19-1512; Rev 1; 1/07 SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference The MAX917–MAX920 nanopower comparators in space-saving SOT23 packages feature Beyond-theRails™ inputs and are guaranteed to operate down to +1.8V. The MAX917/MAX918 feature an on-board 1.245V ±1.5% reference and draw an ultra-low supply current of only 750nA, while the MAX919/MAX920 (without reference) require just 380nA of supply current. These features make the MAX917–MAX920 family of comparators ideal for all 2-cell battery applications, including monitoring/management. The unique design of the output stage limits supply-current surges while switching, virtually eliminating the supply glitches typical of many other comparators. This design also minimizes overall power consumption under dynamic conditions. The MAX917/MAX919 have a push-pull output stage that sinks and sources current. Large internal output drivers allow rail-to-rail output swing with loads up to 8mA. The MAX918/MAX920 have an open-drain output stage that makes them suitable for mixed-voltage system design. Features ♦ Ultra-Low Supply Current 380nA per Comparator (MAX919/MAX920) 750nA per Comparator with Reference (MAX917/MAX918) ♦ Guaranteed to Operate Down to +1.8V ♦ Internal 1.245V ±1.5% Reference (MAX917/MAX918) ♦ Input Voltage Range Extends 200mV Beyond-the-Rails ♦ CMOS Push-Pull Output with ±8mA Drive Capability (MAX917/MAX919) ♦ Open-Drain Output Versions Available (MAX918/MAX920) ♦ Crowbar-Current-Free Switching ♦ Internal Hysteresis for Clean Switching ♦ No Phase Reversal for Overdriven Inputs ♦ Space-Saving SOT23 Package Ordering Information Applications 2-Cell Battery Monitoring/Management PART PIN-PACKAGE TOP MARK PKG CODE ADIQ U5-1 Ultra-Low-Power Systems MAX917EUK-T 5 SOT23-5 Mobile Communications MAX917ESA 8 SO Notebooks and PDAs MAX918EUK-T 5 SOT23-5 MAX918ESA 8 SO Threshold Detectors/Discriminators Sensing at Ground or Supply Line MAX919EUK-T 5 SOT23-5 MAX919ESA 8 SO Telemetry and Remote Systems MAX920EUK-T 5 SOT23-5 Medical Instruments MAX920ESA 8 SO — S8-4 ADIR U5-1 — S8-4 ADIS U5-1 — S8-4 ADIT U5-1 — S8-4 Note: All devices are specified over the -40°C to +85°C operating temperature range. Selector Guide PART INTERNAL REFERENCE OUTPUT TYPE SUPPLY CURRENT (nA) MAX917 Yes Push-Pull 750 MAX918 Yes Open-Drain 750 MAX919 No Push-Pull 380 MAX920 No Open-Drain 380 Typical Application Circuit appears at end of data sheet. Beyond-the-Rails is a trademark of Maxim Integrated Products, Inc. Pin Configurations TOP VIEW OUT 1 VEE 2 VCC 4 IN- (REF) MAX917 MAX918 MAX919 MAX920 IN+ 3 ( ) ARE FOR MAX917/MAX918. 5 SOT23-5 Pin Configurations continue 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 MAX917–MAX920 General Description MAX917–MAX920 SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference ABSOLUTE MAXIMUM RATINGS Supply Voltage (VCC to VEE)..................................................+6V Voltage Inputs (IN+, IN-, REF) .........(VEE - 0.3V) to (VCC + 0.3V) Current Into Input Pins......................................................±20mA Output Voltage MAX917/MAX919 ........................(VEE - 0.3V) to (VCC + 0.3V) MAX918/MAX920 ......................................(VEE - 0.3V) to +6V Output Current..................................................................