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19-2535; Rev 0; 7/02
Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset
General Description
The MAX6439-MAX6442 are a family of ultra-low-power battery monitors with integrated microprocessor (P) supervisors. The battery monitors are offered with single or dual low-battery output options that can be used to signal when the battery is OK (enabling full system operation), when the battery is low (for low-power system operation), and when the battery is dead (to disable system operation). These devices also have an independent P supervisor that monitors VCC and provides an active-low reset output. A manual reset function is available to reset the P with a push-button. No external components are required. The MAX6439-MAX6442 are offered with several factory-trimmed low-battery threshold combinations ideal for single-cell lithium-ion (Li+) or multicell alkaline/NiCd/ NiMH applications. When the battery voltage drops below each specified low threshold, the low-battery outputs are asserted to alert the system. When the voltage rises above the specified high thresholds, the outputs are deasserted after a 150ms minimum timeout period, ensuring the voltages have stabilized before power circuitry is activated or providing microprocessor reset timing. The low and high thresholds provide hysteresis in battery-operated systems to eliminate output chattering. The MAX6439/MAX6440 offer factory-trimmed battery monitors with a single output. The MAX6441/MAX6442 offer factory-trimmed battery monitors with dual outputs. All battery monitors have open-drain low-battery outputs. The MAX6439-MAX6442 monitor system voltages (VCC) from 1.8V to 3.3V with seven fixed reset threshold options. Each device is offered with two minimum reset timeout periods of 150ms or 1200ms. The MAX6439/ MAX6441 are offered with an open-drain RESET output and the MAX6440/MAX6442 are offered with a pushpull RESET output. The MAX6439-MAX6442 are offered in a SOT23 package and are fully specified over a -40C to +85C temperature range.
Features
o Factory-Trimmed VBATT Threshold Options for Monitoring Single-Cell Li+ or Multicell Alkaline/NiCd/NiMH Applications o Immune to Short Battery Voltage Transients o Low Current (2.5A typ at 3.6V) o Single and Dual Low-Battery Output Options o 150ms Minimum LBO Timeout Period o Independent P Reset with Manual Reset o Factory-Set Reset Thresholds for Monitoring VCC from 1.8V to 3.3V o Available with 150ms (min) and 1.2s (min) VCC Reset Timeout Period Options o -40C to +85C Operating Temperature Range o Small 6- and 8-Pin SOT23 Packages o No External Components
MAX6439-MAX6442
Ordering Information
PART MAX6439UT_ _ _D_-T MAX6440UT_ _ _D_-T MAX6441KA_ _ _D_-T MAX6442KA_ _ _D_-T TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 6 SOT23-6 6 SOT23-6 8 SOT23-8 8 SOT23-8
Note: The first two "_ _" are placeholders for the battery monitor voltage levels. Desired threshold levels are set by the part number suffix found in Tables 1 and 2. The third "_" is the VCC reset threshold level suffix found in Table 3. The "_" after the D is a placeholder for the reset timeout period suffix found in Table 4. All devices are available in tape-and-reel only. There is a 2500-piece minimum order increment for standard versions. Sample stock is typically held on standard versions only. Nonstandard versions require a minimum order increment of 10,000 pieces. Contact factory for availability.
Applications
Battery-Powered Systems (Single-Cell Li+ or Two-/Three-Cell NiMH, NiCd, Alkaline) Cell Phones/Cordless Phones Portable Medical Devices Electronic Toys Pagers PDAs MP3 Players
LBO 3 MR 2
Pin Configurations
TOP VIEW
VBATT 1 6 VCC
MAX6439 MAX6440
5
GND
4
RESET
SOT23-6 Pin Configurations continued at end of data sheet. 1
________________________________________________________________ Maxim Integrated Products
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Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset MAX6439-MAX6442
ABSOLUTE MAXIMUM RATINGS
VBATT, VCC to GND.................................................-0.3V to +6V* Open-Drain LBO, LBOH, LBOL, LBOLH to GND ...-0.3V to +6V* Open-Drain RESET to GND ....................................-0.3V to +6V* Push-Pull RESET to GND............................-0.3V to (VCC + 0.3V) MR to GND .................................................-0.3V to (VCC + 0.3V) Input/Output Current, All Pins .............................................20mA Continuous Power Dissipation (TA = +70C) 6-Pin SOT23 (derate 8.7mW/C above +70C)............695mW 8-Pin SOT23 (derate 8.9mW/C above +70C)............714mW *Applying 7V for a duration of 1ms does not damage 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.
