19-1226; Rev 0; 4/97 Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators ____________________________Features ♦ Ultra-Low Single-Supply Operation down to +1.6V A +1.6V to +5.5V single-supply operating voltage range makes the MAX965 family of comparators ideal for 2-cell battery-powered applications. The MAX965/MAX967/ MAX968/MAX969 offer programmable hysteresis and an internal 1.235V ±1.5% reference. All devices are available in either space-saving 8-pin µMAX or 16-pin QSOP packages. ♦ Rail-to-Rail Common-Mode Input Voltage Range ♦ 3µA Quiescent Supply Current per Comparator ♦ Open-Drain Outputs Swing Beyond VCC ♦ 1.235V ±1.5% Precision Internal Reference (MAX965/967/968/969) ♦ 10µs Propagation Delay (50mV overdrive) ♦ Available in Space-Saving Packages: 8-Pin µMAX (MAX965–MAX968) 16-Pin QSOP (MAX969/MAX970) ________________________Applications 2-Cell Battery-Powered/Portable Systems Window Comparators Threshold Detectors/Discriminators Mobile Communications Voltage-Level Translation Ground/Supply-Sensing Applications PART INTERNAL REFERENCE COMPARATORS PER PACKAGE PROGRAMMABLE HYSTERESIS _____________________Selector Guide MAX965 Yes 1 Yes MAX966 No 2 No MAX967 Yes 2 Yes MAX968 Yes 2 Yes MAX969 Yes 4 Yes MAX970 No 4 No ______________Ordering Information TEMP. RANGE PIN-PACKAGE MAX965ESA PART -40°C to +85°C 8 SO MAX965EUA MAX966ESA MAX966EUA MAX967ESA MAX967EUA -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C 8 µMAX 8 SO 8 µMAX 8 SO 8 µMAX Ordering Information continued on last page. Pin Configurations appear at end of data sheet. __________Typical Operating Circuit VIN VCC 7 VCC 3 IN+ RPULL-UP OUT 8 VOUT 4 IN5 HYST 6 REF MAX965 1.235V GND Rail-to-Rail is a registered trademark of Nippon Motorola Ltd. 1 ________________________________________________________________ Maxim Integrated Products 1 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 MAX965–MAX970 _______________General Description The MAX965–MAX970 single/dual/quad micropower comparators feature Rail-to-Rail® inputs and outputs, and fully specified single-supply operation down to +1.6V. These devices draw less than 5µA per comparator and have open-drain outputs that can be pulled beyond VCC to 6V (max) above ground. In addition, their rail-to-rail input common-mode voltage range makes these comparators suitable for ultra-low-voltage operation. MAX965–MAX970 Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators ABSOLUTE MAXIMUM RATINGS Supply Voltage (VCC) ............................................................+6V Voltages IN_-, IN_+, REF, HYST ..........................-0.3V to (VCC + 0.3V) OUT_ ...............................................................-0.3V to +6.0V Duration of OUT_ Short Circuit to GND or VCC ..........Continuous Continuous Power Dissipation 8-Pin SO (derate 5.88mW/°C above +70°C)...............471mW 8-Pin µMAX (derate 4.10mW/°C above +70°C) ..........330mW 14-Pin SO (derate 8.33mW/°C above +70°C).............667mW 16-Pin SO (derate 8.70mW/°C above +70°C).............696mW 16-Pin QSOP (derate 5.70mW/°C above +70°C)........457mW 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 (VCC = +1.6V to +5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 3V and TA = +25°C.