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19-2947; Rev 1; 11/05
Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated P Reset
General Description
The MAX6846-MAX6849 are a family of ultra-low-power battery monitors with integrated microprocessor (P) supervisors. The user-adjustable 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 lowpower 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 pushbutton. The MAX6846-MAX6849 are ideal for single-cell lithiumion (Li+) or multicell alkaline/NiCd/NiMH applications. When the battery voltage drops below each adjusted low threshold, the low-battery outputs are asserted to alert the system. When the voltage rises above the adjusted 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. These devices have user-adjustable battery threshold voltages, providing a wide hysteresis range to prevent chattering that can result due to battery recovery after load removal. Single low-battery outputs are supplied by the MAX6846/MAX6847 and dual low-battery outputs are supplied by the MAX6848/MAX6849. All battery monitors have open-drain low-battery outputs. The MAX6846-MAX6849 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 MAX6846/ MAX6848 are offered with an open-drain RESET output and the MAX6847/MAX6849 are offered with a pushpull RESET output. The MAX6846-MAX6849 are offered in a SOT23 package and are fully specified over a -40C to +85C temperature range.
Features
User-Adjustable Thresholds for Monitoring Single-Cell Li+ or Multicell Alkaline/NiCd/NiMH Applications Single and Dual Low-Battery Output Options Independent P Reset with Manual Reset Factory-Set Reset Thresholds for Monitoring 1.8V to 3.3V Systems Available with 150ms (min) or 1.2s (min) VCC Reset Timeout Period Options 150ms (min) LBO Timeout Period Immune to Short-Battery Voltage Transients Low Current (2.5A, typ at 3.6V) -40C to +85C Operating Temperature Range Small 8-Pin SOT23 Packages
MAX6846-MAX6849
Ordering Information
PART MAX6846KA_D_-T MAX6847KA_D_-T MAX6848KA_D_-T MAX6849KA_D_-T TEMP RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 8 SOT23-8 8 SOT23-8 8 SOT23-8 8 SOT23-8
Note: The first "_" is the VCC reset threshold level, suffix found in Table 1. The "_" after the D is a placeholder for the reset timeout period suffix found in Table 2. All devices are available in tape-and-reel only. There is a 2500 piece minimum order increment for standard versions (see Standard Versions table). Sample stock is typically held on standard versions only. Nonstandard versions require a minimum order increment of 10,000 pieces. Contact factory for availability. Devices are available in both leaded and lead-free packaging. Specify lead-free by replacing "-T" with "+T" when ordering.
Applications
Battery-Powered Systems (Single-Cell Li+ or Multicell NiMH, NiCd, Alkaline) Cell Phones/Cordless Phones Portable Medical Devices Digital Cameras Pagers PDAs MP3 Players Electronic Toys
TOP VIEW
Pin Configurations
VDD GND LTHIN
1 2 3
8 7
VCC HTHIN MR RESET
VDD GND LTHIN
1 2 3
8 7
VCC HTHIN LBOH RESET
MAX6846 MAX6847
6 5
MAX6848 MAX6849
6 5
LBO 4
LBOL 4
SOT23
SOT23
________________________________________________________________ Maxim Integrated Products
1
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Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated P Reset MAX6846-MAX6849
ABSOLUTE MAXIMUM RATINGS
VDD, VCC to GND ....................................................-0.3V to +6V* Open-Drain LBO, LBOH, LBOL 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) HTHIN, LTHIN to GND................................-0.3V to (VDD + 0.3V) MR to GND .................................................-0.3V to (VCC + 0.3V) Input/Output Current, All Pins .............................................20mA *Applying 7V for a duration of 1ms does not damage the device. Continuous Power Dissipation (TA = +70C) 8-Pin SOT23 (derate 8.9mW/C above +70C)............714mW Operating Temperature Range .......................... -40C to +85C Junction Temperature ......................................................+150C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C