Operating Temperature Range .......................... -40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
ELECTRICAL CHARACTERISTICS
(VBATT = 1.2V to 5.5V, VCC = 1.2V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note1)
PARAMETER VBATT Operating Voltage Range VCC Operating Voltage Range VCC + VBATT Supply Current VBATT THRESHOLDS MAX6439UT_ J, MAX6440UT_ J MAX6439UT_ I, MAX6440UT_ I MAX6439UT_ H, MAX6440UT_ H HTH Threshold HTH MAX6439UT_ G, MAX6440UT_ G MAX6439UT_ T, MAX6440UT_ T MAX6439UT_ S, MAX6440UT_ S MAX6439UT_ R, MAX6440UT_ R MAX6439UT_ Q, MAX6440UT_ Q MAX6439UTF, MAX6440UTF MAX6439UTE, MAX6440UTE MAX6439UTD, MAX6440UTD MAX6439UTC, MAX6440UTC MAX6439UTB, MAX6440UTB LTH Threshold LTH MAX6439UTA, MAX6440UTA MAX6439UTP, MAX6440UTP MAX6439UTO, MAX6440UTO MAX6439UTN, MAX6440UTN MAX6439UTM, MAX6440UTM MAX6439UTL, MAX6440UTL MAX6439UTK, MAX6440UTK 3.510 3.413 3.315 3.218 2.535 2.438 2.340 2.243 3.023 2.925 2.828 2.730 2.633 2.535 2.048 1.950 1.853 1.755 1.658 1.560 3.60 3.50 3.40 3.30 2.60 2.50 2.40 2.30 3.10 3.00 2.90 2.80 2.70 2.60 2.10 2.00 1.90 1.80 1.70 1.60 3.690 3.588 3.485 3.383 2.665 2.563 2.460 2.358 3.178 3.075 2.973 2.870 2.768 2.665 2.153 2.050 1.948 1.845 1.743 1.640 V V SYMBOL VBATT VCC CONDITIONS TA = 0C to +85C TA = -40C to +85C TA = 0C to +85C TA = -40C to +85C MIN 1.0 1.2 1.0 1.2 2.5 TYP MAX 5.5 5.5 5.5 5.5 7 UNITS V V A
ICC + IBATT VBATT = 3.6V, VCC = 3.3V, no load (Note 2)
2
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Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset
ELECTRICAL CHARACTERISTICS (continued)
(VBATT = 1.2V to 5.5V, VCC = 1.2V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note1)
PARAMETER SYMBOL CONDITIONS MAX6441UT_ J, MAX6442UT_ J MAX6441UT_ I, MAX6442UT_ I MAX6441UT_ H, MAX6442UT_ H HTH- Threshold HTHMAX6441UT_ G, MAX6442UT_ G MAX6441UT_ T, MAX6442UT_ T MAX6441UT_ S, MAX6442UT_ S MAX6441UT_ R, MAX6442UT_ R MAX6441UT_ Q, MAX6442UT_ Q MAX6441UT_ J, MAX6442UT_ J MAX6441UT_ I, MAX6442UT_ I MAX6441UT_ H, MAX6442UT_ H HTH+ Threshold HTH+ MAX6441UT_ G, MAX6442UT_ G MAX6441UT_ T, MAX6442UT_ T MAX6441UT_ S, MAX6442UT_ S MAX6441UT_ R, MAX6442UT_ R MAX6441UT_ Q, MAX6442UT_ Q MAX6441UTF, MAX6442UTF MAX6441UTE, MAX6442UTE MAX6441UTD, MAX6442UTD MAX6441UTC, MAX6442UTC MAX6441UTB, MAX6442UTB LTH- Threshold LTHMAX6441UTA, MAX6442UTA MAX6441UTP, MAX6442UTP MAX6441UTO, MAX6442UTO MAX6441UTN, MAX6442UTN MAX6441UTM, MAX6442UTM MAX6441UTL, MAX6442UTL MAX6441UTK, MAX6442UTK MAX6441UTF, MAX6442UTF MAX6441UTE, MAX6442UTE MAX6441UTD, MAX6442UTD MAX6441UTC, MAX6442UTC MAX6441UTB, MAX6442UTB LTH+ Threshold LTH+ MAX6441UTA, MAX6442UTA MAX6441UTP, MAX6442UTP MAX6441UTO, MAX6442UTO MAX6441UTN, MAX6442UTN MAX6441UTM, MAX6442UTM MAX6441UTL, MAX6442UTL MAX6441UTK, MAX6442UTK MIN 3.510 3.413 3.315 3.218 2.535 2.438 2.340 2.243 3.686 3.583 3.481 3.378 2.662 2.559 2.457 2.355 3.023 2.925 2.828 2.730 2.633 2.535 2.048 1.950 1.853 1.755 1.658 1.560 3.174 3.071 2.969 2.867 2.764 2.662 2.150 2.048 1.945 1.843 1.740 1.638 TYP 3.600 3.500 3.400 3.300 2.600 2.500 2.400 2.300 3.780 3.675 3.570 3.465 2.730 2.625 2.520 2.415 3.100 3.000 2.900 2.800 2.700 2.600 2.100 2.000 1.900 1.800 1.700 1.600 3.255 3.150 3.045 2.940 2.835 2.730 2.205 2.100 1.995 1.890 1.785 1.680 MAX 3.690 3.588 3.485 3.383 2.665 2.563 2.460 2.358 3.875 3.767 3.659 3.552 2.798 2.691 2.583 2.476 3.178 3.075 2.973 2.870 2.768 2.665 2.153 2.050 1.948 1.845 1.743 1.640 3.337 3.229 3.121 3.014 2.906 2.798 2.260 2.153 2.045 1.937 1.830 1.722 V V V V UNITS
