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19-0541; Rev 3; 3/10
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages
General Description
The MAX6782-MAX6790 are low-power, 1% accurate, dual-/triple-/quad-level battery monitors offered in small TDFN and TQFN packages. These devices are ideal for monitoring single lithium-ion (Li+) cells, or multicell alkaline/NiCd/NiMH power sources. These devices feature fixed and adjustable hysteresis options to eliminate output chattering associated with battery-voltage monitors. The MAX6782/MAX6783 offer four battery monitors in a single package with factory-set (0.5%, 5%, 10%) or adjustable hysteresis. The MAX6784/MAX6785 provide three battery monitors with factory-set (0.5%, 5%, 10%) or adjustable hysteresis. The MAX6786/MAX6787/ MAX6788 offer two battery monitors with external inputs for setting the rising and falling thresholds, allowing external hysteresis control. The MAX6789/MAX6790 feature quad-level overvoltage detectors with complementary outputs. The MAX6782-MAX6790 are offered with either open-drain or push-pull outputs. The MAX6782/MAX6784/MAX6786/ MAX6789 are available with push-pull outputs while the MAX6783/MAX6785/MAX6787/MAX6790 are available with open-drain outputs. The MAX6788 is available with one open-drain output and one push-pull output (see the Selector Guide). This family of devices is offered in spacesaving TDFN and TQFN packages and is fully specified over the -40C to +85C extended temperature range.
Features
o 1% Accurate Threshold Specified Over Full Temperature Range o Dual-/Triple-/Quad, Low-Battery Output Options o Low 5.7A Battery Current o Open-Drain or Push-Pull Outputs o Fixed or Adjustable Hysteresis o Low Input Bias Current o Guaranteed Valid Low-Battery-Output Logic State Down to VBATT = 1.05V o Reverse-Battery Protection o Immune to Short Battery Transients o Fully Specified from -40C to +85C o Small TDFN and TQFN Packages
MAX6782-MAX6790
Ordering Information
PART MAX6782TE_+ MAX6783TE_+ MAX6784TC_+ MAX6785TC_+ TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 16 TQFN-EP* 16 TQFN-EP* 12 TQFN-EP* 12 TQFN-EP*
Applications
Battery-Powered Systems (Single-Cell Li+ or Multicell NiMH, NiCd, Alkaline) Cell Phones/Cordless Phones Pagers Portable Medical Devices PDAs Electronic Toys MP3 Players
Ordering Information continued at end of data sheet. +Denotes a lead(Pb)-free/RoHS-compliant package. *EP = Exposed pad. The MAX6782/MAX6783/MAX6784/MAX6785 are available with factory-trimmed hysteresis. Specify trim by replacing "_" with "A" for 0.5%, "B" for 5%, or "C" for 10% hysteresis. Pin Configuration and Typical Operating Circuit appear at end of data sheet.
Selector Guide
PART MAX6782TE_+ MAX6783TE_+ MAX6784TC_+ MAX6785TC_+ MAX6786TA+ MAX6787TA+ MAX6788TA+ MAX6789TB+ MAX6790TB+ MONITOR LEVEL 4 4 3 3 2 2 2 4 4 LBO OUTPUT Quad Quad Triple Triple Dual Dual Dual -- -- OV -- -- -- -- -- -- -- Single Single OV -- -- -- -- -- -- -- Single Single OUTPUT TYPE Push-Pull Open Drain Push-Pull Open Drain Push-Pull Open Drain Push-Pull/Open Drain Push-Pull Open Drain HYSTERESIS Fixed/Adj Fixed/Adj Fixed/Adj Fixed/Adj Adj Adj Adj -- --
Note: All devices are available in tape and reel in 2.5k increments. For tape and reel orders, add a "T" after the "+" to complete the part number.