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
(VDD = 1.6V to 5.5V, VCC = 1.2V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1)
PARAMETER VDD Operating Voltage Range VCC Operating Voltage Range VCC + VDD Supply Current SYMBOL VDD VCC ICC + IDD TA = 0C to +85C TA = -40C to +85C VDD = 3.6V, VCC = 3.3V, no load (Note 2) HTHIN rising, LBO is deasserted when HTHIN rises above VHTH LTHIN falling, LBO is asserted when LTHIN falls below VLTH HTHIN rising, LBOH is deasserted when HTHIN rises above VHTH+ HTHIN falling, LBOH is asserted when HTHIN falls below VHTHLTHIN rising, LBOL is deasserted when LTHIN rises above VLTH+ LTHIN falling, LBOL is asserted when LTHIN falls below VLTHVHTHIN or VLTHIN 400mV HTHIN/LTHIN rising above threshold HTHIN/LTHIN falling below threshold (VDD or VCC) 1.2V, ISINK = 50A, asserted low (VDD or VCC) 1.6V, ISINK = 100A, asserted low VOL (VDD or VCC) 2.7V, ISINK = 1.2mA, asserted low (VDD or VCC) 4.5V, ISINK = 3.2mA, asserted low 150 225 100 0.3 0.3 V 0.3 0.3 CONDITIONS MIN 1.6 1.0 1.2 2.5 TYP MAX 5.5 5.5 5.5 7 UNITS V V A
MAX6846/MAX6847 VDD THRESHOLDS HTHIN Threshold LTHIN Threshold VHTH VLTH 600 600 615 615 630 630 mV mV
MAX6848/MAX6849 VDD THRESHOLDS HTHIN+ Threshold HTHIN- Threshold LTHIN+ Threshold LTHIN- Threshold MAX6846-MAX6849 HTHIN/LTHIN Leakage Current LBO, LBOL, LBOH Timeout Period LBO, LBOL, LBOH Delay Time ILKG tLBOP tLBOD 20 300 nA ms s VHTH+ VHTHVLTH+ VLTH600 567 600 567 615 582 615 582 630 597 630 597 mV mV mV mV
LBO, LBOL, LBOH Output Low
2
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Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated P Reset
ELECTRICAL CHARACTERISTICS (continued)
(VDD = 1.6V to 5.5V, VCC = 1.2V to 5.5V, TA = -40C to +85C, unless otherwise specified. Typical values are at TA = +25C.) (Note 1)
PARAMETER LBO, LBOL, LBOH Output Open-Drain Leakage Current SYMBOL CONDITIONS Output deasserted MAX68_ _ _ _ T MAX68_ _ _ _ S MAX68_ _ _ _ R VCC Reset Threshold VTH MAX68_ _ _ _ Z MAX68_ _ _ _ Y MAX68_ _ _ _ W MAX68_ _ _ _ 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 RESET Output High (Push-Pull) tDEB tMRP MR to VCC (Note 3) 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 150 750 150 0.8 x VCC V 0.8 x VCC 0.3 0.3 0.3 500 nA V tRD 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) MAX68_ _ _ _ _ D3 MAX68_ _ _ _ _ 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 TYP MAX 500 3.150 3.000 2.700 2.375 2.250 1.710 1.620 % s ms V s ns ns ms ms V UNITS nA
MAX6846-MAX6849
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 VDD 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.
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Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated P Reset MAX6846-MAX6849
Typical Operating Characteristics
(VDD = 3.6V, VCC = 3.3V, unless otherwise specified. Typical values are at TA = +25C.)
SUPPLY CURRENT vs. TEMPERATURE
MAX6846-49 toc01
NORMALIZED LBO TIMEOUT PERIOD vs. TEMPERATURE
MAX6846-49 toc02
NORMALIZED RESET TIMEOUT PERIOD vs. TEMPERATURE
NORMALIZED RESET TIMEOUT PERIOD
MAX6846-49 toc03
4 VCC = 3.3V, VDD = 3.6V 3 TOTAL 2
1.10 NORMALIZED LBO TIMEOUT PERIOD
1.100
SUPPLY CURRENT (A)
1.05
1.050
IDD ICC
1.00
1.000
1
0.95
0.950
0 -40 -20 0 20 40 60 80 TEMPERATURE (C)
0.90 -40 -20 0 20 40 60 80 TEMPERATURE (C)
0.900 -40 -20 0 20 40 60 80 TEMPERATURE (C)
MAXIMUM VLTH/VHTH TRANSIENT DURATION vs. THRESHOLD OVERDRIVE
MAXIMUM VLTH/VHTH TRANSIENT DURATION (s)
MAX6846-49 toc04
MAXIMUM VCC TRANSIENT DURATION vs. THRESHOLD OVERDRIVE
MAXIMUM VCC TRANSIENT DURATION (s) 90 80 70 60 50 40 30 20 10 100 THRESHOLD OVERDRIVE (mV) 1000 RESET OCCURS ABOVE THIS LINE
MAX6846-49 toc05
120 110 LBO ASSERTS ABOVE THIS LINE 100 90 80 70 60 10 100 THRESHOLD OVERDRIVE (mV)
100
1000
4
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Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated P Reset MAX6846-MAX6849
Typical Operating Characteristics (continued)
(VDD = 3.6V, VCC = 3.3V, unless otherwise specified. Typical values are at TA = +25C.)