MAX6439-MAX6442
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Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset MAX6439-MAX6442
ELECTRICAL CHARACTERISTICS (continued)
(VBATT = 1.2V to 5.5V, VCC = 1.2V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note1)
PARAMETER LBO, LBOL, LBOH, LBOLH Timeout Period LBO, LBOL, LBOH, LBOLH Delay Time SYMBOL tLBOP tLBOD CONDITIONS VBATT rising above threshold VBATT falling below threshold (VBATT or VCC) 1.2V, ISINK = 50A, asserted low LBO, LBOL, LBOH, LBOLH Output Low (Open Drain) (VBATT or VCC) 1.6V, ISINK = 100A, asserted low VOL (VBATT or VCC) 2.7V, ISINK = 1.2mA, asserted low (VBATT or VCC) 4.5V, ISINK = 3.2mA, asserted low LBO, LBOL, LBOH, LBOLH Output Open-Drain Leakage Current ILKG Output deasserted MAX64_ _ _ _ _ _ T MAX64_ _ _ _ _ _ S MAX64_ _ _ _ _ _ R VCC Reset Threshold VTH MAX64_ _ _ _ _ _ Z MAX64_ _ _ _ _ _ Y MAX64_ _ _ _ _ _ W MAX64_ _ _ _ _ _ V VCC Reset Hysteresis VCC to RESET Delay VCC to RESET Timeout Period MR Input Voltage MR Minimum Pulse Width MR Glitch Rejection MR to RESET Delay MR Reset Timeout Period MR Pullup Resistance MR Rising Debounce Period tDEB tMRP MR to VCC (Note 3) 150 750 150 tRP VIL VIH tMPW 0.7 x VCC 1 100 200 225 1500 225 300 2250 300 VCC falling at 10mV/s from (VTH + 100mV) to (VTH - 100mV) MAX64_ _ _ _ _ _ _ D3 MAX64_ _ _ _ _ _ _ D7 150 1200 3.000 2.850 2.550 2.250 2.125 1.620 1.530 3.075 2.925 2.625 2.313 2.188 1.665 1.575 0.3 50 225 1800 300 2400 0.3 x VCC MIN 150 TYP 225 100 0.3 0.3 V 0.3 0.3 MAX 300 UNITS ms s
500 3.150 3.000 2.700 2.375 2.250 1.710 1.620
nA
V
% s ms V s ns ns ms ms
4
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Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset MAX6439-MAX6442
ELECTRICAL CHARACTERISTICS (continued)
(VBATT = 1.2V to 5.5V, VCC = 1.2V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note1)
PARAMETER RESET Output High (Push-Pull) SYMBOL CONDITIONS VCC 1.53V, ISOURCE = 100A, RESET deasserted VOH VCC 2.55V, ISOURCE = 500A, RESET deasserted VCC 1.0V, ISINK = 50A, RESET asserted RESET Output Low VOL VCC 1.2V, ISINK = 100A, RESET asserted VCC 2.12V, ISINK = 1.2mA, RESET asserted RESET deasserted MIN 0.8 x VCC V 0.8 x VCC 0.3 0.3 0.3 500 nA V TYP MAX UNITS
RESET Output Leakage Current (Open Drain)
Note 1: Production testing done at TA = +25C; limits over temperature guaranteed by design only. Note 2: The device is powered up by the highest voltage between VBATT and VCC. Note 3: MR input ignores falling input pulses, which occur within the MR debounce period (tDEB) after a valid MR reset assertion. This prevents invalid reset assertion due to switch bounce.