________________________________________________________________ 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.
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages MAX6782-MAX6790
ABSOLUTE MAXIMUM RATINGS
(All voltages referenced to GND.) BATT.........................................................................-0.3V to +6V IN1-IN4, LBH1, LBL1, LBH2, LBL2 ..................-0.3V to Min ((VBATT + 0.3V) and +6V) HADJ1-HADJ4, REF .......-0.3V to Min ((VBATT + 0.3V) and +6V) LBO1-LBO4 (push-pull) ..-0.3V to Min ((VBATT + 0.3V) and +6V) LBO1-LBO4 (open drain).........................................-0.3V to +6V Input Current (all pins) ........................................................20mA Output Current (all pins) .....................................................20mA Continuous Power Dissipation (TA = +70C) 8-Pin TDFN (derate 23.8mW/C above +70C) ..........1905mW 10-Pin TDFN (derate 24.4mW/C above +70C) ........1951mW 12-Pin Thin QFN (derate 16.7mW/C above +70C) ..1333mW 16-Pin Thin QFN (derate 20.8mW/C above +70C) ..1667mW Operating Temperature Range ...........................-40C to +85C Junction Temperature .............................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Soldering Temperature (reflow) .......................................+260C
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
(VBATT = 1.6V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1)
PARAMETER Operating Voltage Range (Note 2) Supply Current Startup Time (Note 3) MAX6782/MAX6783/MAX6784/MAX6785 0.5% hysteresis (A version) IN_ Falling Threshold (Note 4) IN_ Rising Threshold (Note 4) IN_, HADJ_ Input Leakage Current Reference Output Reference Load Regulation Reference Temperature Coefficient Reference Short-Circuit Current Hysteresis Adjustment Range Hysteresis Adjustment Logic Low Hysteresis Adjustment Logic High MAX6786/MAX6787/MAX6788 LBL_, LBH_ Threshold LBL_, LBH_ Input Leakage Current VTH VLBL, VLBH_ 0.3V 0.6024 0.6085 0.6146 5 V nA VHALL VHALH 0.17 0.4 TEMPCO VREF IREF = 0 to 1mA VINF VINR VIN_, VHADJ_ 0.3V 0.6024 0.6085 0.3 15 20 VREF 0.05 5% hysteresis (B version) 10% hysteresis (C version) 0.5994 0.5723 0.5422 0.6024 0.6055 0.5781 0.5477 0.6085 0.6115 0.5839 0.5531 0.6146 5 0.6146 V nA V mV/mA ppm/C mA V V V V SYMBOL VBATT IQ CONDITIONS TA = 0C to +70C TA = -40C to +85C VBATT = 3.7V, no load VBATT = 1.8V, no load VBATT rising from 0 to 1.6V MIN 1.05 1.2 6.3 5.7 5 TYP MAX 5.5 5.5 10 UNITS V A A ms
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages
ELECTRICAL CHARACTERISTICS (continued)
(VBATT = 1.6V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1)
PARAMETER MAX6782-MAX6788 LBO_ Propagation Delay LBO_ Output Low Voltage (PushPull or Open Drain) tPD VOL 100mV overdrive VBATT 1.2V, ISINK = 100A VBATT 2.7V, ISINK = 1.2mA VBATT 4.5V, ISINK = 3.2mA VBATT 1.6V, ISOURCE = 10A LBO_ Output High Voltage (Push-Pull) (Note 5) VOH VBATT 2.7V, ISOURCE = 500A VBATT 4.5V, ISOURCE = 800A LBO_ Output Leakage Current (Open Drain) MAX6789/MAX6790 IN_ Rising Threshold IN_ Hysteresis IN_ Input Leakage Current OV, OV Delay Time tPD VIN_ 0.3V 100mV overdrive VBATT 1.6V, ISINK = 100A, output asserted OV Output Low Voltage (PushPull or Open Drain) VOL VBATT 2.7V, ISINK = 1.2mA, output asserted VBATT 4.5V, ISINK = 3.2mA, output asserted VBATT 1.2V, ISOURCE = 10A, output not asserted OV Output High Voltage (PushPull) (Note 5) VOH VBATT 