19-2323; Rev 1; 9/03 Low-Power, Single/Dual-Level Battery Monitors with Hysteresis Features ♦ Factory-Trimmed or User-Adjustable Threshold Options Factory-Trimmed Low Thresholds from 1.6V to 2.1V or 2.6V to 3.1V in 100mV Increments (MAX6427–MAX6432) Factory-Trimmed High Thresholds from 2.3V to 2.6V or 3.3V to 3.6V in 100mV Increments (MAX6427–MAX6432) User-Adjustable Low/High Thresholds with 615mV Internal Reference (MAX6433–MAX6438) ♦ Low Current (1µA, typ) ♦ Single or Dual Low-Battery Outputs ♦ Push-Pull LBO, Open-Drain LBO, and Open-Drain LBO Options ♦ 140ms Minimum LBO Timeout Period ♦ Immune to Short Battery Voltage Transients ♦ Guaranteed Valid LBO Logic State to BATT = 1.0V ♦ -40°C to +85°C Operating Temperature Range ♦ Small 3, 4, 5 and 6-Pin SOT Packages ♦ No External Components Required (MAX6427–MAX6432) These devices are ideal for monitoring single lithium-ion (Li+) cells 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, the lowbattery output is deasserted following a 140ms minimum timeout period. The timeout period ensures that the supply voltages have stabilized before power-converter or microprocessor activity is enabled. The MAX6427–MAX6438 family is available with several monitoring options. The MAX6427/MAX6428/MAX6429 offer factory-trimmed battery-monitor thresholds, with a single low-battery output. The MAX6430/MAX6431/MAX6432 also feature factory-trimmed thresholds, but have two lowbattery outputs. The MAX6433–MAX6438 have user-adjustable threshold voltages permitting the user to select the hysteresis range, and consequently the sensitivity of the system to noise. A wide hysteresis range also prevents chattering that can result due to battery recovery after load removal. Single low-battery outputs are supplied by the MAX6433/ MAX6434/MAX6435 and dual low-battery outputs by the MAX6436/MAX6437/MAX6438. The MAX6427–MAX6438 family is available with three output logic options for convenient interface with system power circuitry or microprocessors. The family is offered in small SOT23 and SOT143 packages and is fully specified over temperature. ________________________Applications Battery-Powered Systems (Single-Cell Li+ or Two/Three-Cell NiMH, NiCd, Alkaline) Cell Phones/Cordless Phones Pagers Portable Medical Devices PDAs Electronic Toys MP3 Players Ordering Information PART TEMP RANGE PIN-PACKAGE MAX6427_ _UR-T -40°C to +85°C 3 SOT23-3 Ordering Information continued at end of data sheet. †The MAX6427–MAX6432 are available with factory-trimmed battery-monitor thresholds. Select the desired thresholds using Tables 1 or 2 and enter the corresponding letters in the part number by replacing “_ _”. Note: There are 26 standard versions with a required order minimum of 2500 pieces. Sample stock is generally held on the standard versions only (see Standard Versions Table). Required order increment is 10,000 pieces for nonstandard versions. Contact factory for availability. All devices available in tape-and-reel only. Pin Configurations TOP VIEW LBO 1 (LBO) MAX6427 MAX6428 MAX6429 3 GND BATT 2 SOT23-3 ( ) ARE FOR THE MAX6429. Typical Operating Circuit appears at end of data sheet. Pin Configurations continued at end of data sheet. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX6427–MAX6438 General Description The MAX6427–MAX6438 are single/dual-level battery monitors with internal hysteresis. These devices are offered with single (MAX6427/MAX6428/MAX6429, MAX6433/ MAX6434/MAX6435) or dual (MAX6430/MAX6431/ MAX6432, MAX6436/MAX6437/MAX6438) low-battery output indicators, which can be used to indicate three battery conditions: battery is good (operate system in normal mode), battery is weak (operate system in low-power mode), or battery is empty (disable the system). MAX6427–MAX6438 Low-Power, Single/Dual-Level Battery Monitors with Hysteresis ABSOLUTE MAXIMUM RATINGS BATT, VDD to GND ................................................-0.3V to +6.0V HTHIN, LTHIN Inputs to GND.....................-0.3V to (VDD + 0.3V) Open-Drain LBO/LBO, LBOH/LBOH, LBOL/LBOL to GND .........................................-0.3V to +6.0V Push-Pull LBO/LBO, LBOH/LBOH, LBOL/LBOL to GND ................-0.3V to (BATT or VDD + 0.3V) Input Current (all pins) ........................................................20mA Output Current (all pins) .....................................................20mA Continuous Power Dissipation (TA = +70°C) 3-Pin SOT23-3 (derate 4.0mW/°C above +70°C) .......320mW 4-Pin SOT143-4 (derate 4.0mW/°C above +70°C) .....320mW 5-Pin SOT23-5 (derate 7.1mW/°C above +70°C) .......571mW 6-Pin SOT23-6 (derate 8.7mW/°C above +70°C) .......696mW 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 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 (BATT = 1.0V to 5.5V or VDD = 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 TA = -40°C to +85°C 1.2 5.5 TA = 0°C to +70°C 1.0 5.5 1.6 5.5 V Operating Voltage Range VBATT Operating Voltage Range VDD TA = -40°C to +85°C BATT Supply Current IBATT VBATT = 3.7V, no load (MAX6427–MAX6432) 1 1.5 µA VDD Supply Current IDD VDD = 3.7V, no load (MAX6433–MAX6438) 1 1.5 µA V FACTORY-FIXED THRESHOLDS (MAX6427–MAX6432) HTH Threshold (Note 2) VHTH Factory-fixed options, BATT rising, LBO deasserted when BATT rises above VHTH (MAX6427/MAX6428/MAX6429) -2.5 +2.5 % LTH Threshold (Note 2) VLTH Factory-fixed options, BATT falling, LBO asserted when BATT falls below VLTH (MAX6427/MAX6428/MAX6429) -2.5 +2.5 % HTH- Threshold (Note 2) VHTH- Factory-fixed options, BATT falling, LBOH asserted when BATT falls below VHTH(MAX6430/MAX6431/MAX6432) -2.5 +2.5 % HTH+ Threshold (Note 3) VHTH+ Factory-fixed options, BATT rising, LBOH deasserted when BATT rises above VHTH+ (MAX6430/MAX6431/MAX6432) -2.5 +2.5 % LTH- Threshold (Note 2) VLTH- Factory-fixed options, BATT falling, LBOL asserted when BATT falls below VLTH(MAX6430/MAX6431/MAX6432) -2.5 +2.5 % LTH+ Threshold (Note 3) VLTH+ Factory-fixed options, BATT rising, LBOL deasserted when BATT rises above VLTH+ (MAX6430/MAX6431/MAX6432) -2.5 +2.5 % 2 _______________________________________________________________________________________ Low-Power, Single/Dual-Level Battery Monitors with Hysteresis (BATT = 1.0V to 5.5V or VDD = 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 VHTHIN User-adjustable options, HTHIN rising, LBO is deasserted when HTHIN rises above VHTHIN-, VREF = 615mV (MAX6433/MAX6434/MAX6435) VLTHIN TYP MAX UNITS -2.5 +2.5 % User-adjustable options, LTHIN falling, LBOH is asserted when LTHIN falls below VLTHIN-, VREF = 615mV (MAX6433/MAX6434/MAX6435) -2.5 +2.5 % VHTHIN+ User-adjustable options, HTHIN rising, LBOH is deasserted when HTHIN rises above VHTHIN+, VREF = 615mV (MAX6436/MAX6437/MAX6438) -2.5 +2.5 % VHTHIN- User-adjustable options, HTHIN falling, LBOH is asserted