Typical Operating Characteristics
(VBATT = 1.2V to 5.5V, VCC = 1.2V to 5.5V, unless otherwise specified. Typical values are at TA = +25C.)
SUPPLY CURRENT vs. TEMPERATURE VCC = 3.3V, VBATT = 3.6V
MAX6439 toc01
NORMALIZED LBO TIMEOUT PERIOD vs. TEMPERATURE
MAX6439 toc02
NORMALIZED RESET TIMEOUT PERIOD vs. TEMPERATURE
NORMALIZED RESET TIMEOUT PERIOD
MAX6439 toc03
4
1.10 NORMALIZED LBO TIMEOUT PERIOD
1.015 1.010 1.005 1.000 0.995 0.990 0.985 0.980
SUPPLY CURRENT (A)
3 TOTAL 2 IBATT 1 ICC
1.05
1.00
0.95
0 -40 -20 0 20 40 60 80 TEMPERATURE (C)
0.90 -40 -20 0 20 40 60 80 TEMPERATURE (C)
-40
-20
0
20
40
60
80
TEMPERATURE (C)
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Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset MAX6439-MAX6442
Typical Operating Characteristics (continued)
(VBATT = 1.2V to 5.5V, VCC = 1.2V to 5.5V, unless otherwise specified. Typical values are at TA = +25C.)
MAXIMUM VBATT TRANSIENT DURATION vs. LTH THRESHOLD OVERDRIVE
MAX6439 toc04
MAXIMUM VCC TRANSIENT DURATION vs. VTH THRESHOLD OVERDRIVE
MAX6439 toc05
NORMALIZED UPPER (HTH) AND LOWER (LTH) TRIP VOLTAGES vs. TEMPERATURE
MAX6439 toc06
MAXIMUM VBATT TRANSIENT DURATION (s)
120 110 100 90 80 70 60 10 100 LTH THRESHOLD OVERDRIVE (mV) LBO ASSERTS ABOVE THIS LINE
60 MAXIMUM VCC TRANSIENT DURATION (s) 55 50 45 40 35 30 25 20 RESET ASSERTS ABOVE THIS LINE
1.050
NORMALIZED TRIP VOLTAGES
1.025 LOWER TRIP VOLTAGE 1.000 UPPER TRIP VOLTAGE 0.975
0.950 10 100 VTH THRESHOLD OVERDRIVE (mV) 1000 -40 -20 0 20 40 60 80 TEMPERATURE (C)
1000
NORMALIZED RESET THRESHOLD vs. TEMPERATURE
MAX6439 toc07
LBO OUTPUT vs. SINK CURRENT VCC = 3.3V, VBATT = 2.1V
MAX6439 toc08
1.050 NORMALIZED RESET THRESHOLD
120 100 LBO OUTPUT (mV) 80 60 40 20 LBO ASSERTED
1.025
1.000
0.975
0.950 -40 -20 0 20 40 60 80 TEMPERATURE (C)
0 0 2 4 6 8 10 ISINK (mA)
RESET OUTPUT vs. SINK CURRENT VCC = 2.1V, VBATT = 3.6V
MAX6439 toc09
RESET OUTPUT vs. SOURCE CURRENT VCC = 3.3V, VBATT = 3.6V
MAX6439 toc10
140 120 RESET OUTPUT (mV) 100 80 60 40 RESET ASSERTED 20 0 0 2 4 6 8
3.50
3.25 RESET OUTPUT (V) 10
3.00
2.75
2.50 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 ISINK (mA) ISOURCE (mA)
6
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Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset
Pin Description
PIN MAX6439/ MAX6440 1 MAX6441/ MAX6442 1 NAME FUNCTION Battery Voltage Input. Input for battery voltage threshold monitors and device power supply if VBATT is greater than VCC. Manual Reset Input, Active-Low, Internal 1.5k Pullup to VCC. Pull low to assert a one-shot edge-triggered RESET output for the MR reset timeout period. Leave unconnected or connect to VCC if unused. The MR input is debounced for MR rising edges to prevent false reset events. Low-Battery Output, Active Low, Open Drain. LBO is asserted when VBATT drops below the LTH specification and remains asserted until VBATT rises above the HTH specification for at least 150ms. Reset Output, Active Low, Push-Pull or Open Drain. RESET changes from high to low when the VCC input drops below the selected reset threshold and