2.7V, ISOURCE = 500A, output not asserted VBATT 4.5V, ISINK = 800A, output not asserted OV Output Leakage Current (Open Drain) Output not asserted, VOV, VOV = 0 or 5V VBATT 1.2V, ISINK = 100A, output not asserted OV Output Low Voltage (Push-Pull or Open Drain) VOL VBATT 2.7V, ISINK = 1.2mA, output not asserted VBATT 4.5V, ISINK = 3.2mA, output not asserted 0.8 x VBATT 0.8 x VBATT 0.8 x VBATT 500 0.3 0.3 0.4 V nA V 30 0.3 0.3 0.4 V VTH+ 0.6024 0.6085 31 5 0.6146 V mV nA s Output not asserted, VLBO_ = 0 or 5V 0.8 x VBATT 0.8 x VBATT 0.8 x VBATT 500 30 0.3 0.3 0.4 s V V V V V V nA SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX6782-MAX6790
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages MAX6782-MAX6790
ELECTRICAL CHARACTERISTICS (continued)
(VBATT = 1.6V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1)
PARAMETER SYMBOL CONDITIONS VBATT 1.6V, ISOURCE = 10A, output asserted OV Output High Voltage (PushPull ) (Note 5) VOH VBATT 2.7V, ISOURCE = 500A, output asserted VBATT 4.5V, ISOURCE = 800A, output asserted OV Output Leakage Current (Open Drain) CLEAR Input Low Voltage CLEAR Input High Voltage CLEAR Pullup Resistance CLEAR Minimum Pulse Width CLEAR Delay Time tCLD VIL VIH 0.7 x VBATT 25 1 300 80 Output asserted, VOV = 0 or 5V MIN 0.8 x VBATT 0.8 x VBATT 0.8 x VBATT 500 0.3 x VBATT nA V V k s ns V TYP MAX UNITS
Note 1: Devices are tested at TA = +25C and guaranteed by design for TA = TMIN to TMAX as specified. Note 2: Operating voltage range ensures low battery output is in the correct state. Minimum battery voltage for electrical specification is 1.6V. Note 3: Reference and threshold accuracy is only guaranteed after the startup time. Startup time is guaranteed by design. Note 4: The rising threshold is guaranteed to be higher than the falling threshold. Note 5: The source current is the total source current from all outputs.
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages
Typical Operating Characteristics
(VBATT = 3.6V, TA = +25C, unless otherwise noted.)
MAX6782-MAX6790
SUPPLY CURRENT vs. TEMPERATURE
MAX6782 toc01
PROPAGATION DELAY vs. TEMPERATURE
MAX6782 toc02
MAXIMUM TRANSIENT DURATION vs. THRESHOLD OVERDRIVE
MAXIMUM TRANSIENT DURATION (s) 900 800 700 600 500 400 300 200 100 0 1 10 100 1000 OUTPUT ASSERTED ABOVE THIS LINE
MAX6782 toc03
8.0 VBATT = 5V 7.5 SUPPLY CURRENT (A) 7.0 6.5 6.0 5.5 5.0 4.5 4.0 -40 -15 10 35 60 VBATT = 1.8V VBATT = 3.6V
70 VIN_ = 100mV OVERDRIVE 60 PROPAGATION DELAY (s) 50 40 30 20 10 0
1000
85
-40
-15
10
35
60
85
TEMPERATURE (C)
TEMPERATURE (C)
THRESHOLD OVERDRIVE (mV)
NORMALIZED THRESHOLD VOLTAGES vs. TEMPERATURE (MAX6782TEA)
MAX6782 toc04
NORMALIZED THRESHOLD VOLTAGES vs. TEMPERATURE (MAX6782TEB)
MAX6782 toc05
NORMALIZED THRESHOLD VOLTAGES vs. TEMPERATURE (MAX6782TEC)
1.004 NORMALIZED THRESHOLD (V) 1.003 1.002 1.001 1.000 0.999 0.998 0.997 0.996 0.995 FALLING RISING NORMALIZED AT TA = +25C
MAX6782 toc06
1.005 1.004 NORMALIZED THRESHOLD (V) 1.003 1.002 1.001 1.000 0.999 0.998 0.997 0.996 0.995 -40 -15 10 35 60 RISING FALLING NORMALIZED AT TA = +25C
1.005 1.004 NORMALIZED THRESHOLD (V) 1.003 1.002 1.001 1.000 0.999 0.998 0.997 0.996 0.995 FALLING RISING NORMALIZED AT TA = +25C
1.005
85
-40
-15
10
35
60
85
-40
-15
10
35
60
85
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages MAX6782-MAX6790
Typical Operating Characteristics (continued)
(VBATT = 3.6V, TA = +25C, unless otherwise noted.)
