MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
________________________________________________________________
Maxim Integrated Products
1
19-0541; Rev 3; 3/10
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.
General Description Features
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 alka-
line/NiCd/NiMH power sources. These devices feature
fixed and adjustable hysteresis options to eliminate out-
put 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 fea-
ture quad-level overvoltage detectors with complemen-
tary 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 space-
saving TDFN and TQFN packages and is fully specified
over the -40°C to +85°C extended temperature range.
Ordering Information
Selector Guide
Applications
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.
PART TEMP RANGE PIN-PACKAGE
MAX6782TE_+ -40°C to +85°C 16 TQFN-EP*
MAX6783TE_+ -40°C to +85°C 16 TQFN-EP*
MAX6784TC_+ -40°C to +85°C 12 TQFN-EP*
MAX6785TC_+ -40°C to +85°C 12 TQFN-EP*
PART MONITOR LEVEL LBO OUTPUT OV OV OUTPUT TYPE HYSTERESIS
MAX6782TE_+ 4 Quad — — Push-Pull Fixed/Adj
MAX6783TE_+ 4 Quad — — Open Drain Fixed/Adj
MAX6784TC_+ 3 Triple — — Push-Pull Fixed/Adj
MAX6785TC_+ 3 Triple — — Open Drain Fixed/Adj
MAX6786TA+ 2 Dual — — Push-Pull Adj
MAX6787TA+ 2 Dual — — Open Drain Adj
MAX6788TA+ 2 Dual — — Push-Pull/Open Drain Adj
MAX6789TB+ 4 — Single Single Push-Pull —
MAX6790TB+ 4 — Single Single Open Drain —
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.
Battery-Powered Systems
(Single-Cell Li+ or
Multicell NiMH, NiCd,
Alkaline)
Cell Phones/Cordless
Phones
Pagers
Portable Medical Devices
PDAs
Electronic Toys
MP3 Players
o1% Accurate Threshold Specified Over Full
Temperature Range
oDual-/Triple-/Quad, Low-Battery Output Options
oLow 5.7µA Battery Current
oOpen-Drain or Push-Pull Outputs
oFixed or Adjustable Hysteresis
oLow Input Bias Current
oGuaranteed Valid Low-Battery-Output Logic State
Down to VBATT = 1.05V
oReverse-Battery Protection
oImmune to Short Battery Transients
oFully Specified from -40°C to +85°C
oSmall TDFN and TQFN Packages
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VBATT = 1.6V to 5.5V, TA = -40°C to +85°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 1)
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.
(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= +70°C)
8-Pin TDFN (derate 23.8mW/°C above +70°C) ..........1905mW
10-Pin TDFN (derate 24.4mW/°C above +70°C) ........1951mW
12-Pin Thin QFN (derate 16.7mW/°C above +70°C) ..1333mW
16-Pin Thin QFN (derate 20.8mW/°C above +70°C) ..1667mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ………………………………………+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
TA = 0°C to +70°C 1.05 5.5
Operating Voltage Range
(Note 2) VBATT TA = -40°C to +85°C 1.2 5.5 V
VBATT = 3.7V, no load 6.3 10 µA
Supply Current IQVBATT = 1.8V, no load 5.7 µA
Startup Time (Note 3) VBATT rising from 0 to 1.6V 5 ms
MAX6782/MAX6783/MAX6784/MAX6785
0.5% hysteresis (A version) 0.5994 0.6055 0.6115
5% hysteresis (B version) 0.5723 0.5781 0.5839
