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19-1226; Rev 0; 4/97
Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
_______________General Description
The MAX965-MAX970 single/dual/quad micropower comparators feature Rail-to-Rail(R) inputs and outputs, and fully specified single-supply operation down to +1.6V. These devices draw less than 5A 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. 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 MAX or 16-pin QSOP packages.
____________________________Features
o Ultra-Low Single-Supply Operation down to +1.6V o Rail-to-Rail Common-Mode Input Voltage Range o 3A Quiescent Supply Current per Comparator o Open-Drain Outputs Swing Beyond VCC o 1.235V 1.5% Precision Internal Reference (MAX965/967/968/969) o 10s Propagation Delay (50mV overdrive) o Available in Space-Saving Packages: 8-Pin MAX (MAX965-MAX968) 16-Pin QSOP (MAX969/MAX970)
MAX965-MAX970
________________________Applications
2-Cell Battery-Powered/Portable Systems Window Comparators Threshold Detectors/Discriminators Mobile Communications Voltage-Level Translation Ground/Supply-Sensing Applications
______________Ordering Information
PART MAX965ESA MAX965EUA MAX966ESA MAX966EUA MAX967ESA MAX967EUA TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 8 SO 8 MAX 8 SO 8 MAX 8 SO 8 MAX
_____________________Selector Guide
COMPARATORS PER PACKAGE PROGRAMMABLE HYSTERESIS
Ordering Information continued on last page. Pin Configurations appear at end of data sheet.
PART
INTERNAL REFERENCE
__________Typical Operating Circuit
VIN VCC 7 3 IN+ VCC OUT 4 IN5 HYST 8 VOUT RPULL-UP
MAX965 MAX966 MAX967 MAX968 MAX969 MAX970
Yes No Yes Yes Yes No
1 2 2 2 4 4
Yes No Yes Yes Yes No
6 REF 1.235V 1
MAX965
GND
Rail-to-Rail is a registered trademark of Nippon Motorola Ltd.
________________________________________________________________ Maxim Integrated Products
1
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Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators MAX965-MAX970
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 +70C)...............471mW 8-Pin MAX (derate 4.10mW/C above +70C) ..........330mW 14-Pin SO (derate 8.33mW/C above +70C).............667mW 16-Pin SO (derate 8.70mW/C above +70C).............696mW 16-Pin QSOP (derate 5.70mW/C above +70C)........457mW 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 = +1.6V to +5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 3V and TA = +25C.) PARAMETER POWER SUPPLIES All packages, TA = 0C to +85C Supply Voltage Range Comparator Minimum Operating Voltage MAX965 MAX966 Supply Current ICC MAX967/MAX968 MAX969 MAX970 Power-Up Time (VCC to output valid) COMPARATOR Power-Supply Rejection Ratio Common-Mode Voltage Range PSRR VCMR 1.7V VCC 5.5V TA = +25C TA = -40C to +85C SO package Common-mode QSOP package range = -0.25V to 1.3V, 0C to +85C MAX VCC > 1.8V package -40C to +85C SO package Full commonmode range Input Hysteresis Input Bias Current Input Offset Current Input Capacitance 2 VHYST IB IOS CIN HYST = REF Common-mode range = -0.25V to (VCC - 0.25V) Full common-mode range, TA = +25C QSOP package MAX package 0C to +85C -40C to +85C 1 0.001 0.001 0.2 7.0 5 50 -0.25 -0.25 0.1 1.0 VCC VCC - 0.25 3.0 4.0 4.0 6.0 7.0 10.0 10.0 15.0 mV nA pA pF mV mV/V V V VCC stepped 0V to 5V VCC SO/QSOP packages, TA = -40C to +85C MAX package, TA = -40C to +85C 1.6 1.7 1.8 1.0 7.0 6.0 10 14 11 20 12 10 16 22 18 s A 5.5 5.5 5.5 V V SYMBOL CONDITIONS MIN TYP MAX UNITS
Input Offset Voltage
VOS
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Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +1.6V to +5.5V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = 3V and TA = +25C.) PARAMETER Common-Mode Rejection Ratio HYST Input Voltage Range HYST Input Leakage Hysteresis Gain Input Voltage Noise OUT Output Voltage Low Propagation Delay REFERENCE SO package QSOP package MAX package, TA = 0C to +85C MAX package, TA = -40C to +85C HYST = REF f = 100Hz to 100kHz, CREF = 0.1F 1.125 1.205 1.205 1.185 15 200 1.235 1.235 1.235 1.235 50 400 10 1.255 1.265 1.265 1.285 en VOL tPDf = 100Hz to 100kHz, CREF = 1000pF IOUT = 100A, 1.6V < VCC < 2.7V IOUT = 500A, 2.7V < VCC < 5.5V RPULL-UP = 1M, CLOAD = 15pF, high to low 10mV overdrive 50mV overdrive 20 10 IHYST 1.0 10 0.2 0.4 SYMBOL CMRR VREF 0.05 CONDITIONS MIN TYP 1.5 MAX 4.0 VREF 5 UNITS mV/V V nA V/V VRMS V s
MAX965-MAX970
Reference Voltage
VREF
V V A nA VRMS
Source Current Sink Current Output Voltage Noise
IREF+ IREF-
__________________________________________Typical Operating Characteristics
(VCC = +3.0V, RPULL-UP = 100k, VCM = 0V, TA = +25C, unless otherwise noted.)