±50mA Output Short-Circuit Duration .............................................10sec Continuous Power Dissipation (TA = +70°C) 5-Pin SOT23 (derate 7.31mW/°C above +70°C).........571mW 8-Pin SO (derate 5.88mW/°C above +70°C)...............471mW Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +150°C Lead Temperature (soldering, 10sec) .............................+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—MAX917/MAX918 (VCC = +5V, VEE = 0V, VIN+ = VREF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Supply Voltage Range SYMBOL VCC CONDITIONS Inferred from the PSRR test MIN VCC = 1.8V Supply Current ICC VCC = 5V TA = TMIN to TMAX Inferred from the output swing test Input Offset Voltage VOS (Note 2) Input-Referred Hysteresis VHB (Note 3) Power-Supply Rejection Ratio Output-Voltage Swing High Output-Voltage Swing Low PSRR 2 µA 1 5 10 MAX917 only, VCC = 1.8V, ISOURCE = 1mA VCC = 5V, ISINK = 8mA TA = +25°C 0.1 1 190 400 TA = TMIN to TMAX 500 55 200 190 400 TA = TMIN to TMAX 500 55 TA = TMIN to TMAX MAX918 only, VO = 5.5V VCC = 5V mV nA mV/V mV 300 TA = TMIN to TMAX TA = +25°C V mV 1 2 TA = +25°C Sinking, VO = VCC 1.30 4 TA = +25°C ISC V VCC + 0.2 0.15 MAX917 only, VCC = 5V, ISOURCE = 8mA Sourcing, VO = VEE Output Short-Circuit Current VEE - 0.2 TA = TMIN to TMAX VCC = 1.8V to 5.5V VOL UNITS 5.5 1.60 TA = TMIN to TMAX VCC - VOH ILEAK TA = +25°C TA = +25°C VCC = 1.8V, ISINK = 1mA Output Leakage Current 0.80 TA = +25°C VIN+ IB MAX 0.75 IN+ Voltage Range Input Bias Current TYP 1.8 200 mV 300 0.001 1 µA 95 VCC = 1.8V 8 VCC = 5V 98 VCC = 1.8V 10 _______________________________________________________________________________________ mA SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference MAX917–MAX920 ELECTRICAL CHARACTERISTICS—MAX917/MAX918 (continued) (VCC = +5V, VEE = 0V, VIN+ = VREF, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER High-to-Low Propagation Delay (Note 4) SYMBOL tPD- CONDITIONS VCC = 5V 22 tPD+ MAX918 only VCC = 1.8V 30 VCC = 5V 95 VCC = 1.8V, RPULLUP = 100kΩ 35 VCC = 5V, RPULLUP = 100kΩ 120 Rise Time tRISE MAX917 only, CL = 15pF Fall Time tFALL CL = 15pF Power-Up Time VREF Reference Voltage Temperature Coefficient Reference Output Voltage Noise TA = +25°C 1.227 TA = TMIN to TMAX 1.200 TCREF en MAX UNITS µs µs 6 tON Reference Voltage TYP 17 MAX917 only Low-to-High Propagation Delay (Note 4) MIN VCC = 1.8V µs 4 µs 1.2 ms 1.245 1.263 1.290 95 V ppm/°C BW = 10Hz to 100kHz 600 BW = 10Hz to 100kHz, CREF = 1nF 215 0.1 mV/V ±0.2 mV/nA Reference Line Regulation ∆VREF/ ∆VCC 1.8V ≤ VCC ≤ 5.5V Reference Load Regulation ∆VREF/ ∆IOUT ∆IOUT = 10nA µVRMS ELECTRICAL CHARACTERISTICS—MAX919/MAX920 (VCC = +5V, VEE = 0V, VCM = 0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Supply Voltage Range SYMBOL VCC CONDITIONS Inferred from the PSRR test MIN VCC = 1.8V Supply Current ICC VCC = 5V TA = +25°C Inferred from the CMRR test Input Offset Voltage VOS -0.2V ≤ VCM ≤ (VCC + 0.2V) (Note 2) Input-Referred Hysteresis VHB -0.2V ≤ VCM ≤ (VCC + 0.2V) (Note 3) IB TA = TMIN to TMAX 0.45 TA = TMIN to TMAX VCM Input Bias Current MAX UNITS 5.5 V 0.80 µA 0.38 Input Common-Mode Voltage Range TA = +25°C TYP 1.8 TA = +25°C 1.2 VEE - 0.2 VCC + 0.2 1 TA = TMIN to TMAX 5 10 4 0.15 V mV mV 1 2 nA _______________________________________________________________________________________ 3 MAX917–MAX920 SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference ELECTRICAL CHARACTERISTICS—MAX919/MAX920 (continued) (VCC = +5V, VEE = 0V, VCM = 