b
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LTC3531/ LTC3531-3.3/LTC3531-3 ABSOLUTE
(Note 1)
AXI U RATI GS
Storage Temperature Range................... -65C to 125C Lead Temperature (TS6, Soldering, 10 sec) .......... 300C
VIN, VOUT, SWA, SWB, SHDN Voltage .............-0.3 to 6V SWA, SWB Voltage, <100ns Pulse ..................-0.3 to 7V Operating Temperature Range (Note 2) ... -40C to 85C
PACKAGE/ORDER I FOR ATIO
TOP VIEW SW2 1 GND, PGND 2 VOUT 3 6 SW1 5 VIN 4 SHDN
S6 PACKAGE 6-LEAD PLASTIC TSOT-23 TJMAX = 125C, JA = 102C/W
ORDER PART NUMBER LTC3531ES6-3.3 LTC3531ES6-3
S6 PART MARKING LTBWM LTCBK
Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges.
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = 3.6V VOUT = 3.3V unless otherwise noted.
PARAMETER VIN Minimum Startup Voltage VOUT Regulation Output Voltage (3.3V Version) Output Voltage (3V Version) FB Voltage (Adj Version) FB Input Current (Adj Version) Operating Current Quiescent Current in Sleep: Shutdown Current Switch Performance NMOS Switch Leakage PMOS Switch Leakage NMOS B, C RDSON PMOS A RDSON CONDITIONS
ELECTRICAL CHARACTERISTICS
No Load No Load No Load VFB = 1.225V VIN VOUT VIN VIN = 5V, VOUT = 3.6V, FB = 1.3V VOUT = 3.6V SHDN = 0V, VOUT = 0V Switches B and C Switches A and D VIN = 5V VIN = 5V
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TOP VIEW SW1 1 VIN 2 GND 3 SHDN 4 9 8 7 6 5 PGND SW2 VOUT FB*
DD PACKAGE 8-LEAD (3mm x 3mm) PLASTIC DFN TJMAX = 125C, JA = 43C/W EXPOSED PAD IS GND (PIN 9), MUST BE SOLDERED TO PCB *NC FOR LTC3531-3.3V, LTC3531-3.0V.
ORDER PART NUMBER LTC3531EDD LTC3531EDD-3.3 LTC3531EDD-3
DD PART MARKING LBVC LBWH LCBV
MIN
TYP 1.65
MAX 1.8 3.39 3.09 1.25 50 30 10 1 2 2
UNITS V V V V nA A A A A A
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3.25 2.95 1.20
3.32 3.02 1.225 1 16 6
0.2 0.2 0.5 0.5
LTC3531/ LTC3531-3.3/LTC3531-3
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = 3.6V VOUT = 3.3V unless otherwise noted.
PARAMETER PMOS D RDSON (3.3V Version) PMOS D RDSON (3V Version) Peak Current Limit SHDN SHDN Input Threshold SHDN Hysteresis SHDN Leakage Current CONDITIONS VOUT = 3.1V VOUT = 2.8V L = 10H, VIN = 5V MIN TYP 0.8 0.9 365 1 60 0.01 MAX UNITS mA V mV A
ELECTRICAL CHARACTERISTICS
295 0.4
460 1.4 1
VSHDN
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction temperature may result in device degradation or failure. Note 3: The LTC3531 is guaranteed to meet performance specifications from 0C to 70C. Specifications over the -40C to 85C operating temperature range are assured by design, characterization and correlation with statistical process controls.