remains low for the VCC reset timeout period after VCC exceeds the reset threshold. RESET is one-shot edge-trigger pulsed low for the MR reset timeout period when the MR input is pulled low. RESET is an open-drain output for the MAX6439/MAX6441, and a push-pull output for the MAX6440/MAX6442. The push-pull outputs are referenced to VCC. RESET is guaranteed to be in the correct logic state for VBATT or VCC > 1.0V. Ground VCC Voltage Input. Input for VCC reset threshold monitor and device power supply if VCC is greater than VBATT. Low-Battery Output High, Active Low, Open Drain. LBOH is asserted when VBATT drops below the HTH- specification. LBOH is deasserted when VBATT rises above the HTH+ specification for at least 150ms. Low-Battery Output Low, Active Low, Open Drain. LBOL is asserted when VBATT drops below the LTH- specification. LBOL is deasserted when VBATT rises above the LTH+ specification for at least 150ms. Low-Battery Output Low/High, Active Low, Open Drain. LBOLH is asserted when VBATT drops below the LTH- specification. LBOLH is deasserted when VBATT rises above the HTH+ specification for at least 150ms.
MAX6439-MAX6442
VBATT
2
3
MR
3
--
LBO
4
5
RESET
5 6
2 8
GND VCC
--
6
LBOH
--
7
LBOL
--
4
LBOLH
Detailed Description
The MAX6439-MAX6442 family is available with several monitoring options. The factory-trimmed thresholds eliminate the requirement for external components. The MAX6439/MAX6440 have single low-battery outputs and the MAX6441/MAX6442 have dual low-battery outputs (see Figure 1a and Figure 1b). The MAX6439-MAX6442 combine a 1.23V reference with two comparators, logic, and timing circuitry to provide the user with information about the charge state of the power-supply batteries. The MAX6441/MAX6442
monitor separate high-voltage and low-voltage thresholds to determine battery status. The output(s) can be used to signal when the battery is charged, when the battery is low, and when the battery is empty. Factorytrimmed thresholds are ideal for monitoring single-cell Li+ or multicell alkaline/NiCd/NiMH power supplies. When the power-supply voltage drops below the specified low threshold, the low-battery output asserts. When the voltage rises above the specified high threshold following a 150ms (min) timeout period, the low-battery output is deasserted. This ensures the supply voltage
7
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Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset MAX6439-MAX6442
VBATT
VBATT
MAX6441 MAX6440
5% HYST LBO TIMEOUT PERIOD LBOH LBO HTH DETECT LBO TIMEOUT PERIOD 5% HYST LBOLH 1.23V VCC VCC 1.23V HTH DETECT LTH DETECT
LBOL
LTH DETECT R S Q Q
VCC
VTH DETECT
RESET TIMEOUT PERIOD
RESET VTH DETECT VCC RESET TIMEOUT PERIOD
RESET
MR
VCC
MR
Figure 1a. Functional Diagram
Figure 1b. Functional Diagram
has stabilized before power-converter or microprocessor activity is enabled. These devices also have an independent P supervisor that monitors VCC and provides an active-low reset output. A manual reset function is available to allow the user to reset the P with a push-button.