LBO OUTPUT VOLTAGE LOW vs. SINK CURRENT
MAX6782 toc07
LBO OUTPUT VOLTAGE HIGH vs. SOURCE CURRENT
MAX6782 toc08
REFERENCE VOLTAGE vs. TEMPERATURE
MAX6782TEA REFERENCE VOLTAGE (V) 0.616
MAX6782 toc09
0.6 VBATT = 1.8V 0.5 OUTPUT VOLTAGE (V) 0.4 0.3 0.2 0.1 VBATT = 5.0V VBATT = 3.3V
5.5 5.0 4.5 OUTPUT VOLTAGE (V) 4.0 3.5 3.0 2.5 2.0 1.5 VBATT = 1.8V PUSH-PULL VERSIONS 0 1 2 3 4 5 VBATT = 3.3V VBATT = 5.0V
0.620
0.612
0.608
0.604
0 0 3 6 9 12 15 SINK CURRENT (mA)
1.0 SOURCE CURRENT (mA)
0.600 -40
-15
10
35
60
85
TEMPERATURE (C)
REFERENCE VOLTAGE vs. REFERENCE CURRENT
MAX6782 toc10
REFERENCE VOLTAGE vs. SUPPLY VOLTAGE
0.6094 REFERENCE VOLTAGE (V) 0.6093 0.6092 0.6091 0.6090 0.6089 0.6088 0.6087 0.6086 0.6085 MAX6782TEB
MAX6782 toc11
CLEAR LATCH CIRCUIT
MAX6782 toc12
0.65 0.64 0.63 0.62 VREF (V) 0.61 0.60 0.59 0.58 0.57 0.56 0.55 0
MAX6782TEB
0.6095
IN_ 5V/div
CLEAR 5V/div
OV 5V/div 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 100s/div
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 REFERENCE CURRENT (mA)
SUPPLY VOLTAGE (V)
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages
Pin Description
MAX6782/MAX6783/MAX6784/MAX6785
PIN MAX6782/ MAX6783 1 2 3 4 MAX6784/ MAX6785 1 2 -- 3 NAME FUNCTION Battery Monitor Input 2. Connect to an external resistive divider to set the trip threshold for monitor 2. Battery Monitor Input 3. Connect to an external resistive divider to set the trip threshold for monitor 3. Battery Monitor Input 4. Connect to an external resistive divider to set the trip threshold for monitor 4. Reference Output. REF can source up to 1mA. REF does not require an external bypass capacitor for stability. Keep the capacitance from REF to GND below 50pF. Hysteresis Adjustment Input 1. Connect HADJ1 to GND to select an internal preset hysteresis option. Connect a resistive divider from REF to HADJ1 and to GND to externally adjust the hysteresis for IN1 from its internal preset hysteresis (see Figure 6). Hysteresis Adjustment Input 2. Connect HADJ2 to GND to select an internal preset hysteresis option. Connect a resistive divider from REF to HADJ2 and to GND to externally adjust the hysteresis for IN2 from its internal preset hysteresis (see Figure 6). Hysteresis Adjustment Input 3. Connect HADJ3 to GND to select an internal preset hysteresis option. Connect a resistive divider from REF to HADJ3 and to GND to externally adjust the hysteresis for IN3 from its internal preset hysteresis (see Figure 6). Hysteresis Adjustment Input 4. Connect HADJ4 to GND to select an internal preset hysteresis option. Connect a resistive divider from REF to HADJ4 and to GND to externally adjust the hysteresis for IN4 from its internal preset hysteresis (see Figure 6). Active-Low, Low-Battery Output 4. LBO4 asserts when VIN4 falls below the falling threshold voltage. LBO4 deasserts when VIN4 exceeds the rising threshold voltage. Active-Low, Low-Battery Output 3. LBO3 asserts when VIN3 falls below the falling threshold voltage. LBO3 deasserts when VIN3 exceeds the rising threshold voltage. Active-Low, Low-Battery Output 2. LBO2 asserts when VIN2 falls below the falling threshold voltage. LBO2 deasserts when VIN2 exceeds the rising threshold voltage. Active-Low, Low-Battery Output 1. LBO1 asserts when VIN1 falls below the falling threshold voltage. LBO1 deasserts when VIN1 exceeds the rising threshold voltage. Battery Input. Power supply to the device. For better noise immunity, bypass BATT to GND with a 0.1F capacitor as close to the device as possible. Ground No Connection. Not internally connected. Battery Monitor Input 1. Connect to an external resistive divider to set the trip threshold for monitor 1. Exposed Pad. Connect EP to the ground plane. Do not use EP as the only ground connection.