TYPICAL PERFOR A CE CHARACTERISTICS
Maximum IOUT vs VIN (3.3V Version)
350 300 MAXIMUM IOUT (mA) 250 CURRENT (mA) 200 150 100 50 0 1.5 L = 10H VOUT = 3.3V 450 400 350 300 250 200 150 100 50 2 2.5 3 3.5 VIN (V)
3531 G01
CURRENT (A)
4
180 160
IIN Short Circuit vs VIN
VRIPPLE PEAK-PEAK (mV)
140 120 IIN (mA) 100 80 60 40 20 0 1.5 2 2.5 3 3.5 VIN (V)
3531 G04
50 40 30 20 10 0 50mA LOAD 1.5 2 2.5 3 3.5 4 VIN (V) 4.5 5 5.5 22F
VOUT (V)
4
UW
4.5 5 4.5 5
TA = 25C unless otherwise specified. Sleep Currents
20 18 IVIN
IPEAK, IVALLEY, IZERO vs VIN
L = 10H IPEAK
16 14 12 10 8 6 4
IVALLEY
IVOUT
IZERO 2 2.5 3 3.5 VIN (V)
3531 G02
2 0 4 4.5 5 5.5 1.5 2 2.5 3 3.5 4 VIN (V) 4.5 5 5.5
5.5
0 1.5
3531 G03
VOUT Ripple vs COUT (3.3V Version)
100 90 80 70 60 3.30 10F 3.35 3.40
Load Regulation vs COUT (3.3V Version)
10F
22F 3.25 47F
3.20 VIN = 3.6V 3.15 1 0.1
5.5
10 100 LOAD CURRENT (mA)
1000
3521 G06
3531 G05
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LTC3531/ LTC3531-3.3/LTC3531-3 TYPICAL PERFOR A CE CHARACTERISTICS
Start-Up into Resistive Load L = 10H
30 28 26 FREQUENCY (kHz) 24 RMIN () 22 20 18 16 14 12 10 1.5 2 2.5 3 3.5 4 VIN (V) 4.5 5 5.5 0.1 1.5 2 2.5 3 3.5 4 VIN (V) 4.5 5 5.5 3.250 -40 -20 60 0 20 40 TEMPERATURE (C) 80 100
3531 G09
VOUT (V)
Switch On Resistances
1000 900 800 700 600 500 400 -40 A (PMOS) VIN = 5V VOUT = 3.3V 400 D (PMOS) 350
CURRENT (mA)
VOLTAGE (V)
RDSON (m)
B,C (NMOS) 60 0 20 40 TEMPERATURE (C) 80 100
-20
4
UW
3531 G07 3531 G10
TA = 25C unless otherwise specified. VOUT Regulation vs Temperature (3.3V Version)
3.350 VIN = 3.6V ILOAD = 10mA
Burst Frequency vs Load (3.3V Version)
1000 L = 10H COUT = 10F 50mA 10mA 10 1mA 1 0.5mA 3.275 3.300 5mA
100
3.325
3531 G08
IPEAK, IVALLEY vs Temperature
1 IPEAK 0.9 300 250 200 150 100 50 0 -40 -20 0 IZERO 40 60 20 TEMPERATURE (C) 80 100 2.5VIN 3.3VOUT 10H IVALLEY 0.8
SHDN Pin Threshold and Hysteresis
OPERATING
0.7
SHUTDOWN
0.6
0.5 - 40
- 20
60 0 20 40 TEMPERATURE (C)
80
100
3531 G12
3531 G11
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LTC3531/ LTC3531-3.3/LTC3531-3 TYPICAL PERFOR A CE CHARACTERISTICS
Buck Mode at 5VIN, 3.3VOUT 200mA
SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV L = 10H COUT = 22F 5s/DIV
3531 G13
Buck Mode Waveforms at 5VIN, 3.3VOUT 20mA
SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV
L = 10H COUT = 22F
4 Switch Mode Waveforms at 3.6VIN, 3.3VOUT 100mA
SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV
L = 10H COUT = 22F
UW
TA = 25C unless otherwise specified.
Buck Mode at 5VIN, 3.3VOUT 100mA
SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV L = 10H COUT = 22F 5s/DIV
3531 G14
4 Switch Mode Waveforms at 3.6VIN, 3.3VOUT 200mA
5s/DIV
3531 G15
L = 10H COUT = 22F
5s/DIV
3531 G16
4 Switch Mode Waveforms at 3.6VIN, 3.3VOUT 20mA
SW1 SW2 VOUT (AC) IL
5s/DIV
3531 G17
L = 10H COUT = 22F
5s/DIV
3531 G18
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LTC3531/ LTC3531-3.3/LTC3531-3 TYPICAL PERFOR A CE CHARACTERISTICS
Boost Mode Waveforms at 2.5VIN, 3.3VOUT 100mA
SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV
L = 10H COUT = 22F
Shorted Output
SW1 5V/DIV SW2 5V/DIV VOUT (AC) 50mV/DIV IL 200mA/DIV
L = 10H COUT = 22F VIN = 5
3.6VIN, 3.3VOUT Load Step 200mA to 80mA
100mA LOAD 20mA LOAD VOUT (AC) 20mV/DIV 20mA LOAD SW1 2V/DIV IL 200mA/DIV SW2 2V/DIV
COUT = 22F
6
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TA = 25C unless otherwise specified.