Low-Battery Output
The low-battery outputs are available in active-low (LBO, LBOL, LBOH, LBOLH), open-drain configurations. The low-battery outputs can be pulled to a voltage independent of VCC or VBATT, up to 5.5V. This allows the device to monitor and operate from direct battery voltage while interfacing to higher voltage microprocessors. The MAX6439/MAX6440 single-output voltage monitors provide a single low-battery output, LBO. These fixedthreshold devices assert LBO when VBATT drops below V LTH and remain asserted for at least 150ms after VBATT rises above VHTH (see Figure 2). The MAX6441/ MAX6442 triple-output voltage monitors provide three
8
low-battery outputs: LBOH, LBOL, and LBOLH. LBOH asserts when VBATT drops below VHTH- and remains asserted for at least 150ms after VBATT rises above VHTH+. LBOL asserts when VBATT drops below VLTHand remains asserted for at least 150ms after VBATT rises above VLTH+. LBOLH asserts when VBATT drops below VLTH- and remains asserted for at least 150ms after VBATT rises above VHTH+ (see Figure 3). For fastrising VBATT input, the LBOL timeout period must complete before the LBOH/LBOLH timeout period begins.
Reset Output
The MAX6439-MAX6442 provide an active-low reset output (RESET). RESET is asserted when the voltage at VCC falls below the reset threshold level. Reset remains asserted for the reset timeout period after VCC exceeds the threshold. If VCC goes below the reset threshold before the reset timeout period is completed, the internal timer restarts. The MAX6439/MAX6441 have opendrain reset outputs, while the MAX6440/MAX6442 have push-pull reset outputs (see Figure 4).
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Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset MAX6439-MAX6442
VBATT HTH
LTH tLBOP tLBOD tLBOP
LBO
Figure 2. Single Low-Battery Output Timing
HTH+ HTHLTH+ LTH-
VBATT
LBOL
tLBOP
tD
tLBOP tLBOP
LBOH
tLBOP
tD
LBOLH
Figure 3. Dual Low-Battery Output Timing
VCC VTH GND MR GND RESET GND tMPW tRP tMRP tDEB tMPW tMRP tDEB SWITCH BOUNCE SWITCH BOUNCE SWITCH BOUNCE SWITCH BOUNCE
Figure 4. RESET Timing Diagram
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Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset MAX6439-MAX6442
VHTH VBATT VLTH VHYST
CURRENTLIMITED AC WALL ADAPTER LED IN CHG GATE BATT 1-CELL Li+ BATTERY VBATT VCC LBOL DC/DC CONVERTER IN OUT SHDN
tLBOP LBO
PULSE-WIDTH SELECT INPUT TSEL
MAX1879
GND ADJ
MAX6441 MAX6442
LBOH LBOLH RESET GND
THERM
HTH = BATTERY VOLTAGE GOOD, ENABLE OPERATION. LTH = BATTERY VOLTAGE LOW, SUSPEND/DISABLE OPERATION.
THERMISTOR
Figure 5. Hysteresis
Figure 6. Li+ Charger Application (Using MAX1879)
IN Li+ 3.6V
DC/DC SHDN
OUT
LBOL VBATT
VCC LBOH NMI
VCC
logic levels, open-drain/open-collector outputs, or a momentary push-button switch to GND (the MR function is internally debounced for the tDEB timeout period) to create a manual reset function. If MR is driven from long cables, or if the device is used in a noisy environment, connect a 0.1F capacitor from MR to GND to provide additional noise immunity (see Figure 4).
Hysteresis
P
MAX6441 MAX6442
MR RESET GND
RESET GND
Hysteresis increases the comparator's noise margin by increasing the upper threshold or decreasing the lower threshold. The hysteresis prevents the output from oscillating (chattering) when VBATT is near the low-battery threshold. This is especially important for applications where the load on the battery creates significant fluctuations in battery voltages (see Figure 5).
Applications Information
Figure 7. DC-to-DC Converter Application
Li+ Battery Charger Application Manual Reset
The MAX6441/MAX6442 dual-output battery monitors can be used in conjunction with a battery charger to provide a system with additional information about the battery charge state. Many battery chargers, such as the MAX1879, provide the user with a CHG output, which tells the system when the battery is charged. The MAX6441/MAX6442 dual-output battery monitors provide three outputs, which can be used to relay the battery condition to the system. This information is useful in determining which system resources can be powered by the battery at the current charge state (see Figure 6).