MAX6782-MAX6790
IN2 IN3 IN4 REF
5
4
HADJ1
6
5
HADJ2
7
6
HADJ3
8
--
HADJ4
9 10 11 12 13 14 15 16 --
-- 7 8 9 10 11 -- 12 --
LBO4 LBO3 LBO2 LBO1 BATT GND N.C. IN1 EP
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages MAX6782-MAX6790
Pin Description (continued)
MAX6786/MAX6787/MAX6788
PIN 1 2 3 4 5 6 7 8 -- NAME LBL1 LBH1 LBL2 LBH2 GND LBO2 LBO1 BATT EP FUNCTION Falling Trip Level Input 1. Connect to an external resistive divider to set the falling trip level. Rising Trip Level Input 1. Connect to an external resistive divider to set the rising trip level. Falling Trip Level Input 2. Connect to an external resistive divider to set the falling trip level. Rising Trip Level Input 2. Connect to an external resistive divider to set the rising trip level. Ground Active-Low, Low-Battery Output 2. LBO2 asserts when VLBL2 falls below the falling threshold voltage. LBO2 deasserts when VLBH2 exceeds the rising threshold voltage. Active-Low, Low-Battery Output 1. LBO1 asserts when VLBL1 falls below the falling threshold voltage. LBO1 deasserts when VLBH1 exceeds the rising threshold voltage. Battery Input. Power supply to the device. For better noise immunity, bypass BATT to GND with a 0.1F capacitor as close to the device as possible. Exposed Pad. Connect EP to the ground plane. Do not use EP as the only ground connection.
MAX6789/MAX6790
PIN 1 2 3 4 5 6 7 8 9 10 -- NAME IN1 IN2 IN3 IN4 GND CLEAR N.C. OV OV BATT EP Overvoltage Monitor Input 1 Overvoltage Monitor Input 2 Overvoltage Monitor Input 3 Overvoltage Monitor Input 4 Ground Active-Low Clear Input. OV and OV do not latch when an overvoltage fault is detected if CLEAR is held low. CLEAR has an internal pullup resistor to BATT. No Connection. Not internally connected. Active-Low Overvoltage Output. When any of the inputs (VIN_) exceeds its respective rising threshold voltage, OV asserts and stays asserted until CLEAR is pulled low or the power to the device is cycled. OV does not latch when an overvoltage fault is detected if CLEAR is held low. Active-High Overvoltage Output. Inverse of OV. Battery Input. Power supply to the device. For better noise immunity, bypass BATT to GND with a 0.1F capacitor as close to the device as possible. Exposed Pad. Connect EP to the ground plane. Do not use EP as the only ground connection. FUNCTION
Detailed Description
The MAX6782-MAX6788 are designed to monitor two to four battery levels (1% accuracy) and assert an active-low output indicator when the monitored voltage level falls below the user-set threshold. Each battery level is associated with an independent open-drain or push-pull output. Each of these independent outputs can be used to provide low battery warnings at different voltage levels. Each of these monitored levels offers fixed or adjustable hysteresis in order to prevent the output from chattering as the battery recovers from the
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lighter loads. The MAX6782-MAX6785 also feature reference outputs that can source up to 1mA. The MAX6789/MAX6790 monitor four overvoltage conditions and assert the complementary overvoltage outputs when any voltage at the inputs exceeds its respective threshold. The MAX6789/MAX6790 allow each trip threshold to be set with external resistors. These devices also feature a latch and a clear function. Figures 1, 2, and 3 show the simplified block diagrams for the MAX6782-MAX6790. See the Selector Guide.
