19-1137; Rev 3; 5/08 4-Pin Micropower Voltage Monitors ____________________________Features 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. o ±1.25% Precision Voltage Threshold o SOT143 Package o Low Cost o < 5µA Typical Supply Current o Open-Drain Output (MAX836) Push-Pull Output (MAX837) ________________________Applications _______________Ordering Information Precision Battery Monitor PART* Load Switching TEMP RANGE PINPACKAGE TOP MARK Battery-Powered Systems MAX836EUS-T -40°C to +85°C 4 SOT143-4 EQAA Threshold Detectors MAX837EUS-T -40°C to +85°C 4 SOT143-4 ERAA *All devices available in tape-and-reel only. Contact factory for availability. Devices are available in both leaded and lead-free packaging. Specify lead-free by replacing “-T” with “+T” when ordering. __________Typical Operating Circuit ___________________Pin Configuration VCC MAX836 ONLY GND OUT 1.204V REF GND MAX836 MAX837 VCC VCC TOP VIEW 4 OUT 3 IN MAX836 MAX837 IN VCC 0.1μF 1 2 SOT143 ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX836/MAX837 ______________General Description MAX836/MAX837 4-Pin Micropower Voltage Monitors 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/µs Continuous Power Dissipation 4-Pin SOT143 (derate 4mW/°C above +70°C).............320mW Operating Temperature Range ...........................-40°C to +85°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 (VCC = +2.5V to +11.0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.) PARAMETER Operating Voltage Range (Note 1) SYMBOL CONDITIONS VCC TYP 2.5 VIN = 1.16V, OUT = low Supply Current (Note 2) MIN VCC = 3.6V TA = +25°C 3.5 TA = TMIN to TMAX VIN = 1.25V, OUT = high VCC = 3.6V VTH Trip Threshold Voltage Hysteresis VHYST IN Operating Voltage Range (Note 1) VIN falling 11.0 V 6.5 15 TA = +25°C 2.0 TA = TMIN to TMAX 5.0 μA 8.0 VCC = full operating range Trip Threshold Voltage UNITS 10 VCC = full operating range ICC MAX 13 TA = +25°C 1.185 1.204 1.215 TA = -40°C to +85°C 1.169 1.204 1.231 VCC = 5V, IN = low to high 6 VIN V mV VCC - 1 V ±12 nA IN Leakage Current (Note 3) IIN VIN = VTH ±3 Propagation Delay tPL VCC = 5.0V, 50mV overdrive 80 µs VCC = 5.0V, 100mV overdrive 35 µs Glitch Immunity OUT Rise Time tRT VCC = 5.0V, no load (MAX837 only) 260 ns OUT Fall Time tFT VCC = 5.0V, no load (MAX836 pull-up = 10kΩ) 680 ns Output Leakage Current (Note 4) ILOUT VIN > VTHMAX (MAX836 only) Output-Voltage High VOH VIN > VTHMAX, ISOURCE = 500µA (MAX837 only) Output-Voltage Low VOL VIN < VTHMIN, ISINK = 500µA Note 1: Note 2: Note 3: Note 4: 2 ±1 VCC - 0.5 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 the Typical Operating Characteristics). IN leakage current has a monotonic dependence on VCC (see the Typical Operating Characteristics). The MAX836 open-drain output can be pulled up to a voltage greater than VCC, but may not exceed 11V. ______________________________________________________________________________________ µA V 0.4 V 4-Pin Micropower Voltage Monitors TRIP THRESHOLD VOLTAGE vs. TEMPERATURE 1.203 SUPPLY CURRENT (μA) 1.204 MAX836/7 03 14 4.0 1.205 3.0 2.0 12 10 VCC = 11V 8 6 4 1.0 VCC = 3.6V 2 VIN = 1.22V 0 1.201 -60 -40 -20 0 20 40 60 80 100 2 3 4 5 0 6 7 8 9 10 11 12 0 1 2 3 4 5 6 7 8 9 10 11 12 TEMPERATURE (°C) VCC (V) VIN (V) IN LEAKAGE CURRENT vs. IN VOLTAGE IN LEAKAGE CURRENT vs. SUPPLY VOLTAGE MAX837 OUTPUT VOLTAGE vs. OUTPUT SOURCE CURRENT 60 50 40 TA = +25°C 30 20 TA = +85°C 10 3.6 TA = +25°C 2.8 2 3 4 5 6 7 8 TA = -40°C 3.0 2.5 TA = +25°C 2.0 1.5 TA = +85°C 0.5 0 3 4 5 6 7 8 9 10 11 12 0.01 0.1 1 10 100 VCC (V) OUTPUT SOURCE CURRENT (mA) OUTPUT VOLTAGE vs. OUTPUT SINK CURRENT OUTPUT LOW VOLTAGE vs. SUPPLY VOLTAGE SHORT-CIRCUIT SINK CURRENT vs. SUPPLY VOLTAGE TA = -40°C 10 1 ISINK = 500μA 110 100 90 80 70 60 50 40 30 0.1 1 10 OUTPUT SINK CURRENT (mA) 100 TA = -40°C 60 50 TA = +25°C 40 30 TA = +85°C 20 10 0 20 0.1 70 MAX836/7 08 MAX836/7 07 120 SHORT-CIRCUIT SINK CURRENT (mA) TA = +85°C 100 130 MAX836/7-06B TA = +25°C 0.01 3.5 VIN (V) 10,000 