when HTHIN falls below VHTHIN-, VREF = 585mV (MAX6436/MAX6437/MAX6438) -2.5 +2.5 % VLTHIN+ User-adjustable options, LTHIN rising, LBOL is deasserted when LTHIN rises above VLTHIN+, VREF = 615mV (MAX6436/MAX6437/MAX6438) -2.5 +2.5 % VLTHIN- User-adjustable options, LTHIN falling, LBOL is asserted when LTHIN falls below VLTHIN-, VREF = 585mV (MAX6436/MAX6437/MAX6438) -2.5 +2.5 % 20 nA USER-ADJUSTABLE THRESHOLDS (MAX6433–MAX6438) HTHIN Threshold (Note 4) LTHIN Threshold (Note 4) HTHIN+ Threshold (Note 4) HTHIN- Threshold (Note 5) LTHIN+ Threshold (Note 4) LTHIN- Threshold (Note 5) HTHIN/LTHIN Leakage Current (Note 6) ILKG VHTHIN or VLTHIN > 400mV _______________________________________________________________________________________ 3 MAX6427–MAX6438 ELECTRICAL CHARACTERISTICS (continued) MAX6427–MAX6438 Low-Power, Single/Dual-Level Battery Monitors with Hysteresis ELECTRICAL CHARACTERISTICS (continued) (BATT = 1.0V to 5.5V or VDD = 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 140 210 280 ms LOW-BATTERY OUTPUTS (LBO, LBO, LBOH, LBOH, LBOL, LBOL ) Timeout Period tLBOP BATT or VDD/HTHIN/LTHIN rising above threshold Delay tLBOD BATT or VDD/HTHIN/LTHIN falling below threshold LBO/LBOL/LBOH Output LOW (Push-Pull or Open-Drain) LBO Output HIGH (Push-Pull Only) (Note 7) LBO Output Leakage Current (Open-Drain Only) LBO/LBOL/LBOH Output LOW (Open-Drain Only) LBO Output Leakage Current (Open-Drain Only) VOL VOH ILKG VOL ILKG 100 BATT or VDD ≥ 1.6V, ISINK = 100µA, asserted low 0.3 BATT or VDD ≥ 2.7V, ISINK = 1.2mA, asserted low 0.3 BATT or VDD ≥ 4.5V, ISINK = 3.2mA, asserted low 0.4 BATT or VDD ≥ 1.6V, ISOURCE = 200µA, deasserted 0.8 × VSUPPLY BATT or VDD ≥ 2.7V, ISOURCE = 500µA, deasserted 0.8 × VSUPPLY BATT or VDD ≥ 4.5V, ISOURCE = 800µA, deasserted 0.8 × VSUPPLY 500 BATT or VDD ≥ 1.6V, ISINK = 100µA, deasserted low 0.3 BATT or VDD ≥ 2.7V, ISINK = 1.2mA, deasserted low 0.3 BATT or VDD ≥ 4.5V, ISINK = 3.2mA, deasserted low 0.4 LBO asserted 500 _______________________________________________________________________________________ V V LBO deasserted Note 1: Production testing done at TA = +25°C, limits over temperature guaranteed by design only. Note 2: Percentage of selected factory-fixed HTH- or LTH- threshold voltage. Note 3: Percentage of 1.05 ✕ (selected factory-fixed threshold voltage). Note 4: Percentage of 615mV voltage reference. Note 5: Percentage of 585mV voltage reference. Note 6: Guaranteed by design. Note 7: VSUPPLY is BATT or VDD. 4 µs nA V nA Low-Power, Single/Dual-Level Battery Monitors with Hysteresis 0.9 0.6 VBATT = 2V 0.3 1.005 1.000 0.995 OUTPUT ASSERTS 60 40 20 OUTPUT DOES NOT ASSERT LBO NOT ASSERTED 0 0 0.990 0 20 40 60 -40 80 -20 0 20 40 60 10 80 NORMALIZED UPPER AND LOWER TRIP VOLTAGES vs. TEMPERATURE 1000 LBO OUTPUT vs. ISINK 300 MAX6427 toc05 1.050 100 LBO COMPARATOR OVERDRIVE (mV) TEMPERATURE (°C) TEMPERATURE (°C) MAX6427 toc04 250 1.025 LBO OUTPUT (mV) -20 NORMALIZED TRIP VOLTAGES (V) -40 MAX6427 toc03 MAXIMUM TRANSIENT DURATION (µs) VBATT = 3.3V 80 MAX6427 toc02 1.5 NORMALIZED LBO TIMEOUT PERIOD VBATT = 5V SUPPLY CURRENT (µA) 1.010 MAX6427 toc01 1.8 1.2 MAXIMUM TRANSIENT DURATION vs. LBO COMPARATOR OVERDRIVE NORMALIZED LBO TIMEOUT PERIOD vs. TEMPERATURE SUPPLY CURRENT vs. TEMPERATURE LOWER TRIP VOLTAGE 1.000 UPPER TRIP VOLTAGE 200 150 100 0.975 50 0.950 OPEN-DRAIN LBO ASSERTED 0 -40 -20 0 20 40 TEMPERATURE (°C) 60 