NORMALIZED UPPER AND LOWER LBO TRIP VOLTAGES vs. TEMPERATURE
MAX6846-49 toc06
NORMALIZED RESET THRESHOLD vs. TEMPERATURE
MAX6846-49 toc07
LBO OUTPUT vs. SINK CURRENT
VCC = VDD = 3.3V 100 LBO OUTPUT (mV) 80 60 40 20
MAX6846-49 toc08
1.050 NORMALIZED LBO TRIP VOLTAGES
1.050 NORMALIZED RESET THRESHOLD
120
1.025
1.025
1.000
1.000
0.975
0.975
0.950 -40 -20 0 20 40 60 80 TEMPERATURE (C)
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
MAX6846-49 toc09
RESET OUTPUT vs. SOURCE CURRENT
VCC = 3.3V, VDD = 3.6V 3.25 RESET OUTPUT (V)
MAX6846-49 toc10
140 VCC = 2.1V, VDD = 3.6V 120 RESET OUTPUT (mV) 100 80 60 40 20 0 0 2 4 6 8
3.50
3.00
2.75
2.50 10 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 ISINK (mA) ISOURCE (mA)
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5
Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated P Reset MAX6846-MAX6849
Pin Description
PIN MAX6846/MAX6847 MAX6848/MAX6849 1 2 3 1 2 3 NAME VDD GND LTHIN FUNCTION VDD Supply. Device power supply if VDD is greater than VCC. Ground LTH Threshold Monitor Input. A resistor-divider network sets the low threshold associated with LBOL and LBO. Low-Battery Output, Active-Low, Open-Drain. LBO is asserted when LTHIN drops below the VLTH specification and remains asserted until HTHIN rises above the VHTH specification for at least 150ms. Reset Output, Active-Low, Push-Pull, or Open-Drain. RESET goes 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 MAX6846/MAX6848, and a push-pull output for the MAX6847/MAX6849. The push-pull outputs are referenced to VCC. RESET is guaranteed to be in the correct logic state for VDD or VCC 10V. Manual Reset Input, Active-Low, Internal 1.5k Pullup to VCC. Pull MR low to assert a one-shot reset output pulse 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. HTH Threshold Monitor Input. A resistor-divider network sets the high threshold associated with LBOH and LBO. VCC Voltage Input. Input for VCC reset threshold monitor and device power supply if VCC is greater than VDD. Low-Battery Output High, Active-Low, Open-Drain. LBOH is asserted when HTHIN drops below the VHTH- specification. LBOH is deasserted when HTHIN rises above the VHTH+ specification for at least 150ms. Low-Battery Output Low, Active-Low, Open-Drain. LBOL is asserted when LTHIN drops below the VLTH- specification. LBOL is deasserted when LTHIN rises above the VLTH+ specification for at least 150ms.
4
--
LBO
5
5
RESET
6
--
MR
7 8
7 8
HTHIN VCC
--
6
LBOH
--
4
LBOL
Detailed Description
The MAX6846-MAX6849 family is available with several monitoring options. The MAX6846/MAX6847 have single low-battery outputs and the MAX6848/MAX6849 have dual low-battery outputs (see Figures 1a and 1b). The MAX6846-MAX6849 combine a 615mV reference with two comparators, logic, and timing circuitry to provide the user with information about the charge state of the power-supply batteries. The MAX6848/MAX6849 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. User6
adjustable thresholds are ideal for monitoring singlecell 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 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 pushbutton.