0V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1) PARAMETER Input Offset Current SYMBOL CONDITIONS IOS PSRR VCC = 1.8V to 5.5V Common-Mode Rejection Ratio CMRR (VEE - 0.2V) ≤ VCM ≤ (VCC + 0.2V) Output-Voltage Swing Low Output Leakage Current VCC - VOH VOL ILEAK TA = +25°C MAX919 only, VCC = 1.8V, ISOURCE = 1mA TA = +25°C VCC = 1.8V, ISINK = 1mA TA = +25°C ISC tPD- tPD+ 0.5 3 mV/V 190 400 VCC = 5V 500 200 190 400 500 55 8 VCC = 1.8V 10 VCC = 1.8V 17 VCC = 5V 22 VCC = 1.8V 30 VCC = 5V 95 VCC = 1.8V RPULLUP = 100kΩ 35 VCC = 5V RPULLUP = 100kΩ 120 tFALL CL = 15pF mV 1 µA 95 98 Fall Time 200 300 0.001 VCC = 5V MAX919 only, CL = 15pF mV 300 VCC = 1.8V tRISE pA 55 TA = TMIN to TMAX Rise Time tON mV/V TA = TMIN to TMAX MAX920 only, VO = 5.5V MAX920 only Power-Up Time 1 TA = TMIN to TMAX TA = +25°C MAX919 only Low-to-High Propagation Delay (Note 4) UNITS TA = TMIN to TMAX VCC = 5V, ISINK = 8mA Sinking, VO = VCC High-to-Low Propagation Delay (Note 4) MAX 0.1 MAX919 only, VCC = 5V, ISOURCE = 8mA Sourcing, VO = VEE Output Short-Circuit Current TYP 10 Power-Supply Rejection Ratio Output-Voltage Swing High MIN 6 mA µs µs µs 4 µs 1.2 ms Note 1: All specifications are 100% tested at TA = +25°C. Specification limits over temperature (TA = TMIN to TMAX) are guaranteed by design, not production tested. Note 2: VOS is defined as the center of the hysteresis band at the input. Note 3: The hysteresis-related trip points are defined as the edges of the hysteresis band, measured with respect to the center of the band (i.e., VOS) (Figure 2). Note 4: Specified with an input overdrive (VOVERDRIVE) of 100mV, and load capacitance of CL = 15pF. VOVERDRIVE is defined above and beyond the offset voltage and hysteresis of the comparator input. For the MAX917/MAX918, reference voltage error should also be added. 4 _______________________________________________________________________________________ SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference TA = +25°C 700 TA = -40°C 600 MAX917-920 toc02 800 600 MAX917/MAX918 SUPPLY CURRENT vs. TEMPERATURE TA = +85°C 500 TA = +25°C 400 900 850 SUPPLY CURRENT (nA) SUPPLY CURRENT (nA) TA = +85°C SUPPLY CURRENT (nA) MAX917-920 toc01 900 MAX919/MAX920 SUPPLY CURRENT vs. SUPPLY VOLTAGE AND TEMPERATURE MAX917-920 toc03 MAX917/MAX918 SUPPLY CURRENT vs. SUPPLY VOLTAGE AND TEMPERATURE VCC = 5V 800 750 VCC = 3V 700 650 VCC = 1.8V 600 TA = -40°C 550 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 1.5 5.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 -40 5.5 10 35 60 SUPPLY VOLTAGE (V) TEMPERATURE (°C) MAX919/MAX920 SUPPLY CURRENT vs. TEMPERATURE MAX917/MAX918 SUPPLY CURRENT vs. OUTPUT TRANSITION FREQUENCY MAX919/MAX920 SUPPLY CURRENT vs. OUTPUT TRANSITION FREQUENCY VCC = 3V 400 VCC = 1.8V 10 VCC = 3V 8 6 VCC = 1.8V -15 10 35 60 85 8 6 VCC = 3V 4 1 10 100 1k 10k VCC = 1.8V 0 0 -40 10 2 2 300 VCC = 5V 12 4 350 MAX917-920 toc06 12 85 14 SUPPLY CURRENT (µA) 450 VCC = 5V 14 SUPPLY CURRENT (µA) VCC = 5V MAX917-920 toc05 16 MAX917-920 toc04 500 1 100k 10 100 1k 10k 100k OUTPUT TRANSITION FREQUENCY (Hz) OUTPUT TRANSITION FREQUENCY (Hz) OUTPUT-VOLTAGE LOW vs. SINK CURRENT OUTPUT-VOLTAGE LOW vs. SINK CURRENT AND TEMPERATURE MAX917/MAX919 OUTPUT-VOLTAGE HIGH vs. SOURCE CURRENT 350 500 VCC = 5V 400 VOL (mV) 300 250 200 150 TA = +25°C 300 TA = +85°C VCC = 1.8V 0.5 VCC = 3V VCC - VOH (V) VCC = 3V 0.6 MAX917-920 toc08 400 600 MAX917-920 toc07 VCC = 1.8V VCC = 5V MAX917-920 