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages MAX6782-MAX6790
BATT REF IN1 REFERENCE COMPARATOR SECTION 1 HADJ1 LBO1 IN2 COMPARATOR SECTION 2 INTERNAL HYSTERESIS LADDER COMPARATOR SECTION 3 HADJ2 LBO2 IN3 HADJ3 LBO3 IN4 HYSTERESIS SELECT GND ( ) MAX6782/MAX6783 ONLY COMPARATOR SECTION 4 HADJ4 LBO4
MAX6782 MAX6783 MAX6784 MAX6785
Figure 1. MAX6782-MAX6785 Block Diagram
BATT
REF R1 LBL_
MAX6786 MAX6787 MAX6788
LBO_
RHYST LBH_
R2 GND
Figure 2. MAX6786/MAX6787/MAX6788 Block Diagram
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages MAX6782-MAX6790
BATT
IN_
MAX6789 MAX6790
REF LATCH CONTROL OV
CLEAR
GND
Figure 3. MAX6789/MAX6790 Block Diagram
Low-Battery/Overvoltage Output
All devices are offered with either push-pull or opendrain outputs (see the Selector Guide). The MAX6788 has one push-pull output and one open-drain output, configured as shown in Table 1.
Hysteresis
Input hysteresis defines two thresholds, separated by the hysteresis voltage, configured so the output asserts when the input falls below the falling threshold, and deasserts only when the input rises above the rising threshold. Figures 4 and 5 show this graphically. Hysteresis removes, or greatly reduces, the possibility of the output changing state in response to noise or battery-terminal voltage recovery after load removal.
Table 1. MAX6788 Outputs
DEVICE MAX6788 LBO1 Push-Pull LBO2 Open Drain
All open-drain outputs require an external pullup resistor. The open-drain pullup resistor may be connected to an external voltage up to +6V, regardless of the voltage at BATT.
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages MAX6782-MAX6790
VINR VINF
INTERNAL HYSTERESIS
IN_
VHALL VHADJ_ tPD tPD
LBO_
A) NORMAL OPERATION FOR VHADJ_ < VHALL.
VINR VINF
INTERNAL HYSTERESIS
IN_
VHADJ_ VHALH
tPD
tPD
LBO_
B) NORMAL OPERATION FOR VHADJ_ > VHALH.
Figure 4. MAX6782-MAX6785 Timing
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages MAX6782-MAX6790
VTH+ VTHIN_
CLEAR
OV tPD tCLD
OV
Figure 5. MAX6789/MAX6790 Timing
MAX6782-MAX6785 Hysteresis
Factory-Set Hysteresis The MAX6782-MAX6785 have factory-set hysteresis for ease of use and reduced external parts count. For these devices the absolute hysteresis voltage is a percentage of the internally generated reference. The amount depends on the device option. "A" devices have 0.5% hysteresis, "B" devices have 5% hysteresis, and "C" devices have 10% hysteresis. Table 2 presents the threshold voltages for devices with factory-set hysteresis. For factory-set hysteresis, connect HADJ_ to GND.
Externally Adjusted Hysteresis The MAX6782-MAX6785 can also be configured for externally adjustable hysteresis. Connect a resistive divider from REF to HADJ_ and to GND (Figure 6) to set the hysteresis voltage. The hysteresis adjustment range is from 0.4V to V REF , and the voltage at HADJ_ (V HADJ_ ) must be set higher than Hysteresis Adjustment Logic High (VHALH) (Figure 4b). Note that if VHADJ_ is lower than Hysteresis Adjustment Logic Low (VHALL), these devices switch back to the internal factory-set hysteresis (Figure 4a).
Table 2. Typical Falling and Rising Thresholds for MAX6782-MAX6785 (HADJ_ = GND)
DEVICE OPTION A B C PERCENT HYSTERESIS (%) 0.5 5 10 FALLING THRESHOLD (VINF) (V) 0.6055 0.5781 0.5477 RISING THRESHOLD (VINR) (V) 0.6085 0.6085 0.6085
MAX6786/MAX6787/MAX6788 Adjustable Hysteresis
The MAX6786/MAX6787/MAX6788 offer external hysteresis control through the resistive divider that monitors battery voltage. Figure 2 shows the connections for external hysteresis. See Calculating an External Hysteresis Resistive Divider (MAX6786/MAX6787/MAX6788) section for more information.