IN_ Falling Threshold (Note 4) VINF
10% hysteresis (C version) 0.5422 0.5477 0.5531
V
IN_ Rising Threshold (Note 4) VINR 0.6024 0.6085 0.6146 V
IN_, HADJ_ Input Leakage
Current VIN_, VHADJ_ ≥ 0.3V 5nA
Reference Output VREF 0.6024 0.6085 0.6146 V
Reference Load Regulation IREF = 0 to 1mA 0.3 mV/mA
Reference Temperature
Coefficient TEMPCO 15 ppm/°C
Reference Short-Circuit Current 20 mA
Hysteresis Adjustment Range 0.4 VREF V
Hysteresis Adjustment Logic Low VHALL 0.05 V
Hysteresis Adjustment Logic
High VHALH 0.17 V
MAX6786/MAX6787/MAX6788
LBL_, LBH_ Threshold VTH 0.6024 0.6085 0.6146 V
LBL_, LBH_ Input Leakage
Current VLBL, VLBH_ ≥ 0.3V 5nA
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VBATT = 1.6V to 5.5V, TA = -40°C to +85°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX6782–MAX6788
LBO_ Propagation Delay tPD ±100mV overdrive 30 µs
VBATT ≥ 1.2V, ISINK = 100µA 0.3 V
VBATT ≥ 2.7V, ISINK = 1.2mA 0.3 V
LBO_ Output Low Voltage (Push-
Pull or Open Drain) VOL
VBATT ≥ 4.5V, ISINK = 3.2mA 0.4 V
VBATT ≥ 1.6V, ISOURCE = 10µA 0.8 x
VBATT V
VBATT ≥ 2.7V, ISOURCE = 500µA 0.8 x
VBATT V
LBO_ Output High Voltage
(Push-Pull) (Note 5) VOH
VBATT ≥ 4.5V, ISOURCE = 800µA 0.8 x
VBATT V
LBO_ Output Leakage Current
(Open Drain) Output not asserted, VLBO_ = 0 or 5V 500 nA
MAX6789/MAX6790
IN_ Rising Threshold VTH+ 0.6024 0.6085 0.6146 V
IN_ Hysteresis 31 mV
IN_ Input Leakage Current VIN_ ≥ 0.3V 5nA
OV, OV Delay Time tPD ±100mV overdrive 30 µs
VBATT ≥ 1.6V, ISINK = 100µA, output
asserted 0.3
VBATT ≥ 2.7V, ISINK = 1.2mA, output
asserted 0.3
OV Output Low Voltage (Push-
Pull or Open Drain) VOL
VBATT ≥ 4.5V, ISINK = 3.2mA, output
asserted 0.4
V
VBATT ≥ 1.2V, ISOURCE = 10µA, output not
asserted
0.8 x
VBATT
VBATT ≥ 2.7V, ISOURCE = 500µA, output not
asserted
0.8 x
VBATT
OV Output High Voltage (Push-
Pull) (Note 5) VOH
VBATT ≥ 4.5V, ISINK = 800µA, output not
asserted
0.8 x
VBATT
V
OV Output Leakage Current
(Open Drain) Output not asserted, VOV, VOV = 0 or 5V 500 nA
VBATT ≥ 1.2V, ISINK = 100µA, output not
asserted 0.3
VBATT ≥ 2.7V, ISINK = 1.2mA, output not
asserted 0.3
OV Output Low Voltage
(Push-Pull or Open Drain) VOL
VBATT ≥ 4.5V, ISINK = 3.2mA, output not
asserted 0.4
V
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (continued)
(VBATT = 1.6V to 5.5V, TA = -40°C to +85°C, unless otherwise specified. Typical values are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
VBATT ≥ 1.6V, ISOURCE = 10µA, output
asserted
0.8 x
VBATT
VBATT ≥ 2.7V, ISOURCE = 500µA, output
asserted
0.8 x
VBATT
OV Output High Voltage (Push-
Pull ) (Note 5) VOH
VBATT ≥ 4.5V, ISOURCE = 800µA, output
asserted
0.8 x
VBATT
V
OV Output Leakage Current
(Open Drain) Output asserted, VOV = 0 or 5V 500 nA
CLEAR Input Low Voltage VIL 0.3 x
VBATT V
CLEAR Input High Voltage VIH 0.7 x
VBATT V
CLEAR Pullup Resistance 25 80 kΩ
CLEAR Minimum Pulse Width 1 µs
CLEAR Delay Time tCLD 300 ns
Note 1: Devices are tested at TA = +25°C 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 specifica-
tion 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.