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS POWER SUPPLIES Supply Voltage Range VCC All packages, TA = 0°C to +85°C 1.6 5.5 SO/QSOP packages, TA = -40°C to +85°C 1.7 5.5 µMAX package, TA = -40°C to +85°C 1.8 5.5 Comparator Minimum Operating Voltage Supply Current 1.0 ICC Power-Up Time (VCC to output valid) V V MAX965 7.0 12 MAX966 6.0 10 MAX967/MAX968 10 16 MAX969 14 22 MAX970 11 18 VCC stepped 0V to 5V 20 1.7V ≤ VCC ≤ 5.5V 0.1 µA µs COMPARATOR Power-Supply Rejection Ratio PSRR Common-Mode Voltage Range VCMR Input Offset Voltage VOS TA = +25°C TA = -40°C to +85°C SO package Common-mode QSOP package range = -0.25V to 1.3V, 0°C to +85°C µMAX VCC > 1.8V package -40°C to +85°C Full commonmode range Input Hysteresis Input Bias Current VHYST IB -0.25 -0.25 1.0 VCC VCC - 0.25 3.0 4.0 6.0 7.0 QSOP package 10.0 0°C to +85°C mV 10.0 -40°C to +85°C HYST = REF V V 4.0 SO package µMAX package mV/V 15.0 ±1 mV Common-mode range = -0.25V to (VCC - 0.25V) 0.001 ±5 Full common-mode range, TA = +25°C 0.001 ±50 nA Input Offset Current IOS 0.2 pA Input Capacitance CIN 7.0 pF 2 _______________________________________________________________________________________ Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators MAX965–MAX970 ELECTRICAL CHARACTERISTICS (continued) (VCC = +1.6V to +5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 3V and TA = +25°C.) PARAMETER SYMBOL Common-Mode Rejection Ratio CMRR CONDITIONS MIN TYP MAX UNITS 1.5 4.0 mV/V VREF V ±5 nA VREF 0.05 HYST Input Voltage Range HYST Input Leakage IHYST Hysteresis Gain Input Voltage Noise en f = 100Hz to 100kHz, CREF = 1000pF 1.0 V/V 10 µVRMS IOUT = 100µA, 1.6V < VCC < 2.7V 0.2 IOUT = 500µA, 2.7V < VCC < 5.5V 0.4 OUT Output Voltage Low VOL Propagation Delay tPD- RPULL-UP = 1MΩ, CLOAD = 15pF, high to low Reference Voltage VREF SO package QSOP package µMAX package, TA = 0°C to +85°C µMAX package, TA = -40°C to +85°C Source Current IREF+ HYST = REF Sink Current IREF- 10mV overdrive 20 50mV overdrive 10 V µs REFERENCE Output Voltage Noise 1.125 1.205 1.205 1.185 1.235 1.235 1.235 1.235 15 50 200 400 nA 10 µVRMS f = 100Hz to 100kHz, CREF = 0.1µF 1.255 1.265 1.265 1.285 V V µA __________________________________________Typical Operating Characteristics (VCC = +3.0V, RPULL-UP = 100kΩ, VCM = 0V, TA = +25°C, unless otherwise noted.) MAX966 SUPPLY CURRENT vs. TEMPERATURE 10 9 8 VCC = 3.0V 7 6 5 -40 -20 0 7.0 VCC = 5.0V 6.5 6.0 VCC = 3.0V 5.5 20 40 TEMPERATURE (°C) 60 80 13 12 VCC = 5.0V 11 10 VCC = 3.0V 9 8 VCC = 2.0V 6 VIN+ > VIN- 4.0 100 14 7 VCC = 2.0V 4.5 VIN+ > VIN- 3 -60 7.5 5.0 VCC = 2.0V 4 8.0 SUPPLY CURRENT (µA) VCC = 5.0V 8.5 SUPPLY CURRENT (µA) 11 15 MAX965-TOC2b 12 SUPPLY CURRENT (µA) 9.0 MAX965-TOC1b 13 MAX967/MAX968 SUPPLY CURRENT vs. TEMPERATURE MAX965-TOC3b MAX965 SUPPLY CURRENT vs. TEMPERATURE VIN+ > VIN- 5 -60 -40 -20 0 20 40 TEMPERATURE (°C) 60 80 100 -60 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) _______________________________________________________________________________________ 3 _____________________________Typical Operating Characteristics (continued) (VCC = +3.0V, RPULL-UP = 100kΩ, VCM = 0V, TA = +25°C, unless otherwise noted.) MAX969 SUPPLY CURRENT vs. TEMPERATURE 14 VCC = 3.0V VCC = 5.0V 12 11 VCC = 3.0V 10 VCC = 2.0V 9 10 VCC = 2.0V 8 VIN+ > VIN- 8 VIN+ > VIN- 2.0 1.5 1.0 0.5 VIN+ > VIN0 0 20 40 60 80 100 -60 -40 -20 MAX965/70-TOC7a 14 12 10 8 6 4 2 VIN+ > VIN- OUTPUT SHORT-CIRCUIT SINK CURRENT (mA) MAX965 SUPPLY CURRENT vs. SUPPLY VOLTAGE (INCLUDES REFERENCE CURRENT) 0 20 40 60 80 0 100 1 2 3 4 5 4 5 COMPARATOR OUTPUT LOW VOLTAGE vs. SINK CURRENT 14 VIN+ < VIN- 12 VCC = 5V 10 8 6 VCC = 3V 4 5.0 VIN+ = < VIN- 4.5 4.0 3.5 3.0 2.5 VCC = 2V VCC = 3V 2.0 1.5 VCC = 5V 0.5 0 -60 -40 -20 0 20 40 60 80 0 100 2 4 6 8 10 SUPPLY VOLTAGE (V) TEMPERATURE (°C) SINK CURRENT (mA) PROPAGATION DELAY (tPD-) vs. TEMPERATURE PROPAGATION DELAY (tPD-) vs. CAPACITIVE LOAD PROPAGATION DELAY (tPD-) vs. INPUT OVERDRIVE VCC = 2.0V VOD = 50mV 30 60 25 50 VCC = 3.0V VCC = 5.0V 8 7 20 DELAY (µs) 10 DELAY (µs) 11 12 MAX965-TOC12a 12 70 MAX965-TOC10a 13 6 1.0 VCC = 2V 2 6 14 9 3 COMPARATOR OUTPUT SHORT-CIRCUIT SINK CURRENT vs. TEMPERATURE MAX4108/9-11a 0 2 SUPPLY VOLTAGE (V) 0 0 1 TEMPERATURE (°C) OUTPUT LOW VOLTAGE (V) -20 MAX965/70 -TOC8a -40 TEMPERATURE (°C) SUPPLY CURRENT (µA) 2.5 7 -60 VCC = 2.0V 40 30 VCC = 3.0V 15 VCC = 2.0V VCC = 3.0V 10 20 6 VOD = 50mV 4 VCC = 5.0V 0 0 -60 -40 -20 0 20 40 TEMPERATURE (°C) 60 80 100 VCC = 5.0V 5 10 5 4 3.0 MAX965/70-09a VCC = 5.0V 14 13 MAX965-TOC6b 15 3.5 SUPPLY CURRENT PER COMPARATOR (µA) 16 MAX965-TOC5b MAX965-TOC4b 16 SUPPLY CURRENT (µA) SUPPLY CURRENT (µA) 18 12 SUPPLY CURRENT PER COMPARATOR vs. SUPPLY VOLTAGE (EXCLUDES REFERENCE CURRENT) MAX970 SUPPLY CURRENT vs. TEMPERATURE 20 DELAY (µs) MAX965–MAX970 Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators 0.001 0.01 CAPACITIVE LOAD (µF) 0.1 0 20 40 60 80 100 120 140 160 INPUT OVERDRIVE (mV) _______________________________________________________________________________________ Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators MAX965–MAX970 _____________________________Typical Operating Characteristics (continued) (VCC = +3.0V, RPULL-UP = 100kΩ, VCM = 0V, TA = +25°C, unless otherwise noted.) 3.4 3.2 VCC = 5.5V 2.8 2.6 VCC = 1.6V 180 170 160 150 140 130 2.0 1.5 1.0 100 -60 -40 -20 60 80 -40 100 25 20 VCC = 5V 1.2340 1.2330 15 10 VCC = 2V 1.2325 VCC = 5.0V VHYST = 22mV (PROGRAMMED) 1.2320 -40 -20 MAX965/70-TOC18a 1.2 100 1.235 1.233 1.231 1.229 1.227 0 20 40 60 80 100 1.0 1.8 2.6 3.4 4.2 5.0 5.8 VCC (V) PROPAGATION DELAY (tPD-) MAX965/70-TOC15 1.3 80 1.237 PROPAGATION DELAY (tPD+) 1.4 60 1.239 TEMPERATURE (°C) COMMON-MODE VOLTAGE (V) REFERENCE VOLTAGE vs. SOURCE CURRENT 40 1.223 -60 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 20 1.225 VCC = 3V 0 0 0 REFERENCE VOLTAGE vs. SUPPLY VOLTAGE 1.2335 5 -20 TEMPERATURE (°C) 1.2345 REFERENCE VOLTAGE (V) 30 40 REFERENCE VOLTAGE vs. TEMPERATURE MAX965/70 TOC16 35 20 TEMPERATURE (°C) PROGRAMMED HYSTERESIS vs. COMMON-MODE VOLTAGE 40 0 REFERENCE VOLTAGE (V) 10 MAX965/70 TOC6a 1 VCC = 3.0V 0 100 0.1 OUTPUT TRANSITION FREQUENCY (kHz) PROGRAMMED HYSTERESIS (mV) 2.5 0.5 110 2.0 REFERENCE VOLTAGE (V) 3.0 120 2.2 0.01 VCC = 5.0V 3.5 MAX965/70-TOC13 2.4 190 INPUT BIAS CURRENT (pA) 3.6 4.0 MAX965/70-TOC14a MAX965/70 TOC13A 3.8 200 INPUT OFFSET VOLTAGE (µV) SUPPLY CURRENT PER COMPARATOR (µA) 4.0 3.0 INPUT BIAS CURRENT vs. TEMPERATURE INPUT OFFSET VOLTAGE vs. TEMPERATURE MAX965/70-TOC15a SUPPLY CURRENT PER COMPARATOR vs. OUTPUT TRANSITION FREQUENCY MAX965/70-TOC16b VCC = 3V VCC = 3V IN+ 50mV/div IN+ 50mV/div 1.1 1.0 0.9 0.8 OUT 2V/div OUT 2V/div 0.7 0.6 0 100 200 300 400 500 600 700 2µs/div 2µs/div SOURCE CURRENT (µA) _______________________________________________________________________________________ 5 MAX965–MAX970 Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators _____________________________Typical Operating Characteristics (continued) (VCC = +3.0V, RPULL-UP = 100kΩ, VCM = 0V, TA = +25°C, unless otherwise noted.) 10kHz RESPONSE POWER-UP/DOWN RESPONSE MAX965/70-TOC18 MAX965/70-TOC17 IN+ 50mV/div VCC 2V/div OUT 1V/div OUT 2V/div 20µs/div 5µs/div _____________________________________________________________Pin Descriptions MAX965–MAX968 PIN NAME FUNCTION MAX965 MAX966 MAX967 MAX968 — 1 1 1 OUTA Comparator A Open-Drain Output 1 2 2 2 GND Ground 2 — — — N.C. No Connection. Not internally connected. 