Boost Mode Waveforms at 2.5VIN, 3.3VOUT 20mA
5s/DIV
3531 G19
L = 10H COUT = 22F
5s/DIV
3531 G20
Start-Up into 50mA Load at 3.3 VOUT (Shows Start, Buck, Then 4sw Modes)
200mA/DIV
VOUT 1V/DIV IL 200mA/DIV
1s/DIV
3531 G21
25s/DIV
3531 G22
SW1 and SW2 Close-Up in Four Switch Mode
25s/DIV
3531 G23
VIN = 3.6V VOUT = 3.3V
200ns/DIV
3531 G24
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LTC3531/ LTC3531-3.3/LTC3531-3 PI FU CTIO S
SW2 (Pin 1/Pin 7): Buck-Boost Switch Pin Where Internal Switches C and D are Connected. An optional Schottky diode can be connected from SW2 to VOUT for a moderate efficiency improvement. Minimize trace length to keep EMI down. GND (Pin 2/Pin 3): Signal Ground for the IC. PGND (Pin 2/Pin 8): Power Ground for the IC. (Shared on ThinSOT version) VOUT (Pin 3/Pin 6): Output of the Buck-Boost Synchronous Rectifier. A filter capacitor is placed from VOUT to GND. A ceramic bypass capacitor is recommended as close to the VOUT and GND pins as possible. SHDN (Pin 4/Pin 4): External Shutdown Pin. An applied voltage of < 0.4V shuts down the converter. A voltage above >1.4V will enable the converter.
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ThinSOT/DFN Packages
VIN (Pin 5/Pin 2): Input Supply Pin for the Buck-Boost Converter. A minimum 2.2F Ceramic Capacitor should be placed between VIN and GND. FB (NA/Pin 5): Feedback Pin for the Adjustable Version. Connect the resistor divider tap here. The output voltage can be adjusted from 2V to 5V. R2 VOUT = 1 . 225 1+ R1 SW1 (Pin 6/Pin 1): Buck-Boost Switch Pin Where Internal Switches A and B are Connected. Connect the inductor from SW1 to SW2. Exposed Pad (Pin 9, DFN): Solder to PCB ground for optimal thermal performance.
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LTC3531/ LTC3531-3.3/LTC3531-3 BLOCK DIAGRA W
SW1 SW2 SW A VIN SW D VOUT SW B GATE DRIVERS AND ANTICROSS CONDUCTION SW C IZERO/IVALLEY DETECT PEAK CURRENT LIMIT STATE MACHINE AND LOGIC UVLO 1.65V VOUT COMPARATOR SHDN SHUTDOWN THERMAL SHUTDOWN FB R1 NOT BONDED FOR 3.3V AND 3V VERSIONS
3531 BD
VBEST BUCK, 4SW, BOOST VBEST AND MODE DETECT VIN VOUT
365mA
VIN
1.225V VREF
R2
PGND GND COMBINED FOR TSOT
INTERNAL R1s AND R2s DISABLED FOR ADJ VERSION
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LTC3531/ LTC3531-3.3/LTC3531-3 OPERATIO
The LTC3531, LTC3531-3.3 and LTC3531-3 synchronous buck-boost converters utilize a Burst Mode control technique to achieve high efficiency over a wide dynamic range of load currents. A 2% accurate comparator is used to monitor the output voltage. If VOUT is above its programmed reference threshold no switching occurs and only quiescent current is drawn from the power source (sleep mode). When VOUT drops below the reference threshold the IC "wakes up", switching commences, and the output capacitor is charged. The value of the output capacitor, the load current, and the comparator hysteresis (~1%) determines the number of current pulses required to pump-up the output capacitor before the part returns to sleep. In order to determine the best operating mode for the converter, the LTC3531 contains a second comparator that monitors the relative voltage difference between VIN and VOUT. Input and output voltages in the various modes as well as typical inductor currents are shown in Figure 1. Regions of the current waveforms where switches A and D are on provide the highest efficiency since energy is transferred directly from the input source to the output. Boost Mode If VIN is ~400mV below VOUT, the LTC3531 operates in boost or step-up mode. Referring to Figure 1 (left side) when VOUT falls below its regulation voltage, switches A and C are turned on (VIN is applied across the inductor) and current is ramped until IPEAK is detected. When this
VIN
A
SW1
B