80 0 2 4 6 8 10 ISINK (mA) _______________________________________________________________________________________ 5 MAX6427–MAX6438 Typical Operating Characteristics (TA = +25°C, unless otherwise noted.) Low-Power, Single/Dual-Level Battery Monitors with Hysteresis MAX6427–MAX6438 Pin Description PIN MAX6427/ MAX6428/ MAX6429 MAX6433/ MAX6434/ MAX6435 MAX6436/ MAX6437/ MAX6438 NAME FUNCTION 1 — 4 — LBO/ LBO Low-Battery Output. LBO/LBO is asserted when BATT drops below VLTH (MAX6427/MAX6428/MAX6429) or when LTHIN (MAX6433/MAX6434/MAX6435) drops below VLTHIN, and remains asserted for at least 140ms after BATT exceeds VHTH (MAX6427/MAX6428/MAX6429) or VHTHIN (MAX6433/ MAX6434/MAX6435). 2 3 — — BATT Battery-Voltage Input. Input for battery-voltage threshold monitors and device power supply for factory-trimmed threshold versions. 3 1 2 2 GND Ground — 6 MAX6430/ MAX6431/ MAX6432 2 — 5 LBOH/ LBOH Low-Battery Output High. LBOH/LBOH is asserted when BATT drops below VHTH- (MAX6430/MAX6431/MAX6432) or when HTHIN drops below VHTHIN- (MAX6436/MAX6437/ MAX6438). It remains asserted for at least 140ms after BATT exceeds VHTH+ (MAX6430/MAX6431/MAX6432) or HTHIN rises above VHTHIN+ (MAX6436/MAX6437/MAX6438). — 4 — 4 LBOL/ LBOL Low-Battery Output Low. LBOL/LBOL is asserted when BATT drops below VLTH- (MAX6430/MAX6431/MAX6432) or when LTHIN drops below VLTHIN- (MAX6436/MAX6437/ MAX6438). It remains asserted for at least 140ms after BATT exceeds VLTH+ (MAX6430/MAX6431/MAX6432) or LTHIN rises above VLTHIN+ (MAX6436/MAX6437/MAX6438). — — 1 1 HTHIN HTH Threshold Monitor Input. A resistor-divider network sets the high threshold associated with LBOH/LBOH. — — 3 3 LTHIN LTH Threshold Monitor Input. A resistor-divider network sets the low threshold associated with LBOL/LBOL. — — 5 6 VDD VDD Supply Voltage Input. Device power supply for adjustable threshold versions. _______________________________________________________________________________________ Low-Power, Single/Dual-Level Battery Monitors with Hysteresis The MAX6427–MAX6438 family is available with several monitoring options. The MAX6427/MAX6428/MAX6429 offer factory-trimmed battery-monitor thresholds, with a single low-battery output (see Figure 1). The MAX6430/MAX6431/MAX6432 also feature factorytrimmed thresholds, but have two low-battery outputs (see Figure 2). The factory-trimmed thresholds of the MAX6427–MAX6432 eliminate the requirement for external components. The user sets the threshold voltages for the MAX6433–MAX6438, which permit the user to select the hysteresis range, and consequently the sensitivity of the system to noise. A wide hysteresis range prevents chattering that can result during battery recovery or load removal. The MAX6433/MAX6434/ MAX6435 have single low-battery outputs and the MAX6436/ MAX6437/MAX6438 have dual low-battery outputs (see Figures 3 and 4). The MAX6427–MAX6438 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 MAX6427–MAX6438 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. Factory- trimmed thresholds are ideal for monitoring single-cell Li+ or multicell alkaline/NiCd/NiMH power supplies. User-programmable versions are also available with thresholds determined using an external resistordivider (see Resistor-Value Selection).The adjustable versions can monitor down to 0.62V, making them suitable for monitoring single-cell alkaline, NiMH, and NiCd