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
_______________________________________________________________________________________
5
SUPPLY CURRENT
vs. TEMPERATURE
MAX6782 toc01
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
6035-15 10
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
4.0
-40 85
VBATT = 5V
VBATT = 3.6V
VBATT = 1.8V
PROPAGATION DELAY
vs. TEMPERATURE
MAX6782 toc02
TEMPERATURE (°C)
PROPAGATION DELAY (µs)
603510-15
10
20
30
40
50
60
70
0
-40 85
VIN_ = ±100mV OVERDRIVE
MAXIMUM TRANSIENT DURATION
vs. THRESHOLD OVERDRIVE
MAX6782 toc03
THRESHOLD OVERDRIVE (mV)
MAXIMUM TRANSIENT DURATION (µs)
10010
100
200
300
400
500
600
700
800
900
1000
0
1 1000
OUTPUT ASSERTED ABOVE THIS LINE
NORMALIZED THRESHOLD VOLTAGES
vs. TEMPERATURE (MAX6782TEA)
MAX6782 toc04
TEMPERATURE (°C)
NORMALIZED THRESHOLD (V)
603510-15
0.996
0.997
0.998
0.999
1.000
1.001
1.002
1.003
1.004
1.005
0.995
-40 85
NORMALIZED AT TA = +25°C
FALLING
RISING
NORMALIZED THRESHOLD VOLTAGES
vs. TEMPERATURE (MAX6782TEB)
MAX6782 toc05
TEMPERATURE (°C)
NORMALIZED THRESHOLD (V)
603510-15
0.996
0.997
0.998
0.999
1.000
1.001
1.002
1.003
1.004
1.005
0.995
-40 85
NORMALIZED AT TA = +25°C
FALLING
RISING
NORMALIZED THRESHOLD VOLTAGES
vs. TEMPERATURE (MAX6782TEC)
MAX6782 toc06
TEMPERATURE (°C)
NORMALIZED THRESHOLD (V)
603510-15
0.996
0.997
0.998
0.999
1.000
1.001
1.002
1.003
1.004
1.005
0.995
-40 85
NORMALIZED AT TA = +25°C
FALLING
RISING
Typical Operating Characteristics
(VBATT = 3.6V, TA= +25°C, unless otherwise noted.)
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VBATT = 3.6V, TA= +25°C, unless otherwise noted.)
LBO OUTPUT VOLTAGE LOW
vs. SINK CURRENT
MAX6782 toc07
SINK CURRENT (mA)
OUTPUT VOLTAGE (V)
12963
0.1
0.2
0.3
0.4
0.5
0.6
0
015
VBATT = 1.8V VBATT = 3.3V
VBATT = 5.0V
MAX6782 toc08
SOURCE CURRENT (mA)
OUTPUT VOLTAGE (V)
4321
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
1.0
05
LBO OUTPUT VOLTAGE HIGH
vs. SOURCE CURRENT
VBATT = 1.8V
VBATT = 3.3V
VBATT = 5.0V
PUSH-PULL
VERSIONS
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX6782 toc09
TEMPERATURE (°C)
REFERENCE VOLTAGE (V)
603510-15
0.604
0.608
0.612
0.616
0.620
0.600
-40 85
MAX6782TEA
REFERENCE VOLTAGE
vs. REFERENCE CURRENT
MAX6782 toc10
REFERENCE CURRENT (mA)
VREF (V)
0.90.80.6 0.70.2 0.3 0.4 0.50.1
0.56
0.57
0.58
0.59
0.60
0.61
0.62
0.63
0.64
0.65
0.55
0 1.0
MAX6782TEB
REFERENCE VOLTAGE
vs. SUPPLY VOLTAGE
MAX6782 toc11
SUPPLY VOLTAGE (V)
REFERENCE VOLTAGE (V)
5.04.53.5 4.02.5 3.02.0
0.6086
0.6087
0.6088
0.6089
0.6090
0.6091
0.6092
0.6093
0.6094
0.6095
0.6085
1.5 5.5
MAX6782TEB
CLEAR LATCH CIRCUIT
MAX6782 toc12
100µs/div
IN_
5V/div
CLEAR
5V/div
OV
5V/div
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
_______________________________________________________________________________________ 7
Pin Description
PIN
MAX6782/
MAX6783
MAX6784/
MAX6785
NAME FUNCTION
1 1 IN2 Battery Monitor Input 2. Connect to an external resistive divider to set the trip
threshold for monitor 2.
2 2 IN3 Battery Monitor Input 3. Connect to an external resistive divider to set the trip
threshold for monitor 3.
3 — IN4 Battery Monitor Input 4. Connect to an external resistive divider to set the trip
threshold for monitor 4.
4 3 REF 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.
5 4 HADJ1
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).
6 5 HADJ2
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).
7 6 HADJ3
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).
8 — HADJ4
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).
9—LBO4 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.
10 7 LBO3 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.