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occurs, C is turned off, D is turned on and current is delivered to the output capacitor (VIN - VOUT is applied across the inductor). Inductor current falls when D is on, until an IVALLEY is detected. Terminating at IVALLEY, rather than IZERO, results in an increased load current capability for a given peak current. This AC then AD switch sequence is repeated until the output is pumped above its regulation voltage, a final IZERO is detected, and the part returns to sleep mode (IVALLEY is ignored and IZERO is used in all modes once VOUT is above its programmed value). 4-Switch Mode If (VOUT - 400mV) < ~VIN < (VOUT + 800mV), the LTC3531 operates in 4-switch step-up/down mode. Returning to Figure 1 (center) when VOUT falls below its regulation voltage, switches A and C are turned on and current is ramped until IPEAK is detected. As with Boost Mode operation, C is then turned off, D is turned on and current is delivered to the output. When A and D are on, the inductor current slope is dependant on the relationship between VIN, VOUT, and the RDSON of the switches. In 4-switch mode, a tOFF timer (approximately 3s) is used to terminate the AD pulse. Once the tOFF timer expires, switch A is turned off, B is turned on and inductor current is ramped down (VOUT is applied across the inductor) until IVALLEY is detected. This sequence is repeated until the output is regulated, BD switches are turned on, and a final IZERO is detected. Anticross conduction circuitry in all modes ensures the P-channel MOSFET and N-channel MOSFET switch pairs (A and B or D and C) are never turned on simultaneously.
VIN VOUT VOUT D VIN L SW2 IMAX C IPEAK tOFF IVALLEY tOFF tOFF IZERO AC AD AC AD BOOST MODE AC AD BD AC AD BD AC 4SW MODE AD BD AD BD AD BD BUCK MODE
3531 F01
Figure 1. Voltage and Current Waveforms
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LTC3531/ LTC3531-3.3/LTC3531-3 OPERATIO
Buck Mode If VIN is ~800mV above VOUT, the LTC3531 operates in buck or step-down mode. The higher offset between VIN and VOUT (800mV) is required to ensure sufficient magnetizing voltage across the inductor when the RDSONS are taken into account. At the beginning of a buck mode cycle (Figure 1 right side) switches A and D are turned on (VIN - VOUT is applied across the inductor), current is delivered to the output and ramped up until IPEAK is detected. When this occurs, A is turned off, B is turned on and inductor current falls (-VOUT across the inductor) until an IVALLEY is detected. This AD then BD switch sequence is repeated until the output is pumped above its regulation voltage, a final IZERO is detected, and the part returns to sleep mode. Start-Up Mode Before VOUT reaches approximately 1.6V, the D switch is disabled and its body diode is used to transfer current to the output capacitor. In start-up mode, the IVALLEY/IZERO sense circuit is disabled and an alternate algorithm is used to control inductor current. When the LTC3531 is brought out of shutdown (assuming VOUT is discharged) switches A and C are turned on until the inductor current reaches IPEAK. The AC switches are then turned off and inductor current flows to the output through the B switch and D body diode. The period for the B switch/D body diode is controlled by the tOFF timer to ~800nS. This sequence of AC switch-on to IPEAK then B switch and D body diode for ~800ns is repeated until VOUT reaches ~1.6V. Once this
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threshold is reached, the LTC3531 will transfer through the required modes until VOUT is brought into regulation. Due to propagation delays in the sense circuitry, the magnitudes of the IPEAK, IVALLEY, and IZERO currents may shift depending on VIN, VOUT and operating mode. OTHER LTC3531 FEATURES Shutdown: The part is shut down by pulling SHDN below 0.4V, and made active by pulling the pin up to VIN or VOUT. Note that SHDN can be driven above VIN or VOUT, as long as it is limited to less than 6V. Output Disconnect and Inrush Limiting: The LTC3531 is designed to allow true output disconnect by opening both P-channel MOSFET rectifiers. This allows VOUT to go to zero volts during shutdown, drawing no current from the input source. It also provides inrush current limiting at turn-on, minimizing surge currents seen by the input supply. Thermal Shutdown: If the die temperature reaches approximately 150C, the part will go into thermal shutdown and all switches will be turned off. The part will be enabled again when the die temperature has dropped by 10C (nominal). To deliver the power that the LTC3531 is capable of, it is imperative that a good thermal path be provided to dissipate the heat generated within the package. It is recommended that multiple vias in the printed circuit board be used to conduct heat away from the IC and into a copper plane with as much area as possible. Soldering the Exposed Pad to the GND plane (DFN version) is recommended to improve thermal performance.