applications (VDD ≥ 1.6V). When the power-supply voltage drops below the specified low threshold, the low-battery output asserts (see Low-Battery Output). When the voltage rises above the specified high threshold following a 140ms (min) timeout period, the low-battery output is deasserted (see Threshold Monitoring). This ensures the supply voltage has stabilized before power-converter or microprocessor activity is enabled. Low-Battery Output The low-battery outputs are available in active-low (LBO, LBOH, LBOL, push-pull and open-drain) and active-high (LBO, LBOL, LBOH, open-drain) configurations. Push-pull outputs are referenced to BATT (for factory-trimmed versions) or VDD (for adjustable threshold versions). The open-drain devices can be pulled to a voltage independent of VDD or BATT, up to 5.5V. This allows the VBATT VBATT 615 + mV - R Q S Q LBO (LBO) LBO TIMEOUT PERIOD ( ) ARE FOR THE MAX6429 Figure 1. MAX6427/MAX6428/MAX6429 Functional Diagram _______________________________________________________________________________________ 7 MAX6427–MAX6438 Detailed Description MAX6427–MAX6438 Low-Power, Single/Dual-Level Battery Monitors with Hysteresis VBATT HYSTERESIS SWITCH LBO TIMEOUT PERIOD LBOL (LBOL) LBOH (LBOH) VBATT 615 + mV HYSTERESIS SWITCH ( ) ARE FOR THE MAX6432 Figure 2. MAX6430/MAX6431/MAX6432 Functional Diagram device to monitor and operate from direct battery voltage while interfacing to higher voltage microprocessors. The MAX6427/MAX6428/MAX6429/MAX6433/MAX6434/ MAX6435 single-output voltage monitors provide a single low-battery output, LBO/LBO. The MAX6427/ MAX6428/MAX6429 fixed-threshold parts assert LBO/LBO when BATT drops below V LTH . The MAX6433/MAX6434/MAX6435 adjustable-threshold parts assert LBO/LBO when the LTHIN input drops below the VLTHIN threshold (615mV) (see Figure 5). The MAX6430/MAX6431/MAX6432/MAX6436/MAX6437/ MAX6438 dual-output voltage monitors provide two lowbattery outputs, LBOH/LBOH and LBOL/LBOL. The MAX6430/MAX6431/MAX6432 fixed-threshold parts assert LBOH/LBOH when BATT drops below VHTH-, and assert LBOL/LBOL when BATT drops below VLTH-. The MAX6436/MAX6437/MAX6438 adjustable-threshold parts assert LBOH/LBOH when HTHIN drops below VHTHIN-, and assert LBOL/LBOL when LTHIN drops below VLTHIN- (see Figure 6). 8 Threshold Monitoring The MAX6433–MAX6438 HTHIN and LTHIN inputs are high-impedance inputs to comparators. An external resistor-divider network is required between the monitored voltage, HTHIN, LTHIN, and GND to select the desired thresholds (see Resistor-Value Selection). The MAX6433/MAX6434/MAX6435 single-output voltage monitors assert LBO/LBO when LTHIN drops below the internal LTHIN reference (615mV). LBO/LBO is deasserted when HTHIN rises above the internal HTHIN reference level (615mV) for at least 140ms (see Figure 6). The MAX6436/MAX6437/MAX6438 dual-output voltage monitors assert LBOL/LBOL when LTHIN drops below the LTHIN- threshold and deassert LBOL/LBOL when LTHIN rises above the LTHIN+ threshold for at least 140ms. LBOH/LBOH is asserted when HTHIN drops below the HTHIN- threshold and is deasserted when HTHIN rises above the HTHIN+ threshold for at least 140ms (see Figure 7). _______________________________________________________________________________________ Low-Power, Single/Dual-Level Battery Monitors with Hysteresis MAX6427–MAX6438 VBATT VDD LTHIN R Q S Q HTHIN VDD LBO (LBO) LBO