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Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated P Reset MAX6846-MAX6849
VDD LTHIN LTH DETECT HTHIN R S HTH DETECT LBO TIMEOUT PERIOD Q
VDD
MAX6847
LTHIN LTH DETECT HTHIN Q LBO 5% HYST
MAX6848
LBOL
LBO TIMEOUT PERIOD HTH DETECT 5% HYST LBOH
615mV VCC 615mV VCC VCC
VTH DETECT
RESET TIMEOUT PERIOD
RESET RESET VTH DETECT RESET TIMEOUT PERIOD
1.23V
VCC 1.23V
MR
Figure 1a. MAX6847 Functional Diagram
Figure 1b. MAX6848 Functional Diagram
Low-Battery Output
The low-battery outputs are available in active-low (LBO, LBOL, LBOH), open-drain configurations. The low-battery outputs can be pulled to a voltage independent of VCC or VDD, up to 5.5V. This allows the device to monitor and operate from direct battery voltage while interfacing to higher voltage microprocessors. The MAX6846/MAX6847 single-output voltage monitors provide a single low-battery output, LBO. LBO asserts when LTHIN drops below VLTH and remains asserted for at least 150ms after HTHIN rises above VHTH (see Figure 2). The MAX6848/MAX6849 dual-output voltage monitors provide two low-battery outputs: LBOH and LBOL. LBOH asserts when HTHIN drops below VHTHand remains asserted for at least 150ms after HTHIN
rises above VHTH+. LBOL asserts when LTHIN drops below VLTH- and remains asserted for at least 150ms after LTHIN rises above VLTH+ (see Figure 3). For fastrising VDD input, the LBOL timeout period must complete before the LBOH timeout period begins.
Reset Output
The MAX6846-MAX6849 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 (see Figure 4). The MAX6846/ MAX6848 have open-drain reset outputs, while the MAX6847/MAX6849 have push-pull reset outputs.
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7
Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated P Reset MAX6846-MAX6849
VMONITORED VTRIPHIGH HTH HTHIN = 615mV VHYST VTRIPLOW LTH tLBOP LTHIN = 615mV
LBO VHYST = HYSTERESIS
tLBOD
tLBOP
Figure 2. Single Low-Battery Output Timing
(VTRIPHIGH +5%) HTH+ HTHVTRIPHIGH (VTRIPLOW +5%) LTH+ LTHVTRIPLOW
VMONITORED
HTHIN = 615mV VHYST = 5% HTHIN = 582mV LTHIN = 615mV VHYST = 5% LTHIN = 582mV tLBOD
LBOL
tLBOP
tLBOP tLBOP
LBOH VHYST = HYSTERESIS
tLBOP
tLBOD
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
8
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Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated P Reset
Manual Reset
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 CMOSlogic levels, open-drain/open-collector outputs, or a momentary pushbutton 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).
VDD VDD LBO*
MAX6846-MAX6849
R1
LTHIN R2 HTHIN
MAX6846 MAX6847 MAX6848 MAX6849
(LBOH) (LBOL) GND
R3
* FOR THE MAX6846/MAX6847. ( ) FOR THE MAX6848/MAX6849.
Hysteresis
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 monitor input 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 Figures 2 and 3). For the MAX6846/MAX6847, hysteresis is set using three external resistors (see Figure 5). The MAX6848/MAX6849 have dual, low-battery input levels. Each input level has a 5% (typ) hysteresis.
Figure 5. Adjustable Threshold Selection
2) Calculate R3 based on R TOTAL and the desired upper trip point: R3 = 615mV x RTOTAL VTRIPHIGH
3) Calculate R2 based on RTOTAL, R3, and the desired lower trip point: 615mV x RTOTAL R2 = - R3 VTRIPLOW 4) Calculate R1 based on RTOTAL, R3, and R2: R1 = RTOTAL - R2 - R3 MAX6848/MAX6849 VLTH- = VHTH- = 582mV LBOL low-trip level: R1 + R2 + R3 VTRIPLOW = VLTH- x R2 + R3 LBOH low-trip level: R1 + R2 + R3 VTRIPHIGH = VHTH- x R3 RTOTAL = R1 + R2 + R3 Use the following steps to determine values for R1, R2, and R3 of Figure 5.
9
Applications Information
Resistor-Value Selection (Programming the Adjustable Thresholds)
MAX6846/MAX6847 VLTH = VHTH = 615mV R1 + R2 + R3 VTRIPLOW = VLTH x R2 + R3 R1 + R2 + R3 VTRIPHIGH = VHTH x R3 RTOTAL = R1 + R2 + R3 Use the following steps to determine values for R1, R2, and R3 of Figure 5. 1) Choose a value for RTOTAL, the sum of R1, R2, and R3. Because the MAX6846/MAX6847 have very high input impedance, RTOTAL can be up to 500k.
_______________________________________________________________________________________
Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated P Reset MAX6846-MAX6849
1) Choose a value for RTOTAL, the sum of R1, R2, and R3. Because the MAX6848/MAX6849 have very high input impedance, RTOTAL can be up to 500k. 2) Calculate R3 based on R TOTAL and the desired upper trip point: R3 = 582mV x RTOTAL VTRIPHIGH 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-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).