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LTC3531/ LTC3531-3.3/LTC3531-3 APPLICATIO S I FOR ATIO
Component Selection Only three power components are required to complete the design of the buck-boost converter, VOUT programming resistors are needed for the adjustable version. The high operating frequency and low peak currents of the LTC3531 allow the use of low value, low profile inductors and tiny external ceramic capacitors. Inductor Selection For best efficiency, choose an inductor with high frequency core material, such as ferrite, to reduce core loses. The inductor should have low DCR (DC resistance) to reduce the I2R losses, and must be able to handle the peak inductor current without saturating. A 10H to 22H inTable 2. Inductor Vendor Information
Supplier COEV Coilcraft Series DN4835 MSS4020 LPO3310 DS1608 LQH43CN LQH32CN CDRH4D18 CDRH3D16/HP D312C D412C DB320C Phone (800) 227-7040 (847) 639-6400 Website www.coev.net www.coilcraft.com
Murata Sumida Toko
USA: (814) 237-1431 www.murata.com (800) 831-9172 USA: (847) 956-0666 www.sumida.com Japan: 81-3-3607-5111 (847) 297-0070 www.tokoam.com
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ductor value with a >500mA current rating and <400m DCR is recommended. For applications where radiated noise is a concern, a toroidal or shielded inductor can be used. Table 2 contains a list of inductor manufacturers. Capacitor Selection The buck-boost convertor requires two capacitors. Ceramic X5R types will minimize ESL and ESR while maintaining capacitance at rated voltage over temperature. The VIN capacitor should be at least 2.2F. The VOUT capacitor should be between 4.7F and 22F. A larger output capacitor should be used if lower peak to peak output voltage ripple is desired. A larger output capacitor will also improve load regulation on VOUT. See Table 3 for a list of capacitor manufacturers for input and output capacitor selection.
Table 3. Capacitor Vendor Information
Supplier AVX Murata Phone (803) 448-9411 USA: (814) 237-1431 (800) 831-9172 Sanyo POSCAP (619) 661-6322 Taiyo Yuden X5R (408) 573-4150 TDK X5R (847) 803-6100 Series X5R X5R Website www.avxcorp.com www.murata.com www.sanyovideo.com www.taiyo-yuden.com www.component.tdk.com
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LTC3531/ LTC3531-3.3/LTC3531-3 APPLICATIO S I FOR ATIO U
COUT VIN CIN VOUT L VOUT - 3 4 - SHDN 5 - VIN GND - 2 6 - SW1 SW2 - 1 SOT PIN-OUT GND
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SHUTDOWN
12
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GND
Recommended Layout (SOT Versions)
LTC3531/ LTC3531-3.3/LTC3531-3 TYPICAL APPLICATIO S
5V/Li-Ion to 3.3V with ThinSOT (3.3V Version)