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages
Reference Output
The reference output can provide up to 1mA of output current. The output is not buffered. Excessive loading affects the accuracy of the thresholds. An external capacitor is not required for stability and is stable for capacitive loads up to 50pF. In applications where the load or the supply can experience step changes, a capacitor reduces the amount of overshoot (undershoot) and improves the circuit's transient response. Place the capacitor as close to the device as possible for best performance. old (VINF) on the associated IN_ (the rising threshold (VINR) is fixed). See Table 2. Calculate R3 using: e x VREF R3 = A IL where eA is the fraction of the maximum acceptable absolute resistive divider error attributable to the input leakage current (use 0.01 for 1%), VREF is the reference output voltage, and IL is the worst-case HADJ_ leakage current. Calculate R4 using: R4 = VINF x R3 VREF - VINF
MAX6782-MAX6790
Applications Information
Resistor-Value Selection
Choosing the proper external resistors is a balance between accuracy and power use. The input to the voltage monitor, while high impedance, draws a small current, and that current travels through the resistive divider, introducing error. If extremely high resistor values are used, this current introduces significant error. With extremely low resistor values, the error becomes negligible, but the resistive divider draws more power from the battery than necessary, and shortens battery life. See Figure 6 and calculate the optimum value for R1 using: e x VBATT R1 = A IL where eA is the fraction of the maximum acceptable absolute resistive divider error attributable to the input leakage current (use 0.01 for 1%), VBATT is the battery voltage at which LBO should activate, and IL is the worst-case IN_ leakage current, from the Electrical Characteristics. For example, for 0.5% error, a 2.8V battery minimum, and 5nA leakage, R 1 = 2.80M. Calculate R2 using: R2 = VINF x R1 VBATT - VINF
where VINF is the desired falling voltage threshold. To calculate the percent hysteresis, use:
-V V Hysteresis (%) = 100 x INR INF VINR
where VINR is the rising voltage.
Calculating an External Hysteresis Resistive Divider (MAX6786/MAX6787/MAX6788)
Setting the hysteresis externally requires calculating three resistor values, as indicated in Figure 2. First calculate R1 using: e x VBATT R1 = A IL and R20 using: R20 = VTH x R1 (as in the above example) VBATT - VTH
where R20 = R2 + RHYST determine the total resistivedivider current, ITOTAL, at the trip voltage using: ITOTAL = VBATT R1 + R20
where VINF is the falling threshold voltage from Table 2. Continuing the above example, and selecting VINF = 0.5477V (10% hysteresis device), R2 = 681k. There are other sources of error for the battery threshold, including resistor and input monitor tolerances.
Then, determine RHYST using: V RHYST = HYST ITOTAL where VHYST is the required hysteresis voltage. Finally, determine R2 using: R2 = R20 - RHYST
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Calculating an External Hysteresis Resistive Divider (MAX6782-MAX6785)
To set the hysteresis, place a resistive divider from REF to HADJ_ as shown in Figure 6. The resistive divider sets voltage on HADJ_, which controls the falling thresh-
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages MAX6782-MAX6790
Monitoring a Battery Voltage Higher than the Allowable VBATT
For monitoring higher voltages, supply a voltage to BATT, which is within the specified supply range, and power the input resistive divider from the high voltage to be monitored. Do not exceed the Absolute Maximum Ratings.
Adding External Capacitance to Reduce Noise and Transients
If monitoring voltages in a noisy environment, add a bypass capacitor of 0.1F from BATT to GND as close as possible to the device. For systems with large transients, additional capacitance may be required.
Maintaining Reference Accuracy
Since the ground connection of the MAX6782-MAX6790 has a small series resistance, any current flowing into an output flows to ground and causes a small voltage to develop from the internal ground to GND. This has the effect of slightly increasing the reference voltage. To minimize the effect on the reference voltage, keep the total output sink current below 3mA.
Reverse-Battery Protection
To prevent damage to the device during a reverse-battery condition, connect the MAX6782-MAX6785 in the configuration shown in Figure 6a or 6b. For the internal reversebattery protection to function correctly on the MAX6782- MAX6790, several conditions must be satisfied: * The connections to IN_/LBL_/LBH_ must be made to the center node of a resistive divider going from BATT to GND. The Thevenin equivalent impedance of the resistive divider must not fall below 1k in order to limit the current. * HADJ_ (MAX6782-MAX6785 only) must either be connected to GND or to the center node of a resistive divider going from REF to GND. * The outputs may only be connected to devices powered by the same battery as the MAX6782- MAX6790. Note that the MAX6782-MAX6790 will not protect other devices in the circuit.