TIMEOUT PERIOD + EXTERNAL RESISTORDIVIDER 615 mV ( ) ARE FOR THE MAX6435 Figure 3. MAX6433/MAX6434/MAX6435 Functional Diagram Hysteresis Hysteresis increases the comparator’s noise margin by increasing the upper threshold or decreasing the lower threshold (see Figure 8). The hysteresis prevents the output from oscillating (chattering) when BATT or VDD is near the low-battery threshold. This is especially important for applications where the load on the battery creates significant fluctuations in battery voltages. Fixed Hysteresis (MAX6427–MAX6432) The MAX6427/MAX6428/MAX6429 total hysteresis is the difference between the factory-trimmed VLTH and VHTH. For the MAX6430/MAX6431/MAX6432, the total hysteresis is the difference between the factory-trimmed VHTH- and VHTH+ or VLTH- and VLTH+ values, approximately 5%. Adjustable Hysteresis (MAX6433–MAX6438) Figure 7 shows the correct connections for the external resistor-dividers. To adjust the low-battery threshold and hysteresis connect resistor R1 between VDD and LTHIN, resistor R2 between LTHIN and HTHIN, and R3 between HTHIN and GND. The hysteresis for the MAX6433–MAX6438 is determined by an external resistor-divider network (see Resistor-Value Selection section of Applications Information). The hysteresis for the MAX6436/MAX6437/MAX6438 is the differences between VHTHIN- and VHTHIN+ (~5%) or VLTHIN- and VLTHIN+ (~5%). _______________________________________________________________________________________ 9 MAX6427–MAX6438 Low-Power, Single/Dual-Level Battery Monitors with Hysteresis VBATT VDD LTHIN HTHIN LBO TIMEOUT PERIOD HYSTERESIS SWITCH LBOL (LBOL) LBOH (LBOH) VBATT 615 + mV HYSTERESIS SWITCH ( ) ARE FOR THE MAX6438 Figure 4. MAX6436/MAX6437/MAX6438 Functional Diagram VHTH VBATT VLTH tLBOP tLBOP LBO Figure 5. Single Low-Battery Output Timing 10 ______________________________________________________________________________________ Low-Power, Single/Dual-Level Battery Monitors with Hysteresis MAX6427–MAX6438 VHTH+ VHTHVBATT VLTH+ VLTH- tLBOP tLBOP LBOL LBOH tLBOP tLBOP Figure 6. Dual Low-Battery Output Timing VDD LBO VDD LBO MAX6433 R1 VHTH VHYST VBATT LTHIN VLTH R2 tLBOP HTHIN R3 GND LBO HTH = BATTERY VOLTAGE GOOD, ENABLE OPERATION. LTH = BATTERY VOLTAGE LOW, SUSPEND/DISABLE OPERATION. Figure 7. Adjustable Threshold Selection Figure 8. Hysteresis ______________________________________________________________________________________ 11 MAX6427–MAX6438 Low-Power, Single/Dual-Level Battery Monitors with Hysteresis Applications Information Resistor-Value Selection (Programming the Adjustable Thresholds) MAX6433/MAX6434/MAX6435 (See Figure 5) VREF = VLTHIN = VHTHIN = 615mV R1 + R2 + R 3 VTRIPHIGH = VHTL- = VREF R3 R1 + R2 + R3 VTRIPHIGH = VHTL = VREF R3 RTOTAL = R1 + R2 + R3 R TOTAL = R1 + R2 + R 3 Use the following steps to determine values for R1, R2, and R3 of Figure 8. 1) Choose a value for RTOTAL, the sum of R1, R2, and R3. Because the MAX6433/MAX6434/MAX6435 have very high input impedances, RTOTAL can be up to 5MΩ. 2) Calculate R3 based on RTOTAL and the desired upper trip point: VREF × RTOTAL 585mV × RTOTAL = VTRIPHIGH VTRIPHIGH 3) Calculate R2 based on R TOTAL , R3, and the desired lower trip point: R2 = 615mV × RTOTAL VTRIPLOW − R3 R2 − − Use the following steps to determine values for R1, R2, and R3 of Figure 8. 