95 10H 90 EFFICIENCY (%) VIN 3.1V TO 5V 5V/Li-Ion SW1 VIN SW2 VOUT VOUT 3.3V 160mA 10F SHDN GND
3531 TA02a
+ -
LTC3531-3.3 2.2F
ON OFF
10H 85 EFFICIENCY (%) VIN 1.8V TO 3.2V 2 x AA ALKALINE SW1 SW2 VOUT VOUT 3V 80mA 10F SHDN GND
3531 TA03a
+ - + -
VIN
LTC3531-3 2.2F
ON OFF 60 0.1 1 10 100 LOAD CURRENT (mA) 0.1 1000
3531 TA03b
10H 90 EFFICIENCY (%) USB 4.35V TO 5.25V SW1 VIN 4.7F 2.2F 1 SHDN SW2 VOUT R2 1M FB GND R1 324k
3531 TA04a
LTC3531
ON OFF 65 0.1 1 10 100 LOAD CURRENT (mA) 0.1 1000
3531 TA04b
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100 4.4VIN 5VIN POWER LOSS (mW) 10 3.6VIN
85 80 75 POWER LOSS AT 3.6VIN 70 65 0.1
3.1VIN 1
1
10 100 LOAD CURRENT (mA)
0.1 1000
3531 TA02b
2 AA Alkaline to 3V with ThinSOT (3V Version)
90 100
POWER LOSS (mW)
80 75 70 65
2.5VIN 3.2VIN 1.8VIN POWER LOSS AT 3.2VIN
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1
USB to 5V with 3 x 3 DFN (Adjustable Version)
95 100
EFFICIENCY POWER LOSS (mW) 10
VOUT 5V 200mA 10F
85 80 POWER LOSS 75 70
1
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LTC3531/ LTC3531-3.3/LTC3531-3 PACKAGE DESCRIPTIO U
S6 Package 6-Lead Plastic TSOT-23
(Reference LTC DWG # 05-08-1636)
2.90 BSC (NOTE 4) 1.22 REF 1.4 MIN 2.80 BSC 1.50 - 1.75 (NOTE 4) PIN ONE ID 0.95 BSC 0.30 - 0.45 6 PLCS (NOTE 3) 0.80 - 0.90 0.20 BSC 1.00 MAX DATUM `A' 0.01 - 0.10 0.09 - 0.20 (NOTE 3)
NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING
0.62 MAX
0.95 REF
3.85 MAX 2.62 REF
RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR
0.30 - 0.50 REF
1.90 BSC
S6 TSOT-23 0302
4. DIMENSIONS ARE EXCLUSIVE OF MOLD FLASH AND METAL BURR 5. MOLD FLASH SHALL NOT EXCEED 0.254mm 6 JEDEC PACKAGE REFERENCE IS MO-193
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LTC3531/ LTC3531-3.3/LTC3531-3 PACKAGE DESCRIPTIO U
DD Package 8-Lead Plastic DFN (3mm x 3mm)
(Reference LTC DWG # 05-08-1698)
R = 0.115 TYP 5 0.675 0.05 0.38 0.10 8 3.00 0.10 (4 SIDES) PACKAGE OUTLINE 0.25 0.05 0.50 BSC 2.38 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-1) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON TOP AND BOTTOM OF PACKAGE PIN 1 TOP MARK (NOTE 6)
(DD8) DFN 1203
3.5 0.05 1.65 0.05 2.15 0.05 (2 SIDES)
1.65 0.10 (2 SIDES)
0.200 REF
0.75 0.05
4 0.25 0.05 2.38 0.10 (2 SIDES)
1 0.50 BSC
0.00 - 0.05
BOTTOM VIEW--EXPOSED PAD
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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LTC3531/ LTC3531-3.3/LTC3531-3 TYPICAL APPLICATIO S
Complete USB/Li-Ion Powered System with 3.3VOUT and Linear Charger
5V (NOM) FROM USB CABLE LTC4055 IN1 IN2 HPWR SUSPEND USB POWER SUSP BAT OUT CHRG ACPR VNTC TIMER CLPROG GND PROG 100k 100k 0.1F C1 22F 3.1V TO 5.25V SW1 VIN SW2 VOUT VOUT 3.3V 160mA C2 10F
3531 TA05
+ Li-Ion -
