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| 19-1137; Rev 0; 9/96 4-Pin Micropower Voltage Monitors _______________General Description The MAX836/MAX837 micropower voltage monitors contain a 1.204V precision bandgap reference and a comparator in a SOT143 package. The MAX836 has an open-drain, N-channel output driver, while the MAX837 has a push-pull output driver. Two external resistors set the trip threshold voltage. ____________________________Features o 1.25% Precision Voltage Threshold o SOT143 Package o Low Cost o <5A Typical Supply Current o Open-Drain Output (MAX836) Push-Pull Output (MAX837) MAX836/MAX837 ________________________Applications Precision Battery Monitor Load Switching Battery-Powered Systems Threshold Detectors ______________Ordering Information PART* MAX836EUS-T MAX837EUS-T TEMP. RANGE -40C to +85C -40C to +85C PINMARKING PACKAGE CODE 4 SOT143 4 SOT143 AAEQ AAER *All devices available in tape-and-reel only. Contact factory for availability. __________Typical Operating Circuit VCC MAX836 ONLY GND 1.204V REF OUT __________________Pin Configuration TOP VIEW GND 1 4 OUT MAX836 MAX837 VCC VCC MAX836 MAX837 IN VCC 2 3 IN 0.1F SOT-143 ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 4-Pin Micropower Voltage Monitors MAX836/MAX837 ABSOLUTE MAXIMUM RATINGS VCC, OUT to GND (MAX836) ....................................-0.3V to 12V IN, OUT to GND (MAX837).........................-0.3V to (VCC + 0.3V) Input Current VCC .................................................................................20mA IN.....................................................................................10mA Output Current, OUT...........................................................20mA Rate of Rise, VCC ............................................................100V/s Continuous Power Dissipation SOT143 (derate 4mW/C above +70C) ......................320mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10sec) .............................+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 (VCC = +2.5V to +11.0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Operating Voltage Range (Note 1) SYMBOL VCC VIN = 1.16V, OUT = low Supply Current (Note 2) ICC VIN = 1.25V, OUT = high Trip Threshold Voltage Trip Threshold Voltage Hysteresis IN Operating Voltage Range (Note 1) IN Leakage Current (Note 3) Propagation Delay Glitch Immunity OUT Rise Time OUT Fall Time Output Leakage Current (Note 4) Output Voltage High Output Voltage Low Note 1: Note 2: Note 3: Note 4: tRT tFT ILOUT VOH VOL VTH VHYST VIN IIN tPL VIN = VTH VCC = 5.0V, 50mV overdrive VCC = 5.0V, 100mV overdrive VCC = 5.0V, no load (MAX837 only) VCC = 5.0V, no load (MAX836 pull-up = 10k) VIN > VTHMAX (MAX836 only) VIN > VTHMAX, ISOURCE = 500A (MAX837 only) VIN < VTHMIN, ISINK = 500A VCC - 0.5 0.4 3 80 35 260 680 1 VIN falling VCC = 3.6V TA = +25C TA = TMIN to TMAX TA = +25C TA = TMIN to TMAX 1.185 1.169 1.204 1.204 6 VCC - 1 12 2.0 CONDITIONS MIN 2.5 3.5 TYP MAX 11 6.5 10 15 5.0 8.0 13 1.215 1.231 V mV V nA s s ns ns A V V A UNITS V VCC = full operating range VCC = 3.6V VCC = full operating range TA = +25C TA = 0C to +70C VCC = 5V, IN = low to high The voltage-detector output remains in the direct state for VCC down to 1.2V when VIN VCC / 2. Supply current has a monotonic dependence on VCC (see Typical Operating Characteristics). IN leakage current has a monotonic dependence on VCC (see Typical Operating Characteristics). The MAX836 open-drain output can be pulled up to a voltage greater than VCC, but may not exceed 11V. 2 _______________________________________________________________________________________ 4-Pin Micropower Voltage Monitors __________________________________________Typical Operating Characteristics (VCC = +5V, RLOAD = 1M, RPULL-UP = 10k (MAX836 only), TA = +25C, unless otherwise noted.) TRIP THRESHOLD VOLTAGE vs. TEMPERATURE MAX836/7 01 MAX836/MAX837 SUPPLY CURRENT vs. SUPPLY VOLTAGE MAX836/7 02 SUPPLY CURRENT vs. IN VOLTAGE MAX836/7 03 1.207 TRIP THRESHOLD VOLTAGE (V) 1.206 1.205 1.204 1.203 1.202 1.201 -60 -40 5.0 16 14 SUPPLY CURRENT (A) 12 10 8 6 4 VCC = 3.6V 2 VCC = 11V SUPPLY CURRENT (A) 4.0 3.0 2.0 1.0 VIN = 1.22V 2 3 4 5 6 7 8 9 10 11 12 0 -20 0 20 40 60 80 100 TEMPERATURE (C) 0 0 1 2 3 4 5 6 7 8 9 10 11 12 VCC (V) VIN (V) IN LEAKAGE CURRENT vs. IN VOLTAGE MAX836/7 04 IN LEAKAGE CURRENT vs. SUPPLY VOLTAGE MAX836/7 05 MAX837 OUTPUT VOLTAGE vs. OUTPUT SOURCE CURRENT 5.0 4.5 OUTPUT VOLTAGE (V) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0.01 0.1 1 10 100 TA = +25C TA = +85C TA = -40C MAX836/7-06A 80 70 IN LEAKAGE CURRENT (nA) 60 50 40 TA = +25C 30 20 10 0 0 1 2 3 4 5 6 7 8 9 10 11 VIN (V) TA = +85C VCC = 11V TA = -40C 4.8 IN LEAKAGE CURRENT (nA) 4.4 4.0 3.6 3.2 2.8 2.4 2.0 2 VIN = 1.2V 3 4 5 6 7 8 TA = +85C 9 TA = +25C TA = -40C 5.5 10 11 12 VCC (V) OUTPUT SOURCE CURRENT (mA) OUTPUT VOLTAGE vs. OUTPUT SINK CURRENT MAX836/7-06B OUTPUT LOW VOLTAGE vs. SUPPLY VOLTAGE MAX836/7 07 SHORT-CIRCUIT SINK CURRENT vs. SUPPLY VOLTAGE SHORT-CIRCUIT SINK CURRENT (mA) TA = -40C MAX836/7 08 10,000 TA = +25C 1000 OUTPUT VOLTAGE (mV) TA = +85C TA = -40C 130 120 OUTPUT LOW VOLTAGE (mV) 110 100 90 80 70 60 50 40 30 20 ISINK = 500A 70 60 50 TA = +25C 40 30 20 10 0 TA = +85C 100 10 1 0.1 0.01 0.1 1 10 100 OUTPUT SINK CURRENT (mA) 2 3 4 5 6 7 8 9 10 11 12 2 3 4 5 6 7 8 9 10 11 12 VCC (V) VCC (V) _______________________________________________________________________________________ 3 4-Pin Micropower Voltage Monitors MAX836/MAX837 ____________________________Typical Operating Characteristics (continued) (VCC = +5V, RLOAD = 1M, RPULL-UP = 10k (MAX836 only), TA = +25C, unless otherwise noted.) VCC FALLING PROPAGATION DELAY vs. TEMPERATURE MAX836/7 09 OUT RISE/FALL TIME vs. SUPPLY VOLTAGE 1600 1400 MAX836/7 10 160 140 120 1mV/s VTRIP = 4.63V 1800 PROPAGATION DELAY (s) TIME (ns) 100 80 60 10mV/s VTRIP = 3.0V 1200 1000 800 FALL TIME 600 400 RISE TIME MAX837 ONLY VTRIP = 4.63V VTRIP = 3.0V 200 0 100 2 3 4 5 6 7 8 9 10 11 12 40 -60 -40 -20 0 20 40 60 80 TEMPERATURE (C) VCC (V) _____________________Pin Description PIN NAME GND VCC IN FUNCTION System Ground System Supply Input Noninverting Input to the Comparator. The inverting input connects to the internal 1.204V bandgap reference. Open-Drain (MAX836) or Push-Pull (MAX837) Output _______________Detailed Description The MAX836/MAX837 micropower voltage monitors contain a 1.204V precision bandgap reference and a comparator (see the Typical Operating Circuit). The only difference between the two parts is the structure of the comparator output driver. The MAX836 has an open-drain N-channel output driver that can be pulled up to a voltage higher than VCC, but under 11V. The MAX837's output is push-pull, and can both source and sink current. 1 2 3 4 OUT Programming the Trip Voltage Two external resistors set the trip voltage, VTRIP (Figure 1). VTRIP is the point at which the applied voltage (typically VCC) toggles OUT. The MAX836/MAX837's high input impedance allows large-value resistors without compromising trip-voltage accuracy. To minimize current consumption, select a value for R2 between 500k and 1M, then calculate R1 as follows: V R1 = R2 TRIP - 1 VTH VCC RPULL-UP GND OUT MAX836 VCC 0.1F VCC IN where VTRIP = desired trip voltage (in volts), VTH = threshold trip voltage (1.204V). __________Applications Information VTRIP = (1.204) R1 + R2 R2 R1 R2 Adding Hysteresis Hysteresis adds noise immunity to the MAX836/MAX837 and prevents repeated triggering when VIN is