11 8 LBO2 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.
12 9 LBO1 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.
13 10 BATT Battery Input. Power supply to the device. For better noise immunity, bypass BATT
to GND with a 0.1µF capacitor as close to the device as possible.
14 11 GND Ground
15 — N.C. No Connection. Not internally connected.
16 12 IN1 Battery Monitor Input 1. Connect to an external resistive divider to set the trip
threshold for monitor 1.
——EP
Exposed Pad. Connect EP to the ground plane. Do not use EP as the only ground
connection.
MAX6782/MAX6783/MAX6784/MAX6785
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
8 _______________________________________________________________________________________
Pin Description (continued)
PIN NAME FUNCTION
1 LBL1 Falling Trip Level Input 1. Connect to an external resistive divider to set the falling trip level.
2 LBH1 Rising Trip Level Input 1. Connect to an external resistive divider to set the rising trip level.
3 LBL2 Falling Trip Level Input 2. Connect to an external resistive divider to set the falling trip level.
4 LBH2 Rising Trip Level Input 2. Connect to an external resistive divider to set the rising trip level.
5 GND Ground
6LBO2 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.
7LBO1 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.
8 BATT Battery Input. Power supply to the device. For better noise immunity, bypass BATT to GND with a 0.1µF
capacitor as close to the device as possible.
— EP Exposed Pad. Connect EP to the ground plane. Do not use EP as the only ground connection.
MAX6786/MAX6787/MAX6788
PIN NAME FUNCTION
1 IN1 Overvoltage Monitor Input 1
2 IN2 Overvoltage Monitor Input 2
3 IN3 Overvoltage Monitor Input 3
4 IN4 Overvoltage Monitor Input 4
5 GND Ground
6CLEAR 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.
7 N.C. No Connection. Not internally connected.
8OV
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.
9 OV Active-High Overvoltage Output. Inverse of OV.
10 BATT Battery Input. Power supply to the device. For better noise immunity, bypass BATT to GND with a 0.1µF
capacitor as close to the device as possible.
— EP Exposed Pad. Connect EP to the ground plane. Do not use EP as the only ground connection.
MAX6789/MAX6790
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 differ-
ent 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
lighter loads. The MAX6782–MAX6785 also feature ref-
erence outputs that can source up to 1mA.
The MAX6789/MAX6790 monitor four overvoltage con-
ditions and assert the complementary overvoltage out-
puts 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
.
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
_______________________________________________________________________________________ 9
MAX6782
MAX6783
MAX6784
MAX6785 HYSTERESIS
SELECT
GND
( ) MAX6782/MAX6783 ONLY
COMPARATOR
SECTION 1
REF
COMPARATOR
SECTION 2
COMPARATOR
SECTION 3
COMPARATOR
SECTION 4
REFERENCE
INTERNAL
HYSTERESIS
LADDER
BATT
IN1
HADJ1
LBO1
IN2
HADJ2
LBO2
IN3
HADJ3
LBO3
IN4
HADJ4
LBO4
Figure 1. MAX6782–MAX6785 Block Diagram
MAX6786
MAX6787
MAX6788
REF
BATT
R1
RHYST
LBH_
LBL_
LBO_
R2
GND
Figure 2. MAX6786/MAX6787/MAX6788 Block Diagram
MAX6782–MAX6790
Low-Battery/Overvoltage Output
All devices are offered with either push-pull or open-
drain outputs (see the
Selector Guide
). The MAX6788
has one push-pull output and one open-drain output,
configured as shown in Table 1.
All open-drain outputs require an external pullup resis-
tor. The open-drain pullup resistor may be connected
to an external voltage up to +6V, regardless of the volt-
age at BATT.
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.
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
10 ______________________________________________________________________________________
MAX6789
MAX6790
REF
BATT
IN_
CLEAR
OV
GND
LATCH
CONTROL
Figure 3. MAX6789/MAX6790 Block Diagram
DEVICE LBO1 LBO2
MAX6788 Push-Pull Open Drain
Table 1. MAX6788 Outputs
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
______________________________________________________________________________________ 11
INTERNAL HYSTERESIS
INTERNAL HYSTERESIS
VINR
VINF
IN_
LBO_
VHALL
VINR
VINF
VHADJ_
VHALH
tPD tPD
tPD tPD
VHADJ_
A) NORMAL OPERATION FOR VHADJ_ < VHALL.