1) Choose a value for RTOTAL, the sum of R1, R2, and R3. Because the MAX6436/MAX6437/MAX6438 have very high input impedances, RTOTAL can be up to 5MΩ. 2) Calculate R3 based on RTOTAL and the desired upper trip point: R3 = VREF × RTOTAL 585mV × RTOTAL = VTRIPHIGH VTRIPHIGH 3) Calculate R2 based on R TOTAL , R3, and the desired lower trip point: 585mV × RTOTAL − R3 VTRIPLOW 4) Calculate R1 based on RTOTAL, R3, and R2: R1 = RTOTAL 4) Calculate R1 based on RTOTAL, R3, and R2: R1 = RTOTAL VREF = VLTHIN- = VHTHIN- = 585mV LBOL / LBOL OUTPUT : R1 + R2 + R 3 VTRIPLOW = VLTH- = VREF R2 + R 3 LBOH / LBOH OUTPUT : R1 + R2 + R3 VTRIPLOW = VLTH = VREF R2 + R3 R3 = MAX6436/MAX6437/MAX6438 (See Figure 6) − R2 − R3 VHTH+ = VHTH- ✕ 1.05, VLTH+ = VLTH- ✕ 1.05 R3 DC-to-DC Converter Application IN VBATT BATT OUT MAX6431 LBOL SHDN LBOH GND Figure 9. DC-to-DC Converter Application 12 VCC DC/DC µP NMI GND The MAX6430/MAX6431/MAX6432 and MAX6436/ MAX6437/MAX6438 dual-output battery monitors can be used in conjunction with a step-up DC-to-DC converter to power 5V microprocessor systems using a single Li+ cell or two to three alkaline/NiCd/NiMH cells (Figure 9). 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. ______________________________________________________________________________________ Low-Power, Single/Dual-Level Battery Monitors with Hysteresis Li+ Battery Charger Application The MAX6430/MAX6431/MAX6432 and MAX6436/ MAX6437/MAX6438 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 (Figure 10). Many battery chargers, such as the MAX1879, provide the user with a CHG output, which tells the system that the battery is charged. The MAX6430/MAX6431/MAX6432 and MAX6436/MAX6437/MAX6438 dual-output battery mon- itors provide two 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. CURRENTLIMITED AC WALL ADAPTER LED GATE IN BATT CHG MAX1879 PULSE-WIDTH SELECT INPUT TSEL THERM GND ADJ 1-CELL Li+ BATTERY VBATT LBOL MAX6430 LBOH GND THERMISTOR Figure 10. Lithium-Ion Cell Charger Application (using MAX1879) Typical Operating Circuit VBATT VCC BATT µP MAX6427 LBO NMI ______________________________________________________________________________________ 13 MAX6427–MAX6438 Microprocessor power will not return until the battery has recharged to a voltage greater than HTH+ (Figure 6). MAX6427–MAX6438 Low-Power, Single/Dual-Level Battery Monitors with Hysteresis Ordering Information (continued) PART TEMP RANGE PIN-PACKAGE MAX6428_ _UR-T -40°C to +85°C 3 SOT23-3 MAX6429_ _UR-T -40°C to +85°C 3 SOT23-3 MAX6430_ _US-T -40°C to +85°C 4 SOT143-4 MAX6431_ _US-T -40°C to +85°C 4 SOT143-4 MAX6432_ _US-T -40°C to +85°C 4 SOT143-4 MAX6433UK-T -40°C to +85°C 5 SOT23-5 MAX6434UK-T -40°C to +85°C 5 SOT23-5 MAX6435UK-T -40°C to +85°C 5 SOT23-5 MAX6436UT-T -40°C to +85°C 6 SOT23-6 MAX6437UT-T -40°C to +85°C 6 SOT23-6 MAX6438UT-T -40°C to +85°C 6 SOT23-6 Pin Configurations (continued) GND 1 4 LBOL (LBOL) 3 BATT MAX6430 MAX6431 MAX6432 LBOH (LBOH) 2 SOT143-4 †The MAX6427–MAX6432 are available with factory-trimmed battery-monitor thresholds. Select the desired thresholds using Tables 1 or 2 and enter the corresponding letters in the part number by replacing “_ _”. Note: There are 26 standard versions with a required order minimum of 2500 pieces. Sample stock is generally held on the standard versions only (see Standard Versions Table). Required order increment is 10,000 pieces for nonstandard versions. Contact factory for availability. All devices