3 — — — IN+ Comparator Noninverting Input — 3 3 3 INA+ 4 — — — IN- — 4 — — INA- Comparator A Inverting Input — 5 — 4 INB- Comparator B Inverting Input — 6 4 — INB+ Comparator B Noninverting Input 5 — 5 5 HYST Hysteresis Input. Connect HYST to REF if not used. Input voltage range is from VREF to (VREF - 50mV). 6 — 6 6 REF Internal Reference Output. Typically 1.235V with respect to GND. 7 7 7 7 VCC Positive Supply Voltage, +1.6V to +5.5V 8 — — — OUT Comparator Open-Drain Output — 8 8 8 OUTB 6 Comparator A Noninverting Input Comparator Inverting Input Comparator B Open-Drain Output _______________________________________________________________________________________ Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators PIN MAX970 NAME FUNCTION MAX969 SO QSOP 1 1 1 OUTB Comparator B Open-Drain Output 2 2 2 OUTA Comparator A Open-Drain Output 3 3 3 VCC Positive Supply Voltage, +1.6V to +5.5V 4 4 4 INA- Comparator A Inverting Input 5 5 5 INA+ Comparator A Noninverting Input 6 6 6 INB- Comparator B Inverting Input 7 7 7 INB+ Comparator B Noninverting Input — — 8, 9 N.C. No Connection. Not internally connected. 8 — — REF Internal Reference Output. Typically 1.235V with respect to GND. 9 — — HYST Hysteresis Input. Connect to REF if not used. Input voltage range is from (VREF - 50mV) to VREF. 10 8 10 INC- Comparator C Inverting Input 11 9 11 INC+ Comparator C Noninverting Input 12 10 12 IND- Comparator D Inverting Input 13 11 13 IND+ Comparator D Noninverting Input 14 12 14 GND Ground 15 13 15 OUTD Comparator D Open-Drain Output 16 14 16 OUTC Comparator C Open-Drain Output _______________Detailed Description The MAX965–MAX970 single/dual/quad, micropower, ultra-low-voltage comparators feature Rail-to-Rail® inputs and outputs and an internal 1.235V ±1.5% bandgap reference. These devices operate from a single +1.6V to +5.5V supply voltage range, and consume less than 5µA supply current per comparator over the extended temperature range. Internal hysteresis is programmable up to ±50mV using two external resistors and the device’s internal reference. The rail-to-rail input common-mode voltage range and the open-drain outputs allow easy voltage-level conversion for multivoltage systems. All inputs and outputs can tolerate a continuous short-circuit fault condition to either rail. The MAX965 is a single comparator with adjustable hysteresis and a reference output pin. The MAX966 is a dual comparator without the reference and without adjustable hysteresis. The MAX967 is a dual compara- tor configured as a dual voltage monitor with common hysteresis adjustment and a reference output. The dual MAX968 is similar to the MAX967, but is configured as a window comparator. The MAX969 is a quad comparator with a common hysteresis adjustment and a reference output pin. The MAX970 is a quad comparator without a reference and without hysteresis adjustment. (See Functional Diagrams and Selector Guide.) Comparator Input The MAX965–MAX970 have a -0.25V to VCC input common-mode range. Both comparator inputs may operate at any differential voltage within the common-mode voltage range, and the comparator displays the correct output logic state. Low-Voltage Operation: VCC Down to 1V The minimum operating voltage is 1.6V. As the supply voltage falls below 1.6V, performance degrades and supply current falls. The reference does not _______________________________________________________________________________________ 7 MAX965–MAX970 ________________________________________________Pin Descriptions (continued) MAX969/MAX970 MAX965–MAX970 Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators ________________________________________________________Functional Diagrams VCC VCC IN+ OUTB OUTA OUT MAX966 INHYST REF MAX965 + 1.235V REF INA+ INB+ INA- INBGND GND VCC INA+ VCC INA+ OUTA OUTA REF REF HYST HYST REF REF 1.235V 1.235V OUTB OUTB INB+ INBGND GND VCC OUTB MAX968 VCC OUTC OUTB OUTA OUTD OUTA OUTD INA- IND+ INA- IND+ INA+ IND- INA+ IND- INB- INC+ INB- INC+ INB+ INC- INB+ INC- REF + 1.235V MAX969 REF GND 8 MAX967 HYST MAX970 GND _______________________________________________________________________________________ OUTC Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators Comparator Output The MAX965–MAX970 contain a unique slew-ratecontrolled output stage capable of rail-to-rail operation with an external pull-up resistor. Typical comparators consume orders of magnitude more current during switching than during steady-state operation. With the MAX965 family of comparators, during an output transition from high to low, the output slew rate is limited to minimize switching current. Voltage Reference With VCC greater than 1.6V but less than 5.5V, the internal 1.235V bandgap reference is ±1.5% accurate over the commercial temperature range and ±2.5% accurate over the extended temperature range. The REF output is typically capable of sourcing 50µA. To reduce reference noise or to provide noise immunity, bypass REF with a capacitor (0.1nF to 0.1µF). Noise Considerations The comparator has an effective wideband peak-topeak noise of around 10µV. The voltage reference has peak-to-peak noise approaching 1.0mV with a 0.1µF bypass capacitor. Thus, when a comparator is used with the reference, the combined peak-to-peak noise is about 1.0mV. This, of course, is much higher than the individual components’ RMS noise. Avoid capacitive coupling from any output to the reference pin. Crosstalk can significantly increase the references’ actual noise. __________Applications Information 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 MAX965–MAX970 have internal hysteresis to counter parasitic effects and noise. In addition, with the use of external resistor, the MAX965/MAX967/ MAX968/MAX969’s hysteresis can be programmed to as much as ±50mV (see the section Adding Hysteresis to the MAX965/MAX967/MAX968/MAX969). The hysteresis in a comparator creates two trip points: one for the rising input voltage and one for the falling input voltage (Figure 2). The difference between the trip points is the hysteresis. When the comparator’s input voltages are equal, the hysteresis effectively causes one comparator input voltage to move quickly past the other, thus taking the input out of the region where oscillation occurs. VCC 1.6V VCC THRESHOLDS IN+ V+ 1.0V VREF R1 t 47k 100k V+ INVREF - VHYST HYSTERESIS VHB BAND VCC R2 150k OUT GND REF MAX965 Figure 1. Operation below 1.6V VTRIP = 1.22 R1 + 1 R2 V R1 = TRIP - 1 x R2 1.22 OUT Figure 2. Threshold Hysteresis Band _______________________________________________________________________________________ 9 MAX965–MAX970 function below about 1.5V, although the comparators typically continue to operate with a supply voltage as low as 1V. At low supply voltages (<1.6V), the input common-mode range remains rail-to-rail, but the comparator’s output sink capability is reduced and propagation delay increases (see Typical Operating Characteristics). Figure 1 shows a typical comparator application that monitors VCC at 1.6V. Resistor divider R1/R2 sets the voltage trip point (VTRIP) at 1.6V. As VCC drops below 1.6V and approaches 1V, the reference voltage typically falls below the divider voltage (V+). This causes the comparator output to change state. If OUT’s state must be maintained under these conditions, a latching circuit is required. MAX965–MAX970 Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators 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. Adding Hysteresis to the MAX965/MAX967/MAX968/MAX969 To add hysteresis to the MAX965/MAX967/MAX968/ MAX969, connect resistor R1 between REF and HYST, and connect resistor R2 between HYST and GND (Figure 3). If additional hysteresis is not required, connect HYST to REF. When hysteresis is added, the upper and lower trip points change by the same amount in opposite directions. The hysteresis band (the difference between the upper and lower trip points, VHB) is approximately twice the voltage between HYST and REF. The HYST input voltage range is from REF down to (REF - 50mV). This yields a hysteresis band from ±1mV to a maximum of ±50mV. Calculate the values of R1 and R2 for the desired hysteresis band with the following formulas: R1 = VHB / IREF R2 = (VREF - VHB) / IREF where IREF (the current sourced by the reference) does not exceed the REF source capability (12µA typical), and is significantly larger than the HYST leakage current (5nA typical). IREF values between 0.1µA and 4µA are good choices. If 2.4MΩ is chosen for R2 (IREF = 0.5µA), the equation for R1 and VHB can be approximated as: R1(kΩ) = 2 x VHB (mV) In the MAX967/MAX968/MAX969, the HYST pin programs the same hysteresis for all comparators in the package. Due to the internal structure of the input developed for ultra-low-voltage operation, the hysteresis band varies with common-mode voltage. The graph Programmed Hysteresis vs. Common-Mode Voltage in the Typical Operating Characteristics shows this variation. Notice that the hysteresis band increases to almost twice the calculated value toward the ends of the common-mode range. This is apparent only when programming additional hysteresis using the HYST pin. The hysteresis band is constant when HYST is connected to REF. Adding Hysteresis to the MAX966/MAX970 The MAX966/MAX970 do not have a HYST pin for programming hysteresis. Hysteresis can be generated with three resistors using positive feedback (Figure 4). This method generally draws more current than the method using the HYST pin on the MAX965/MAX967/MAX968/ MAX969. Also, the positive feedback method slows hysteresis response time. Use the following procedure to calculate the resistor values: 1) Select R3. The leakage current of IN+ is under 5nA, so the current through R3 should be at least 500nA to minimize errors caused by leakage current. The current through R3 at the trip point is (VREF - VOUT) / R3. Taking into consideration the two possible output states and solving for R3 yields two formulas: R3 = VREF / 500nA and R3 = (VREF - VCC) / 500nA Use the smaller of the two resulting resistor values. For example, if VREF = 1.2V and VCC = 5.0V, then the two resistor values are 2.4MΩ and 7.6mΩ. For R3, choose the 2.2MΩ standard value. 