B) NORMAL OPERATION FOR VHADJ_ > VHALH.
LBO_
IN_
Figure 4. MAX6782–MAX6785 Timing
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
12 ______________________________________________________________________________________
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 per-
centage 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 hys-
teresis. 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 VREF, and the voltage at HADJ_
(VHADJ_) 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 fac-
tory-set hysteresis (Figure 4a).
MAX6786/MAX6787/MAX6788 Adjustable
Hysteresis
The MAX6786/MAX6787/MAX6788 offer external hystere-
sis control through the resistive divider that monitors bat-
tery voltage. Figure 2 shows the connections for external
hysteresis. See
Calculating an External Hysteresis
Resistive Divider
(MAX6786/MAX6787/MAX6788) section
for more information.
tPD
VTH+
VTH-
IN_
CLEAR
OV
OV
tCLD
Figure 5. MAX6789/MAX6790 Timing
DEVICE
OPTION
PERCENT
HYSTERESIS
(%)
FALLING
THRESHOLD
(VINF) (V)
RISING
THRESHOLD
(VINR) (V)
A 0.5 0.6055 0.6085
B 5 0.5781 0.6085
C 10 0.5477 0.6085
Table 2. Typical Falling and Rising
Thresholds for MAX6782–MAX6785
(HADJ_ = GND)
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 (under-
shoot) and improves the circuit’s transient response.
Place the capacitor as close to the device as possible
for best performance.
Applications Information
Resistor-Value Selection
Choosing the proper external resistors is a balance
between accuracy and power use. The input to the volt-
age monitor, while high impedance, draws a small cur-
rent, and that current travels through the resistive
divider, introducing error. If extremely high resistor val-
ues 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:
where eAis 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 ILis the
worst-case IN_ leakage current, from the
Electrical
Characteristics
. For example, for 0.5% error, a 2.8V
battery minimum, and 5nA leakage, R1= 2.80MΩ.
Calculate R2using:
where VINF is the falling threshold voltage from Table 2.
Continuing the above example, and selecting VINF =
0.5477V (10% hysteresis device), R2= 681kΩ. There
are other sources of error for the battery threshold,
including resistor and input monitor tolerances.
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-
old (VINF) on the associated IN_ (the rising threshold
(VINR) is fixed). See Table 2. Calculate R3using:
where eAis the fraction of the maximum acceptable
absolute resistive divider error attributable to the input
leakage current (use 0.01 for 1%), VREF is the refer-
ence output voltage, and ILis the worst-case HADJ_
leakage current. Calculate R4using:
where VINF is the desired falling voltage threshold. To
calculate the percent hysteresis, use:
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 cal-
culate R1using:
and R20 using:
where R20 = R2+ RHYST determine the total resistive-
divider current, ITOTAL, at the trip voltage using:
Then, determine RHYST using:
where VHYST is the required hysteresis voltage.
Finally, determine R2using:
R2= R20 - RHYST
RV
I
HYST HYST
TOTAL
=
IV
RR
TOTAL BATT
=+
120
RVR
VV
as in the above example
TH
BATT TH
20 1
=×
−
( )
ReV
I
A BATT
L
1=×
Hysteresis VV
V
INR INF
INR
%
()
=× −
100
ReV
I
A REF
L
3=×
RVR
VV
INF
BATT INF
21
=×
−
ReV
I
A BATT
L
1=×
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
______________________________________________________________________________________ 13
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 moni-
tored. Do not exceed the Absolute Maximum Ratings.
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 mini-
mize the effect on the reference voltage, keep the total
output sink current below 3mA.
Adding External Capacitance to Reduce
Noise and Transients
If monitoring voltages in a noisy environment, add a
bypass capacitor of 0.1µF from BATT to GND as close
as possible to the device. For systems with large tran-
sients, additional capacitance may be required.
Reverse-Battery Protection
To prevent damage to the device during a reverse-battery
condition, connect the MAX6782–MAX6785 in the configu-
ration shown in Figure 6a or 6b. For the internal reverse-
battery 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 1kΩin
order to limit the current.
• HADJ_ (MAX6782–MAX6785 only) must either be
connected to GND or to the center node of a resis-
tive divider going from REF to GND.
• The outputs may only be connected to devices pow-
ered by the same battery as the MAX6782–
MAX6790.