R1 IN_ R2 REF
BATT LBO_
MAX6782 MAX6783 MAX6784 MAX6785
HADJ_
Additional Application Circuit
GND
Figure 7 shows the MAX6786/MAX6787/MAX6788 in a typical two-battery-level monitoring circuit.
A) FACTORY PRESET HYSTERESIS CONNECTION
BATT LBL1
1
R1 IN_ R2 R3 HADJ_ R4
BATT LBO_
LBH1
LBO1
REF
MAX6782 MAX6783 MAX6784 MAX6785
MAX6786 MAX6787 MAX6788
LBL2 LBO2 LBH2
GND
GND
B) EXTERNAL HYSTERESIS ADJUST CONNECTION
Figure 6. Internal Preset or Externally Adjusted Hysteresis Connection
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Figure 7. Two-Battery-Level Monitor Configuration
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages
Typical Operating Circuit
MAX6782-MAX6790
BATT IN1 LBO1 DEAD BATTERY
IN2
LBO2
BACKUP MEMORY
MAX6782 MAX6783
IN3
LBO3
SHUT DOWN SUBSYSTEM
IN4
LBO4
SLOW DOWN PROCESSOR SPEED
REF HADJ_ GND
Top Marks
PART MAX6782TEA+ MAX6782TEB+ MAX6782TEC+ MAX6783TEA+ MAX6783TEB+ MAX6783TEC+ MAX6784TCA+ MAX6784TCB+ MAX6784TCC+ MAX6785TCA+ MAX6785TCB+ MAX6785TCC+ MAX6786TA+ MAX6787TA+ MAX6788TA+ MAX6789TB+ MAX6790TB+ TOP MARK +AEG +AEH +AEI +AEJ +AEK +AEL +AAV +AAW +AAX +AAY +AAZ +ABA +APU +APV +APW +AQI +AQJ
Ordering Information (continued)
PART MAX6786TA+T MAX6787TA+T MAX6788TA+T MAX6789TB+T MAX6790TB+T TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 8 TDFN-EP* 8 TDFN-EP* 8 TDFN-EP* 10 TDFN-EP* 10 TDFN-EP*
+Denotes a lead-free/RoHS-compliant package. *EP = Exposed pad. The MAX6782/MAX6783/MAX6784/MAX6785 are available with factory-trimmed hysteresis. Specify trim by replacing "_" with "A" for 0.5%, "B" for 5%, or "C" for 10% hysteresis.
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Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages MAX6782-MAX6790
Pin Configurations
LBO1 LBO2 LBO1 LBO2 LBO3 LBO4 LBO3 7
TOP VIEW
12
11
10
9
9
8
BATT 13 GND 14 N.C. 15 IN1 16
8 7
HADJ4 HADJ3
BATT 10
6
HADJ3
MAX6782 MAX6783 +
1 IN2 2 IN3 3 IN4 EP
GND 11 6 5 HADJ2 HADJ1 IN1 12
MAX6784 MAX6785 +
EP
5
HADJ2
HADJ1
4 REF
1 IN2
2 IN3
3 REF 8 7 EP 3 IN3 4 IN4 GND CLEAR 6 5 N.C.
THIN QFN
THIN QFN
BATT
LBO2
LBO1
BATT
GND
OV 9 2 IN2
8
7
6
5
10
MAX6786 MAX6787 MAX6788 +
1 LBL1 2 LBH1 3 LBL2 EP 4 LBH2
MAX6789 MAX6790 +
1 IN1
TDFN
TDFN
Chip Information
PROCESS: BiCMOS
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 8 TDFN-EP 10 TDFN-EP 12 TQFN-EP 16 TQFN-EP PACKAGE CODE T833-3 T1033-1 T1233-1 T1633-4 DOCUMENT NO. 21-0137 21-0137 21-0136 21-0136
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OV
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level Battery Monitors in Small TDFN and TQFN Packages
Revision History
REVISION NUMBER 0 1 2 3 REVISION DATE 8/06 10/06 5/08 3/10 Initial release Released the MAX6784, MAX6786-MAX6790. Updated the Pin Description tables. Updated the Absolute Maximum Ratings and the Electrical Characteristics table. DESCRIPTION PAGES CHANGED -- 1, 15 7, 8 2
MAX6782-MAX6790
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 ____________________ 17
(c) 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.

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