SHDN WALL NTC
C1, C2: TAIYO YUDEN JMK316BJ106ML L1: MURATA LQH43CN100K03 (650mA 0.24)
RELATED PARTS
PART NUMBER LT1930/LT1930A LTC3400/LTC3400B LTC3401/LTC3402 LTC3405/LTC3405A LTC3406/LTC3406B LTC3421 LTC3422 LTC3426 LTC3428 LTC3429 LTC3440 LTC3441 LTC3442 LTC3443 LTC3458 LTC3458L LTC3459 LTC3525/LTC3525-3.3/ LTC3525-5 DESCRIPTION 1A (ISW), 1.2MHz/2.2MHz, High Efficiency Step-Up DC/DC Converter 600mA (ISW), 1.2MHz Synchronous Step-Up DC/DC Converter 1A/2A (ISW), 3MHz Synchronous Step-Up DC/DC Converter 300mA (IOUT), 1.5MHz Synchronous Step-Down DC/DC Converter 600mA (IOUT), 1.5MHz Synchronous Step-Down DC/DC Converter 3A (ISW), 3MHz Synchronous Step-Up DC/DC Converter 1.5A (ISW), 3MHz Synchronous Step-Up DC/DC Converter 2A (ISW), 1.2MHz Step-Up DC/DC Converter in SOT-23 4A (ISW), 1.2MHz Step-Up DC/DC Converter 600mA (ISW), 500kHz Synchronous Step-Up DC/DC Converter 600mA (IOUT), 2MHz Synchronous Buck-Boost DC/DC Converter 600mA (IOUT), 2MHz Synchronous Buck-Boost DC/DC Converter 2MHz Synchronous Buck-Boost with Auto-Burst 1.2A (IOUT), 600kHz Synchronous Buck-Boost DC/DC Converter 1.4A, 1.5MHz Synchronous Step-Up DC/DC Converter 1.7A, 1.5MHz Synchronous Step-Up DC/DC Converter 10V Micropower Synchronous Step-Up DC/DC Converter 400mA (ISW), Synchronous Step-Up DC/DC Converter with Output Disconnect COMMENTS VIN: 2.6V to 16V, VOUT(MAX) = 34V, IQ = 4.2mA/5.5mA, ISD < 1A, ThinSOT Package VIN: 0.85V to 5V, VOUT(MAX) = 5V, IQ = 19A/300A, ISD < 1A, ThinSOT Package VIN: 0.5V to 5V, VOUT(MAX) = 6V, IQ = 38A, ISD < 1A, MS Package VIN: 2.7V to 6V, VOUT(MIN) = 0.8V, IQ = 20A, ISD 1A, MS10 Package VIN: 2.5V to 5.5V, VOUT(MIN) = 0.6V, IQ = 20A, ISD 1A, ThinSOT Package VIN: 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 12A, ISD < 1A, QFN Package VIN: 0.5V to 4.5V, VOUT(MAX) = 5.25V, IQ = 25A, ISD < 1A, 3mm x 3mm DFN Package VIN: 1.6V to 5V, VOUT up to 5.5V VIN: 1.6V to 5V, VOUT up to 5.5V VIN: 0.5V to 4.4V, VOUT(MIN) = 5V, IQ = 20A, ISD < 1A, QFN Package VIN: 2.5V to 5.5V, VOUT(MIN) = 5.5V, IQ = 25A, ISD < 1A, MS, DFN Packages VIN: 2.5V to 5.5V, VOUT(MIN) = 5.5V, IQ = 25A, ISD < 1A, DFN Package VIN: 2.4V to 5.5V, VOUT up to 5.25V VIN: 2.4V to 5.5V, VOUT(MIN) = 5.25V, IQ = 28A, ISD < 1A, MS Package VIN: 1.5V to 6V, VOUT up to 7.5V VIN: 1.5V to 6V, VOUT up to 6V VIN: 1.5V to 5.5V, VOUT up to 10V VIN: 0.5V to 4.5V, IQ = 7A, ISD < 1A, 2mm x 2mm SC70 Package
3531f
16 Linear Technology Corporation
(408) 432-1900
1630 McCarthy Blvd., Milpitas, CA 95035-7417
FAX: (408) 434-0507 www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2005
U
VOUT: USB OR BATTERY
OTHER DC/DC
L1 10H
LTC3531-3.3 SHDN GND
LT 1105 * PRINTED IN USA

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