toc09 TEMPERATURE (°C) 450 VOL (mV) -15 SUPPLY VOLTAGE (V) 550 SUPPLY CURRENT (nA) 500 300 500 0.4 0.3 0.2 200 TA = -40°C 100 0.1 100 50 0 0 0 2 4 6 8 10 SINK CURRENT (mA) 12 14 16 0 0 2 4 6 8 10 SINK CURRENT (mA) 12 14 16 0 2 4 6 8 10 12 14 16 18 20 SOURCE CURRENT (mA) _______________________________________________________________________________________ 5 MAX917–MAX920 Typical Operating Characteristics (VCC = +5V, VEE = 0V, CL = 15pF, VOVERDRIVE = 100mV, TA = +25°C, unless otherwise noted.) Typical Operating Characteristics (continued) (VCC = +5V, VEE = 0V, CL = 15pF, VOVERDRIVE = 100mV, TA = +25°C, unless otherwise noted.) TA = +25°C TA = +85°C 0.3 0.2 TA = -40°C 0.1 80 60 VCC = 3V 40 4 6 8 -40 10 12 14 16 18 20 60 VCC = 3V 40 0 -15 10 35 60 85 VCC = 1.8V -40 -15 10 35 60 85 SOURCE CURRENT (mA) TEMPERATURE (°C) OFFSET VOLTAGE vs. TEMPERATURE HYSTERESIS VOLTAGE vs. TEMPERATURE MAX917/MAX918 REFERENCE VOLTAGE vs. TEMPERATURE VHB (mV) 0.07 VCC = 3V 0.06 4.0 3.5 0.05 VCC = 5V 3.0 0.04 MAX917-920 toc15 4.5 0.08 1.246 REFERENCE VOLTAGE (V) MAX917-920 toc14 5.0 MAX917-920 toc13 VCC = 1.8V 0.09 1.245 VCC = 3V 1.244 VCC = 1.8V 1.243 1.242 VCC = 5V -15 10 35 60 2.5 -40 85 -15 10 35 60 1.241 -40 85 -15 10 35 60 85 TEMPERATURE (°C) TEMPERATURE (°C) TEMPERATURE (°C) MAX917/MAX918 REFERENCE VOLTAGE vs. SUPPLY VOLTAGE MAX917/MAX918 REFERENCE OUTPUT VOLTAGE vs. REFERENCE SOURCE CURRENT MAX917/MAX918 REFERENCE OUTPUT VOLTAGE vs. REFERENCE SINK CURRENT VCC = 3V 1.2435 VREF (V) 1.2455 1.2450 VCC = 1.8V 1.2430 VCC = 5V 1.2425 1.2460 MAX917-920 toc17 1.2440 MAX917-920 toc16 1.2460 VCC = 1.8V 1.2455 VREF (V) 0.03 -40 MAX917-920 toc18 VOS (mV) 80 TEMPERATURE (°C) 0.10 1.2450 VCC = 3V 1.2445 VCC = 5V 1.2445 1.2440 1.5 1.2420 1.2440 1.2415 2.0 2.5 3.0 3.5 4.0 4.5 SUPPLY VOLTAGE (V) 6 VCC = 5V 100 20 VCC = 1.8V 0 2 120 20 0 0 MAX917-920 toc11 100 140 SOURCE CURRENT (mA) 0.4 VCC = 5V SINK CURRENT (mA) 0.5 VCC - VOH (V) 120 MAX917-920 toc10 0.6 MAX917/MAX919 SHORT-CIRCUIT SOURCE CURRENT vs. TEMPERATURE SHORT-CIRCUIT SINK CURRENT vs. TEMPERATURE MAX917-920 toc12 MAX917/MAX919 OUTPUT-VOLTAGE HIGH vs. SOURCE CURRENT AND TEMPERATURE REFERENCE VOLTAGE (V) MAX917–MAX920 SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference 5.0 5.5 1.2435 0 1 2 3 4 5 6 7 SOURCE CURRENT (nA) 8 9 10 0 1 2 3 4 5 6 7 SINK CURRENT (nA) _______________________________________________________________________________________ 8 9 10 SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference MAX917/MAX919 PROPAGATION DELAY (tPD+) vs. TEMPERATURE tPD+ (µs) VCC = 3V 10 VCC = 3V 60 VCC = 1.8V 20 -15 10 35 60 85 -40 60 85 0.1 1 10 100 CAPACITIVE LOAD (nF) MAX917/MAX919 PROPAGATION DELAY (tPD+) vs. CAPACITIVE LOAD PROPAGATION DELAY (tPD-) vs. INPUT OVERDRIVE MAX917/MAX919 PROPAGATION DELAY (tPD+) vs. INPUT OVERDRIVE VCC = 3V 100 MAX917-920 toc23 70 MAX917-920 toc22 120 VCC = 1.8V 60 90 1000 VCC = 5V 80 70 VCC = 5V VCC = 3V tPD+ (µs) tPD- (µs) 50 80 40 VCC = 1.8V 60 VCC = 3V 50 40 30 30 VCC = 5V 40 20 35 TEMPERATURE (°C) 140 60 10 TEMPERATURE (°C) 160 100 -15 VCC = 5V 0 0.01 0 -40 VCC = 3V 60 40 20 0 tPD+ (µs) 80 80 40 5 VCC = 1.8V 20 20 10 0 10 0.1 1 10 100 1000 0 10 20 30 40 0 50 10 20 30 40 CAPACITIVE LOAD (nF) INPUT OVERDRIVE (mV) INPUT OVERDRIVE (mV) MAX918/MAX920 PROPAGATION DELAY (tPD-) vs. PULLUP RESISTANCE MAX918/MAX920 PROPAGATION DELAY (tPD+) vs. PULLUP RESISTANCE PROPAGATION DELAY (tPD-) (VCC = 5V) VCC = 1.8V 19 18 200 tPD- (µs) VCC = 3V 17 150 IN+ (50mV/ div) VCC = 5V 100 OUT (2V/div) VCC = 3V 16 50 VCC = 5V 15 50 MAX917-920 toc27 250 MAX917-920 toc25 20 MAX917-920 toc26 0 0.01 tPD- (µs) VCC = 1.8V 100 MAX917-920 toc24 15 VCC = 5V 100 VCC = 5V 20 tPD- (µs) 120 MAX917-920 toc21 VCC = 1.8V 120 tPD- (µs) 25 140 MAX917-920 toc19 30 PROPAGATION DELAY (tPD-) vs. CAPACITIVE LOAD MAX917-920 toc20 PROPAGATION DELAY (tPD-) vs. TEMPERATURE MAX917–MAX920 Typical Operating Characteristics (continued) (VCC = +5V, VEE = 0V, CL = 15pF, VOVERDRIVE = 100mV, TA = +25°C, unless otherwise noted.) VCC = 1.8V 0 14 10 100 1k RPULLUP (kΩ) 10k 10 100 1k 10k 20µs/div RPULLUP (kΩ) _______________________________________________________________________________________ 7 MAX917–MAX920 SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference Typical Operating Characteristics (continued) (VCC = +5V, VEE = 0V, CL = 15pF, VOVERDRIVE = 100mV, TA = +25°C, unless otherwise noted.) MAX917/MAX919 PROPAGATION DELAY (tPD+) (VCC = 5V) MAX917-920 toc29 MAX917-920 toc28 MAX917-920 toc30 IN+ (50mV/ div) IN+ (50mV/ div) OUT (2V/div) IN+ (50mV/ div) OUT (2V/div) OUT (2V/div) 20µs/div 20µs/div 20µs/div PROPAGATION DELAY (tPD-) (VCC = 1.8V) MAX917/MAX919 PROPAGATION DELAY (tPD+) (VCC = 1.8V) MAX917/MAX919 10kHz RESPONSE (VCC = 1.8V) MAX917-920 toc31 MAX917-920 toc32 MAX917-920 toc33 IN+ (50mV/ div) IN+ (50mV/ div) IN+ (50mV/ div) OUT (1V/div) OUT (1V/div) OUT (1V/div) 20µs/div 20µs/div 20µs/div MAX917/MAX919 1kHz RESPONSE (VCC = 5V) POWER-UP/DOWN RESPONSE MAX917-920 toc34 200µs/div 8 MAX917/MAX919 PROPAGATION DELAY (tPD+) (VCC = 3V) PROPAGATION DELAY (tPD-) (VCC = 3V) MAX917-920 toc35 IN+ (50mV/div) VCC (2V/div) OUT (2V/div) OUT (2V/div) 40µs/div _______________________________________________________________________________________ SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference VCC VCC IN+ IN+ OUT OUT REF IN- MAX919 MAX920 MAX917 MAX918 REF 1.245V VEE VEE Pin Description PIN MAX917/MAX918 MAX919/MAX920 NAME FUNCTION SOT23-5 SO SOT23-5 SO 1 6 1 6 OUT Comparator Output 2 4 2 4 VEE Negative Supply Voltage 3 3 3 3 IN+ Comparator Noninverting Input — — 4 2 IN- Comparator Inverting Input 4 2 — — REF 1.245V Reference Output and Comparator Inverting Input 5 7 5 7 VCC Positive Supply Voltage — 1, 5, 8 — 1, 5, 8 N.C. No Connection. Not internally connected. Detailed Description The MAX917/MAX918 feature an on-board 1.245V ±1.5% reference, yet draw an ultra-low supply current of 750nA. The MAX919/MAX920 (without reference) consume just 380nA of supply current. All four devices are guaranteed to operate down to +1.8V. Their common-mode input voltage range extends 200mV beyond-the-rails. Internal hysteresis ensures clean output switching, even with slow-moving input signals. Large internal output drivers allow rail-to-rail output swing with up to ±8mA loads. The output stage employs a unique design that minimizes supply-current surges while switching, virtually eliminating the supply glitches typical of many other comparators. The MAX917/MAX919 have a push-pull output stage that sinks as well as sources current. The MAX918/MAX920 have an open-drain output stage that can be pulled beyond VCC to an absolute maximum of 6V above VEE. These open-drain versions are ideal for implementing wire-ORed output logic functions. Input Stage Circuitry The input common-mode voltage range extends from