Many microprocessor-based products require manual reset capability, allowing the operator, a test technician, or external logic circuitry to initiate a reset while the monitored supplies remain above their reset thresholds. These devices have a dedicated active-low MR pin. When MR is pulled low, RESET asserts a one-shot low pulse for the MR reset timeout period. The MR input has an internal 1.5k pullup resistor to VCC and can be left unconnected if not used. MR can be driven with CMOS-
10
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Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset MAX6439-MAX6442
Table 1. Factory-Trimmed Lower and Upper Threshold Combinations for Single-Cell Li+ or Three-Cell Alkaline/NiCd/NiMH Applications
VOLTAGES 2.6V LOWER THRESHOLD (LTH) 2.7V 2.8V 2.9V 3.0V 3.1V UPPER THRESHOLD (HTH) 3.3V AG BG CG DG EG FG 3.4V AH BH CH DH EH FH 3.5V AI BI CI DI EI FI 3.6V AJ BJ CJ DJ EJ FJ
Table 2. Factory-Trimmed Lower and Upper Threshold Combinations for Two-Cell Alkaline/NiCd/NiMH Applications
VOLTAGES 1.6V LOWER THRESHOLD (LTH) 1.7V 1.8V 1.9V 2.0V 2.1V UPPER THRESHOLD (HTH) 2.3V KQ LQ MQ NQ OQ PQ 2.4V KR LR MR NR OR PR 2.5V KS LS MS NS OS PS 2.6V KT LT MT NT OT PT
Table 3. Factory-Trimmed VCC Reset Threshold Levels
PART NO. SUFFIX (_) T S R Z Y W V VCC NOMINAL RESET THRESHOLD (V) 3.075 2.925 2.625 2.313 2.188 1.665 1.575
Table 4. VCC Reset Timeout Period Suffix Guide
TIMEOUT PERIOD SUFFIX D3 D7 ACTIVE TIMEOUT PERIOD (ms) MIN 150 1200 MAX 300 2400
DC-to-DC Converter Application
The MAX6441/MAX6442 triple-output battery monitors can be used in conjunction with a DC-to-DC converter to power microprocessor systems using a single Li+ cell or two to three alkaline/NiCd/NiMH cells. The LBOH output indicates that the battery voltage is weak, and is used to warn the microprocessor of potential problems. Armed with this information, the microprocessor can
reduce system power consumption. The LBOL output indicates the battery is empty, and system power should be disabled. By connecting LBOL to the SHDN pin of the DC-to-DC converter, power to the microprocessor is removed. Microprocessor power does not return until the battery has recharged to a voltage greater than VLTH+ (see Figure 7).
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11
Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset MAX6439-MAX6442
Selector Guide
PART MAX6439 MAX6440 MAX6441 MAX6442 OPEN-DRAIN RESET X -- X -- PUSH-PULL RESET -- X -- X SINGLE LOWBATTERY OUTPUT X X -- -- DUAL LOW-BATTERY OUTPUT -- -- X X
Standard Versions Table
PART MAX6439UTDHRD3 MAX6439UTDHSD3 MAX6439UTEHRD3 MAX6439UTEHSD3 MAX6439UTEIRD3 MAX6439UTEISD3 MAX6440UTDHRD3 MAX6440UTDHSD3 MAX6440UTEHRD3 MAX6440UTEHSD3 MAX6440UTEIRD3 MAX6440UTEISD3 MAX6441KADHRD3 MAX6441KADHSD3 MAX6441KAEHRD3 MAX6441KAEHSD3 MAX6441KAEIRD3 MAX6441KAEISD3 MAX6442KADHRD3 MAX6442KADHSD3 MAX6442KAEHRD3 MAX6442KAEHSD3 MAX6442KAEIRD3 MAX6442KAEISD3 TOP MARK ABMN ABMO ABMP ABMQ ABMR ABMS ABMT ABMU ABMV ABMW ABMX ABMY AEEI AEEJ AEEK AEEL AEEM AEEN AEEO AEEP AEEQ AEER AEES AEET
Li+ 3.6V
Typical Application Circuit
DC/DC
VCC MR LBO NMI
VCC
MAX6439 MAX6440
VBATT GND RESET
P RESET GND
Pin Configurations (continued)
TOP VIEW
VBATT 1 GND MR 2 3 8 7 VCC LBOL LBOH RESET
MAX6441 MAX6442
6 5
LBOLH 4
SOT23-8
Chip Information
TRANSISTOR COUNT: 1478 PROCESS: BiCMOS
12
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Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
6LSOT.EPS
MAX6439-MAX6442
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13
Low-Power, Single-/Dual-Level Battery Monitors with Hysteresis and Integrated P Reset MAX6439-MAX6442
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
SOT23, 8L.EPS
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.
14 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2002 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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