near the threshold trip voltage. Figure 2 shows how to add hysteresis to the comparator. The technique is similar for NOTE: UNITS ARE OHMS AND VOLTS Figure 1. Programming the Trip Voltage, VTRIP 4 _______________________________________________________________________________________ 4-Pin Micropower Voltage Monitors both parts. For the MAX836, select the ratio of resistors R1 and R2 so that IN sees 1.204V when the monitor voltage falls to or rises above the desired trip point (VTRIP). R3 adds hysteresis and is typically an order of magnitude larger than R1 or R2. The current through R1 and R2 should be at least 500nA to ensure that the 12nA maximum input current does not shift the trip point significantly. Capacitor C1 adds additional noise rejection. Determine the thermistor's resistance (R2) at the desired temperature. Then, using R2's resistance and half the resistance of R3, calculate R1's value with the following formula: V R1 = (R2 + R3) CC - 1 1.204 MAX836/MAX837 Monitoring Voltages Other than VCC The MAX836/MAX837 can monitor voltages other than VCC (Figure 3). Calculate VTRIP as shown in the section Programming the Trip Voltage. The monitored voltage (VMON) is independent of VCC. VIN must be 1V less than VCC. Heater Temperature Control Figure 4 shows a basic heater temperature-control circuit. Upon power-up, OUT is high and the N-channel MOSFET turns on. Current flows through the heating element (R4), warming the surrounding area. R2 is a negative-temperature-coefficient thermistor and as temperature increases, its resistance decreases. As the thermistor heats up and its resistance decreases, the MAX837's voltage at IN decreases until it reaches the 1.204V threshold voltage. At this point, OUT goes low, turning off the heating element. The thermistor cools and the voltage at IN rises until it overcomes the MAX837's hysteresis (6mV). OUT returns high when this point is reached, turning on the heating element again. This cycle repeats as long as power is applied. ___________________Chip Information TRANSISTOR COUNT: 54 GND OUT VMON MAX837 R1 VCC 0.1F R2 VCC IN Figure 3. Monitoring Voltages Other than VCC VCC GND OUT R3 VCC IN THERMISTOR WITH NEGATIVE COEFFICIENT R3 R2 C1 GND NOTE: C1 ADDS ADDITIONAL NOISE IMMUNITY OUT R1 = (R2 + R3) VCC ( 1.204 - 1 ) R2 T HEATING ELEMENT R4 OUT 0.1F R1 MAX837 VCC VCC IN MAX837 R1 0.1F Figure 2. Adding Hysteresis to the Comparator Figure 4. Heater Temperature Control 5 _______________________________________________________________________________________ 4-Pin Micropower Voltage Monitors MAX836/MAX837 __________________________________________________Tape-and-Reel Information 4.0 0.1 1.0 0.1 1.5 +0.1/-0.0 DIAMETER 2.0 0.05 1.75 0.1 A 3.5 0.05 2.2 0.1 8.0 0.3 0.5 RADIUS TYPICAL Bo 0.30 0.05 0.8 0.05 0.30R MAX. 4.0 0.1 A0 A 1.0 MINIMUM MARKING INFORMATION LOT S CODE XX XX AM = MAX8 AN = MAX8 AP = MAX8 AQ = MAX8 AR = MAX8 AS = MAX8 AT = MAX81 Ko Ao = 3.1mm 0.1 Bo = 2.7mm 0.1 Ko = 1.2mm 0.1 NOTE: DIMENSIONS ARE IN MM. AND FOLLOW EIA481-1 STANDARD. ________________________________________________________Package Information D DIM INCHES MIN MAX MILLIMETERS MIN MAX 0-8 A C A1 I e1 B A A1 B B1 C D E e e1 H I 0.031 0.001 0.014 0.030 0.0034 0.105 0.047 0.070 0.071 0.082 0.004 0.047 0.005 0.022 0.038 0.006 0.120 0.055 0.080 0.079 0.098 0.012 0.787 0.025 0.356 0.762 0.086 2.667 1.194 1.778 1.803 2.083 0.102 1.194 0.127 0.559 0.965 0.152 3.048 1.397 2.032 2.007 2.489 0.305 21-0052A E H 4-PIN SOT143 SMALL-OUTLINE TRANSISTOR PACKAGE B1 e 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. 6 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 (c) 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products. |
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