VEE - 0.2V to VCC + 0.2V. These comparators operate at any differential input voltage within these limits. Input bias current is typically ±0.15nA if the input voltage is between the supply rails. Comparator inputs are protected from overvoltage by internal ESD protection diodes connected to the supply rails. As the input voltage exceeds the supply rails, these ESD protection diodes become forward biased and begin to conduct. _______________________________________________________________________________________ 9 MAX917–MAX920 Functional Diagrams MAX917–MAX920 SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference Output Stage Circuitry The MAX917–MAX920 contain a unique break-beforemake output stage capable of rail-to-rail operation with up to ±8mA loads. Many comparators consume orders of magnitude more current during switching than during steady-state operation. However, with this family of comparators, the supply-current change during an output transition is extremely small. In the Typical Operating Characteristics, the Supply Current vs. Output Transition Frequency graphs show the minimal supplycurrent increase as the output switching frequency approaches 1kHz. This characteristic reduces the need for power-supply filter capacitors to reduce glitches created by comparator switching currents. In batterypowered applications, this characteristic results in a substantial increase in battery life. VCC 120nA REF VEE Figure 1. MAX917/MAX918 Voltage Reference Output Equivalent Circuit Reference (MAX917/MAX918) The internal reference in the MAX917/MAX918 has an output voltage of +1.245V with respect to VEE. Its typical temperature coefficient is 95ppm/°C over the full -40°C to +85°C temperature range. The reference is a PNP emitter-follower driven by a 120nA current source (Figure 1). The output impedance of the voltage reference is typically 200kΩ, preventing the reference from driving large loads. The reference can be bypassed with a low-leakage capacitor. The reference is stable for any capacitive load. For applications requiring a lower output impedance, buffer the reference with a low-input-leakage op amp, such as the MAX406. Applications Information Low-Voltage, Low-Power Operation The MAX917–MAX920 are ideally suited for use with most battery-powered systems. Table 1 lists a variety of battery types, capacities, and approximate operating times for the MAX917–MAX920, assuming nominal conditions. Internal Hysteresis Many comparators oscillate in the linear region of operation because of noise or undesired parasitic feedback. This tends to occur when the voltage on one input is equal or very close to the voltage on the other input. The MAX917–MAX920 have internal hysteresis to counter parasitic effects and noise. The hysteresis in a comparator creates two trip points: one for the rising input voltage (VTHR) and one for the falling input voltage (VTHF) (Figure 2). The difference between the trip points is the hysteresis (VHB). When the comparator’s input voltages are equal, the hysteresis effectively causes one comparator input to move quickly past the other, thus taking the input out of the region where oscillation occurs. Figure 2 illustrates the case in which IN- has a fixed voltage applied, and IN+ is varied. If the inputs were reversed, the figure would be the same, except with an inverted output. Table 1. Battery Applications Using MAX917–MAX920 