available in tape-and-reel only. ( ) ARE FOR THE MAX6432 HTHIN 1 GND 2 TRANSISTOR COUNT: 905 PROCESS TECHNOLOGY: BiCMOS VDD 4 LBO (LBO) MAX6433 MAX6434 MAX6435 LTHIN 3 Chip Information 5 SOT23-5 ( ) ARE FOR THE MAX6435 HTHIN 1 GND 2 MAX6436 MAX6437 MAX6438 LTHIN 3 6 VDD 5 LBOH (LBOH) 4 LBOL (LBOL) SOT23-6 ( ) ARE FOR THE MAX6438 14 ______________________________________________________________________________________ Low-Power, Single/Dual-Level Battery Monitors with Hysteresis (LTH/LTH-) LOWER THRESHOLD UPPER THRESHOLD (HTH/HTH-) 3.4V 3.5V VOLTAGES 3.3V 2.6V AG AH AI 3.6V AJ 2.7V BG BH BI BJ 2.8V CG CH CI CJ 2.9V DG DH DI DJ 3.0V EG EH EI EJ 3.1V FG FH FI FJ Table 2. Factory-Trimmed Lower and Upper Threshold Combinations for Two-Cell Alkaline/NiCd/NiMH Applications (MAX6427–MAX6432) (LTH/LTH-) LOWER THRESHOLD UPPER THRESHOLD (HTH/HTH-) VOLTAGES 2.3V 2.4V 2.5V 2.6V 1.6V KQ KR KS KT 1.7V LQ LR LS LT 1.8V MQ MR MS MT 1.9V NQ NR NS NT 2.0V OQ OR OS OT 2.1V PQ PR PS PT Standard Versions TOP MARK PART TOP MARK FZKZ MAX6430MR KAEL MAX6427EH FZLA MAX6430OR KAEM MAX6427EI FZLB MAX6431DH KAES MAX6427MR FZLF MAX6431EH KAET MAX6427OR FZLG MAX6431EI KAEU MAX6428DH FZLC MAX6431MR KAEN KAEO ADVH PART MAX6427DH FZLD MAX6431OR MAX6428EI FZLE MAX6433UK MAX6428MR FZLH MAX6434UK ADVI ADVJ MAX6428EH FZLI MAX6435UK MAX6430DH KAEP MAX6436UT ABAB MAX6430EH KAEQ MAX6437UT ABAC KAER MAX6438UT ABAD MAX6428OR MAX6430EI ______________________________________________________________________________________ 15 MAX6427–MAX6438 Table 1. Factory-Trimmed Lower and Upper Threshold Combinations for Single-Cell Li+ or Three-Cell Alkaline/NiCd/NiMH Applications (MAX6427–MAX6432) MAX6427–MAX6438 Low-Power, Single/Dual-Level Battery Monitors with Hysteresis Selector Guide ACTIVELOW PUSHPULL OUTPUT ACTIVELOW OPENDRAIN OUTPUT ACTIVEHIGH OPENDRAIN OUTPUT SINGLE OUTPUT DUAL OUTPUT — — — — — — — — — — — — — — — — — — — — MAX6432 — — — — MAX6433 — — — — MAX6434 — — — — MAX6435 — — — — MAX6436 — — — — MAX6437 — — — — MAX6438 — — — — PART FACTORYFIXED THRESHOLDS USERADJUSTABLE THRESHOLDS MAX6427 MAX6428 MAX6429 MAX6430 MAX6431 16 ______________________________________________________________________________________ Low-Power, Single/Dual-Level Battery Monitors with Hysteresis SOT23 L.EPS PACKAGE OUTLINE, 3L SOT-23 21-0051 F 1 1 ______________________________________________________________________________________ 17 MAX6427–MAX6438 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.) 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.) SOT-143 4L.EPS MAX6427–MAX6438 Low-Power, Single/Dual-Level Battery Monitors with Hysteresis PACKAGE OUTLINE, SOT-143, 4L 21-0052 18 ______________________________________________________________________________________ E 1 1 Low-Power, Single/Dual-Level Battery Monitors with Hysteresis SOT-23 5L .EPS PACKAGE OUTLINE, SOT-23, 5L 21-0057 E 1 1 ______________________________________________________________________________________ 19 MAX6427–MAX6438 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.) 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.) 6LSOT.EPS MAX6427–MAX6438 Low-Power, Single/Dual-Level Battery Monitors with Hysteresis PACKAGE OUTLINE, SOT-23, 6L 21-0058 F 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. 20 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 © 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.