3) Calculate R2 based on RTOTAL, R3, and the desired lower trip point: 582mV x RTOTAL R2 = - R3 VTRIPLOW 4) Calculate R1 based on RTOTAL, R3, and R2: R1 = RTOTAL - R2 - R3 5) LBOL high-trip level: VTRIPLOW 1.05 6) LBOH high-trip level: VTRIPHIGH 1.05
Table 1. 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
Monitoring Multicell Battery Applications
For monitoring multicell Li+ (or a higher number of alkaline/NiCd/NiMH cells), connect VDD to a supply voltage between 1.6V to 5.5V. Figure 6 shows VDD connected directly to VCC. To calculate the values of R1, R2, and R3, see the Resistor-Value Selection section.
Table 2. VCC Reset Timeout Period Suffix Guide
TIMEOUT PERIOD SUFFIX D3 D7 ACTIVE TIMEOUT PERIOD (ms) MIN 150 1200 MAX 300 2400
DC-DC Converter Application
The MAX6848/MAX6849 dual battery monitors can be used in conjunction with a DC-DC converter to power microprocessor systems using a single Li+ cell or two
VCC VMONITORED VDD VCC LBO*
IN Li+ 3.6V VDD
DC-DC SHDN
OUT
R1 LTHIN R2 HTHIN R3
MAX6846 MAX6847 MAX6848 MAX6849
LBOL
VCC LBOH NMI
VCC
(LBOL) LTHIN (LBOH) GND P
MAX6848 MAX6849
HTHIN GND RESET RESET GND
* FOR THE MAX6846/MAX6847. ( ) FOR THE MAX6848/MAX6849.
Figure 6. Monitoring Multicell Li+ Applications 10
Figure 7. DC-DC Converter Application
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Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated P Reset MAX6846-MAX6849
Selector Guide
PART MAX6846 MAX6847 MAX6848 MAX6849 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 MAX6846KARD3 MAX6846KASD3 MAX6846KAWD3 MAX6846KAZD3 MAX6847KARD3 MAX6847KASD3 MAX6847KAWD3 MAX6847KAZD3 MAX6848KARD3 MAX6848KASD3 MAX6848KAWD3 MAX6848KAZD3 MAX6849KARD3 MAX6849KASD3 MAX6849KAWD3 MAX6849KAZD3 TOP MARK AEJI AEJD AEJK AEJJ AEJE AEJL AEJN AEJM AEJP AEJO AEJR AEJQ AEJT AEJS AEJV AEJU
Li+ 3.6V
Typical Application Circuit
DC-DC VCC LBO NMI
VCC MR
VDD MAX6846
MAX6847
LTHIN RESET
P
RESET
HTHIN
GND
GND
Chip Information
TRANSISTOR COUNT: 1478 PROCESS: BiCMOS
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11
Low-Power, Adjustable Battery Monitors with Hysteresis and Integrated P Reset MAX6846-MAX6849
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.)
SOT23, 8L .EPS
REV.
SEE DETAIL "A" b e
C L
SYMBOL A A1 A2 b C D E E1 L L2 e e1
MIN 0.90 0.00 0.90 0.28 0.09 2.80 2.60 1.50 0.30
MAX 1.45 0.15 1.30 0.45 0.20 3.00 3.00 1.75 0.60 0.25 BSC.
C L
E
C L
E1
PIN 1 I.D. DOT (SEE NOTE 6) e1 D C
C L
0
0.65 BSC. 1.95 REF. 0 8
L2 A A2 A1
SEATING PLANE C
GAUGE PLANE
NOTE:
1. ALL DIMENSIONS ARE IN MILLIMETERS. 2. FOOT LENGTH MEASURED FROM LEAD TIP TO UPPER RADIUS OF HEEL OF THE LEAD PARALLEL TO SEATING PLANE C. 3. PACKAGE OUTLINE EXCLUSIVE OF MOLD FLASH & METAL BURR. 4. PACKAGE OUTLINE INCLUSIVE OF SOLDER PLATING. 5. COPLANARITY 4 MILS. MAX. 6. PIN 1 I.D. DOT IS 0.3 MM y MIN. LOCATED ABOVE PIN 1. 7. SOLDER THICKNESS MEASURED AT FLAT SECTION OF LEAD BETWEEN 0.08mm AND 0.15mm FROM LEAD TIP. 8. MEETS JEDEC MO178.
L
0
DETAIL "A"
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, SOT-23, 8L BODY
APPROVAL DOCUMENT CONTROL NO.
21-0078
D
1 1
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.

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