BATTERY TYPE RECHARGEABLE VFRESH (V) VEND-OF-LIFE (V) CAPACITY, AA SIZE (mA-h) MAX917/MAX918 OPERATING TIME (hr) MAX919/MAX920 OPERATING TIME (hr) Alkaline (2 Cells) No 3.0 1.8 2000 2.5 x 106 5 x 106 Nickel-Cadmium (2 Cells) Yes 2.4 1.8 750 937,500 1.875 x 106 Lithium-Ion (1 Cell) Yes 3.5 2.7 1000 1.25 x 106 2.5 x 106 Nickel-MetalHydride (2 Cells) Yes 2.4 1.8 1000 1.25 x 106 2.5 x 106 10 ______________________________________________________________________________________ SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference MAX917–MAX920 VCC THRESHOLDS IN+ R3 VTHR R1 HYSTERESIS INVHB VIN VCC BAND R2 OUT VEE VTHF MAX917 MAX919 VREF OUT Figure 2. Threshold Hysteresis Band Additional Hysteresis (MAX917/MAX919) The MAX917/MAX919 have a 4mV internal hysteresis band (VHB). Additional hysteresis can be generated with three resistors using positive feedback (Figure 3). Unfortunately, this method also slows hysteresis response time. Use the following procedure to calculate resistor values. 1) Select R3. Leakage current at IN is under 2nA, so the current through R3 should be at least 0.2µA to minimize errors caused by leakage current. The current through R3 at the trip point is (VREF - VOUT)/R3. Considering the two possible output states in solving for R3 yields two formulas: R3 = VREF/IR3 or R3 = (VCC - VREF)/IR3. Use the smaller of the two resulting resistor values. For example, when using the MAX917 (VREF = 1.245V) and VCC = 5V, and if we choose IR3 = 1µA, then the two resistor values are 1.2MΩ and 3.8MΩ. Choose a 1.2MΩ standard value for R3. 2) Choose the hysteresis band required (VHB). For this example, choose 50mV. 3) Calculate R1 according to the following equation: R1 = R3 (VHB / VCC) For this example, insert the values R1 = 1.2MΩ (50mV/5V) = 12kΩ 4) Choose the trip point for VIN rising (VTHR) such that VTHR > VREF · (R1 + R3)/R3 (VTHF is the trip point for VIN falling). This is the threshold voltage at which the comparator switches its output from low to high as V IN rises above the trip point. For this example, choose 3V. 5) Calculate R2 as follows: R2 = 1/[VTHR/(VREF · R1) - (1 / R1) - (1 / R3)] Figure 3. MAX917/MAX919 Additional Hysteresis R2 = 1/[3.0V/(1.2V · 12kΩ) - (1 / 12kΩ) (1/1.2MΩ)] = 8.05kΩ For this example, choose an 8.2kΩ standard value. 6) Verify the trip voltages and hysteresis as follows: VIN rising: VTHR = VREF · R1 [(1 / R1) + (1 / R2) + (1 / R3)] VIN falling: VTHF = VTHR - (R1 · VCC / R3) Hysteresis = VTHR - VTHF Additional Hysteresis (MAX918/MAX920) The MAX918/MAX920 have a 4mV internal hysteresis band. They have open-drain outputs and require an external pullup resistor (Figure 4). Additional hysteresis can be generated using positive feedback, but the formulas differ slightly from those of the MAX917/ MAX919. Use the following procedure to calculate resistor values. 1) Select R3 according to the formulas R3 = VREF / 1µA or R3 = (VCC - VREF)/1µA - R4. Use the smaller of the two resulting resistor values. 2) Choose the hysteresis band required (VHB). 3) Calculate R1 according to the following equation: R1 = (R3 + R4) (VHB/VCC) 4) Choose the trip point for VIN rising (VTHR) (VTHF is the trip point for VIN falling). This is the threshold voltage at which the comparator switches its output from low to high as VIN rises above the trip point. 