2) Choose the hysteresis band required (VHB). For this example, choose 50mV. VCC +1.6V TO +5.5V R3 IREF REF VCC R1 R1 HYST R2 MAX965 MAX967 MAX968 MAX969 R4 VIN VCC GND GND VREF Figure 3. Programming the HYST Pin 10 OUT R2 MAX966 MAX970 Figure 4. External Hysteresis ______________________________________________________________________________________ Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators 4) Choose the trip point for V IN rising. This is the threshold voltage where the comparator output transitions from low to high as VIN rises above the trip point. For this example, choose 3.0V. 5) Calculate R2 as follows: IR Receiver Figure 5 shows an application using the MAX965 as an infrared receiver. The infrared photodiode creates a current relative to the amount of infrared light present. This current creates a voltage across R1. When this voltage level crosses the reference voltage applied to the inverting input, the output transitions. Optional R3 provides additional hysteresis for noise immunity. 2-Cell to TTL Logic-Level Shifter R2 = R2 = 1 VTHR 1 1 − V − R3 + R4 REF x R1 R1 1 = 14.76k 3.0V 1 1 − − 22k 2.2M + 10k 1.2 x 22k Figure 6 shows an application using the MAX965 to convert a 2-cell voltage-level signal into a TTLcompatible signal. The supply voltage for the comparator comes from the 2-cell supply. The output is pulled up to a 5V supply. VCC R3 VCC where V THR is the rising-voltage trip threshold. Choose a standard value of 15kΩ. VCC 0.1µF 6) Verify trip voltages and hysteresis as follows: VIN rising : RD 1 1 1 + VTHR = VREF x R1 x + R1 R2 R3 + R4 VCC HYST GND REF OUT MAX965 VIN falling : R1 x VCC VTHF = VTHR − R3 + R4 RPULL-UP Figure 5. IR Receiver Hysteresis = VTHR − VTHF where VTHR is the rising-voltage trip point, and VTHF is the falling-voltage trip point. 2 CELLS 0.1µF +5V Circuit Layout and Bypassing Power-supply bypass capacitors are not needed if supply impedance is low, but 100nF bypass capacitors should be used when supply impedance is high or when supply leads are long. Minimize signal lead lengths to reduce stray capacitance between the input and output that might cause instability. INPUT VCC HYST GND REF OUT MAX965 Figure 6. 2-Cell to TTL Logic-Level Translator ______________________________________________________________________________________ 11 MAX965–MAX970 3) Calculate R1: R1 = (R3 + R4) x (VHB / VCC). Putting in the values for this example, R1 = (2.2MΩ + 10k) x (50mV / 5.0V) = 22.1kΩ. MAX965–MAX970 Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators __________________________________________________________Pin Configurations TOP VIEW GND 1 8 OUT N.C. 2 7 VCC IN+ 3 MAX965 IN- 4 OUTA 1 8 OUTB GND 2 7 VCC 6 REF INA+ 3 5 HYST INA- 4 SO/µMAX MAX966 OUTA 1 8 OUTB GND 2 7 VCC 6 REF 5 HYST 6 INB+ INA+ 3 5 INB- INB+ 4 (INB-) MAX967 MAX968 SO/µMAX SO/µMAX OUTB 1 16 OUTC OUTB 1 14 OUTC OUTB 1 16 OUTC OUTA 2 15 OUTD OUTA 2 13 OUTD OUTA 2 15 OUTD 14 GND VCC 3 12 GND VCC 3 14 GND VCC 3 MAX969 MAX970 13 IND+ INA- 4 INA+ 5 12 IND- INA+ 5 INB- 6 11 INC+ INB- 6 9 INB+ 7 10 INC- INB+ 7 8 INA- 4 REF 8 9 HYST MAX970 11 IND+ INA- 4 10 IND- INA+ 5 12 IND- INC+ INB- 6 11 INC+ INC- INB+ 7 10 INC- N.C. 8 9 SO SO/QSOP 13 IND+ N.C. QSOP ( ) ARE FOR MAX968 ONLY. _Ordering Information (continued) ___________________Chip Information TEMP. RANGE PIN-PACKAGE TRANSISTOR COUNTS: MAX968ESA -40°C to +85°C 8 SO MAX965 = 216 MAX968EUA MAX969ESE MAX969EEE MAX970ESD MAX970EEE -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C -40°C to +85°C 8 µMAX 16 Narrow SO 16 QSOP 14 SO 16 QSOP MAX966 = 190 PART MAX967/MAX968 = 299 MAX969 = 465 MAX970 = 380 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 © 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.