1,000 TA = +85°C VIN = 1.2V 2 9 10 11 OUTPUT LOW VOLTAGE (mV) 1 4.0 1.0 2.0 0 4.5 4.0 2.4 0 5.0 TA = -40°C 3.2 MAX836/7-06A MAX836/7 05 4.4 IN LEAKAGE CURRENT (nA) TA = -40°C 5.5 OUTPUT VOLTAGE (V) VCC = 11V 70 4.8 MAX836/7 04 80 IN LEAKAGE CURRENT (nA) 16 MAX836/7 02 MAX836/7 01 1.206 SUPPLY CURRENT (μA) TRIP THRESHOLD VOLTAGE (V) 5.0 1.202 OUTPUT VOLTAGE (mV) SUPPLY CURRENT vs. IN VOLTAGE SUPPLY CURRENT vs. SUPPLY VOLTAGE 1.207 2 3 4 5 6 7 VCC (V) 8 9 10 11 12 2 3 4 5 6 7 8 9 10 11 12 VCC (V) _______________________________________________________________________________________ 3 MAX836/MAX837 __________________________________________Typical Operating Characteristics (VCC = +5V, RLOAD = 1MΩ, RPULLUP = 10kΩ (MAX836 only), TA = +25°C, unless otherwise noted.) _____________________________Typical Operating Characteristics (continued) (VCC = +5V, RLOAD = 1MΩ, RPULLUP = 10kΩ (MAX836 only), TA = +25°C, unless otherwise noted.) OUT RISE/FALL-TIME vs. SUPPLY VOLTAGE VCC FALLING PROPAGATION DELAY vs. TEMPERATURE 140 1mV/μs 1800 MAX836/7 10 VTRIP = 4.63V MAX836/7 09 160 1600 1400 1200 120 VTRIP = 3.0V 10mV/μs 100 80 VTRIP = 4.63V 60 VTRIP = 3.0V TIME (ns) PROPAGATION DELAY (μs) MAX836/MAX837 4-Pin Micropower Voltage Monitors RISE TIME MAX837 ONLY 1000 800 FALL TIME 600 400 40 -60 200 0 -40 0 -20 20 40 60 80 100 _____________________Pin Description PIN NAME 1 GND System Ground 2 VCC System Supply Input 3 IN 4 OUT FUNCTION Noninverting Input to the Comparator. The inverting input connects to the internal 1.204V bandgap reference. Open-Drain (MAX836) or Push-Pull (MAX837) Output VCC RPULLUP OUT GND VCC 3 4 5 6 7 8 9 10 11 12 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. 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 500kΩ and 1MΩ, then calculate R1 as follows: ⎛V ⎞ R1 = R2 ⎜ TRIP - 1⎟ ⎝ VTH ⎠ MAX836 VCC 2 VCC (V) TEMPERATURE (°C) where VTRIP = desired trip voltage (in volts), VTH = threshold trip voltage (1.204V). IN 0.1μF Applications Information VTRIP = (1.204) R1 + R2 R2 R1 NOTE: UNITS ARE OHMS AND VOLTS Figure 1. Programming the Trip Voltage, VTRIP 4 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 _______________________________________________________________________________________ 4-Pin Micropower Voltage Monitors 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 ⎝ ⎠ Monitoring Voltages Other than VCC The MAX836/MAX837 can monitor voltages other than V CC (Figure 3). Calculate V TRIP as shown in the Programming the Trip Voltage section. The monitored voltage (VMON) is independent of VCC. VIN must be 1V less than VCC. OUT GND VMON MAX837 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. R1 VCC VCC IN 0.1μF R2 Figure 3. Monitoring Voltages Other than VCC VCC OUT GND OUT 0.1μF R1 R3 MAX837 VCC VCC VCC IN THERMISTOR WITH NEGATIVE COEFFICIENT IN MAX837 T HEATING ELEMENT R4 R3 R1 0.1μF R2 R2 C1 GND NOTE: C1 ADDS ADDITIONAL NOISE IMMUNITY Figure 2. Adding Hysteresis to the Comparator OUT R1 = (R2 + R3) VCC - 1)Ω ( 1.204 Figure 4. Heater Temperature Control _______________________________________________________________________________________ 5 MAX836/MAX837 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. MAX836/MAX837 4-Pin Micropower Voltage Monitors Package Information Chip Information TRANSISTOR COUNT: 54 6 For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. PACKAGE TYPE PACKAGE CODE DOCUMENT NO. 4 SOT143 U4-1 21-0052 _______________________________________________________________________________________ 4-Pin Micropower Voltage Monitors REVISION NUMBER REVISION DATE DESCRIPTION PAGES CHANGED 0 9/96 Initial release — 1 3/04 Updated top mark information in the Ordering Information. 1 2 12/05 Added lead-free notation. 1 3 5/08 Updated top mark information in the Ordering Information. 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. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 7 © 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. MAX836/MAX837 Revision History