5) Calculate R2 as follows: ⎡ ⎛ 1⎞ 1 ⎤ ⎥ R2 = 1/ ⎢VTHR / VREF ⋅ R1 − ⎜ ⎟ − ⎢ ⎥ R1 R3 ⎝ ⎠ ⎦ ⎣ ( ) ______________________________________________________________________________________ 11 MAX917–MAX920 SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference 6) Verify the trip voltages and hysteresis as follows: 1 1⎞ ⎛ 1 VIN rising : VTHR = VREF × R1 ⎜ + + ⎟ ⎝ R1 R2 R3 ⎠ VIN falling : VTHF = 1 1 ⎞ R1 ⎛ 1 VREF × R1 ⎜ + + × VCC ⎟− ⎝ R1 R2 R3 + R4 ⎠ R3 + R4 Hysteresis = VTHR - VTHF Board Layout and Bypassing Power-supply bypass capacitors are not typically needed, but use 100nF bypass capacitors close to the device’s supply pins when supply impedance is high, supply leads are long, or excessive noise is expected on the supply lines. Minimize signal trace lengths to reduce stray capacitance. A ground plane and surface-mount components are recommended. VCC Zero-Crossing Detector Figure 5 shows a zero-crossing detector application. The MAX919’s inverting input is connected to ground, and its noninverting input is connected to a 100mVP-P signal source. As the signal at the noninverting input crosses 0V, the comparator’s output changes state. Logic-Level Translator The Typical Application Circuit shows an application that converts 5V logic to 3V logic levels. The MAX920 is powered by the +5V supply voltage, and the pullup resistor for the MAX920’s open-drain output is connected to the +3V supply voltage. This configuration allows the full 5V logic swing without creating overvoltage on the 3V logic inputs. For 3V to 5V logic-level translations, simply connect the +3V supply voltage to VCC and the +5V supply voltage to the pullup resistor. VCC VCC 100mVP-P IN+ R3 OUT R1 R4 VIN VCC R2 IN- OUT MAX919 VEE VREF VEE MAX918 MAX920 Figure 5. Zero-Crossing Detector Typical Application Circuit Figure 4. MAX918/MAX920 Additional Hysteresis +5V (+3V) Pin Configurations (continued) +3V (+5V) TOP VIEW 100kΩ N.C. 1 8 N.C. 7 VCC 6 OUT 5 N.C. VCC RPULLUP INOUT IN- (REF) 2 IN+ 3 MAX917 MAX918 MAX919 MAX920 VEE 4 100kΩ IN+ MAX920 VEE SO ( ) ARE FOR MAX917/MAX918. 12 5V (3V) LOGIC IN LOGIC-LEVEL TRANSLATOR ______________________________________________________________________________________ 3V (5V) LOGIC OUT SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference SOT-23 5L .EPS ______________________________________________________________________________________ 13 MAX917–MAX920 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.) DIM A A1 B C e E H L N E H INCHES MILLIMETERS MAX MIN 0.069 0.053 0.010 0.004 0.014 0.019 0.007 0.010 0.050 BSC 0.150 0.157 0.228 0.244 0.016 0.050 MAX MIN 1.35 1.75 0.10 0.25 0.35 0.49 0.19 0.25 1.27 BSC 3.80 4.00 5.80 6.20 0.40 SOICN .EPS MAX917–MAX920 SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference 1.27 VARIATIONS: 1 INCHES TOP VIEW DIM D D D MIN 0.189 0.337 0.386 MAX 0.197 0.344 0.394 MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC D A B e C 0∞-8∞ A1 L FRONT VIEW SIDE VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, .150" SOIC APPROVAL DOCUMENT CONTROL NO. 21-0041 14 ______________________________________________________________________________________ REV. B 1 1 SOT23, 1.8V, Nanopower, Beyond-the-Rails Comparators With/Without Reference SOT-23 5L .EPS Revision History Pages changed at Rev 1: 1–15 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 ____________________ 15 © 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc. MAX917–MAX920 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.)