Note that the MAX6782–MAX6790 will not protect other
devices in the circuit.
Additional Application Circuit
Figure 7 shows the MAX6786/MAX6787/MAX6788 in a
typical two-battery-level monitoring circuit.
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
14 ______________________________________________________________________________________
MAX6782
MAX6783
MAX6784
MAX6785
IN_
R1
R2
R1
R2
A) FACTORY PRESET HYSTERESIS CONNECTION
LBO_
REF
HADJ_
GND
BATT
MAX6782
MAX6783
MAX6784
MAX6785
IN_
B) EXTERNAL HYSTERESIS ADJUST CONNECTION
LBO_
REF
HADJ_
GND
BATT
R3
R4
1
Figure 6. Internal Preset or Externally Adjusted Hysteresis
Connection
MAX6786
MAX6787
MAX6788
LBL1
LBO1
LBH1
LBL2
LBH2
GND
BATT
LBO2
Figure 7. Two-Battery-Level Monitor Configuration
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
______________________________________________________________________________________ 15
Top Marks
PART TOP MARK
MAX6782TEA+ +AEG
MAX6782TEB+ +AEH
MAX6782TEC+ +AEI
MAX6783TEA+ +AEJ
MAX6783TEB+ +AEK
MAX6783TEC+ +AEL
MAX6784TCA+ +AAV
MAX6784TCB+ +AAW
MAX6784TCC+ +AAX
MAX6785TCA+ +AAY
MAX6785TCB+ +AAZ
MAX6785TCC+ +ABA
MAX6786TA+ +APU
MAX6787TA+ +APV
MAX6788TA+ +APW
MAX6789TB+ +AQI
MAX6790TB+ +AQJ
Typical Operating Circuit
MAX6782
MAX6783
IN1 LBO1 DEAD BATTERY
BACKUP MEMORY
SHUT DOWN
SUBSYSTEM
SLOW DOWN
PROCESSOR SPEED
IN2
IN3
IN4
GNDHADJ_
BATT
LBO2
LBO3
LBO4
REF
Ordering Information (continued)
+
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.
PART TEMP RANGE PIN-PACKAGE
MAX6786TA+T -40°C to +85°C 8 TDFN-EP*
MAX6787TA+T -40°C to +85°C 8 TDFN-EP*
MAX6788TA+T -40°C to +85°C 8 TDFN-EP*
MAX6789TB+T -40°C to +85°C 10 TDFN-EP*
MAX6790TB+T -40°C to +85°C 10 TDFN-EP*
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
16 ______________________________________________________________________________________
Pin Configurations
15
16 +
++
+
14
13
6
5
7
IN3
REF
8
IN2
LBO2
LBO4
LBO1
12
GND
4
12 11 9
N.C.
IN1
HADJ4
HADJ3
HADJ2
HADJ1
MAX6782
MAX6783
IN4 LBO3
3
10
BATT
THIN QFN
TOP VIEW
12
11
10
EP
EP
EP
EP
5
IN3
REF
6
IN2
LBO2
LBO3
LBO1
12
GND
3
987
IN1
HADJ3
HADJ2
HADJ1
MAX6784
MAX6785
BATT
THIN QFN
134
865
BATT
LBO2
GND
MAX6786
MAX6787
MAX6788
2
7
LBO1
LBL1
LBL2
LBH2
LBH1
TDFN
134
10 87
BATT
OV
N.C.
IN1
IN3
IN4
MAX6789
MAX6790
2
9
OVIN2
5
6
CLEARGND
TDFN
Chip Information
PROCESS: BiCMOS
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
8 TDFN-EP T833-3 21-0137
10 TDFN-EP T1033-1 21-0137
12 TQFN-EP T1233-1 21-0136
16 TQFN-EP T1633-4 21-0136
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 draw-
ings may show a different suffix character, but the drawing per-
tains to the package regardless of RoHS status.
MAX6782–MAX6790
Low-Power, 1% Accurate, Dual-/Triple-/Quad-Level
Battery Monitors in Small TDFN and TQFN Packages
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
© 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 8/06 Initial release —
1 10/06 Released the MAX6784, MAX6786–MAX6790. 1, 15
2 5/08 Updated the Pin Description tables. 7, 8
3 3/10 Updated the Absolute Maximum Ratings and the Electrical Characteristics
table. 2