MAX965 SUPPLY CURRENT vs. TEMPERATURE
MAX965-TOC1b
MAX966 SUPPLY CURRENT vs. TEMPERATURE
MAX965-TOC2b
MAX967/MAX968 SUPPLY CURRENT vs. TEMPERATURE
14 13 SUPPLY CURRENT (A) 12 11 10 9 8 7 6 5 100 -60 -40 -20 0 20 40 VCC = 2.0V VIN+ > VIN60 80 100 VCC = 3.0V VCC = 5.0V
MAX965-TOC3b
13 12 11 SUPPLY CURRENT (A) 10 9 8 7 6 5 4 3 -60 -40 -20 0 20 40 60 80 VCC = 2.0V VIN+ > VINVCC = 3.0V VCC = 5.0V
9.0 8.5 8.0 SUPPLY CURRENT (A) 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 VCC = 2.0V VIN+ > VIN-60 -40 -20 0 20 40 60 80 VCC = 3.0V VCC = 5.0V
15
100
TEMPERATURE (C)
TEMPERATURE (C)
TEMPERATURE (C)
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Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators MAX965-MAX970
_____________________________Typical Operating Characteristics (continued)
(VCC = +3.0V, RPULL-UP = 100k, VCM = 0V, TA = +25C, unless otherwise noted.)
MAX969 SUPPLY CURRENT vs. TEMPERATURE
MAX965-TOC4b
MAX970 SUPPLY CURRENT vs. TEMPERATURE
MAX965-TOC5b
SUPPLY CURRENT PER COMPARATOR vs. SUPPLY VOLTAGE (EXCLUDES REFERENCE CURRENT)
SUPPLY CURRENT PER COMPARATOR (A)
MAX965-TOC6b
20 18 SUPPLY CURRENT (A) 16 VCC = 5.0V 14 12 10 VCC = 2.0V 8 -60 -40 -20 0 20 40 60 80 VIN+ > VINVCC = 3.0V
16 15 14 SUPPLY CURRENT (A) 13 12 11 10 9 8 7 VCC = 2.0V VIN+ > VIN-60 -40 -20 0 20 40 60 80 VCC = 5.0V
3.5 3.0 2.5 2.0 1.5 1.0 0.5 VIN+ > VIN0 0 1 2 3 4 5
VCC = 3.0V
100
100
6
TEMPERATURE (C)
TEMPERATURE (C)
SUPPLY VOLTAGE (V)
MAX965 SUPPLY CURRENT vs. SUPPLY VOLTAGE (INCLUDES REFERENCE CURRENT)
MAX965/70-TOC7a
COMPARATOR OUTPUT SHORT-CIRCUIT SINK CURRENT vs. TEMPERATURE
OUTPUT SHORT-CIRCUIT SINK CURRENT (mA)
MAX965/70 -TOC8a
COMPARATOR OUTPUT LOW VOLTAGE vs. SINK CURRENT
4.5 OUTPUT LOW VOLTAGE (V) 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 VCC = 2V VCC = 3V VCC = 5V VIN+ = < VINMAX965/70-09a
14 12 SUPPLY CURRENT (A) 10 8 6 4 2 VIN+ > VIN0 0 1 2 3 4 5
14 12 VCC = 5V 10 8 6 4 2 0 VCC = 2V VCC = 3V VIN+ < VIN-
5.0
0 -60 -40 -20 0 20 40 60 80 100 0 2 4 6 8 10 12 TEMPERATURE (C) SINK CURRENT (mA)
6
SUPPLY VOLTAGE (V)
PROPAGATION DELAY (tPD-) vs. TEMPERATURE
MAX965-TOC10a
PROPAGATION DELAY (tPD-) vs. CAPACITIVE LOAD
VOD = 50mV 60 50
MAX4108/9-11a
PROPAGATION DELAY (tPD-) vs. INPUT OVERDRIVE
MAX965-TOC12a
14 13 12 11 DELAY (s) VCC = 5.0V VCC = 3.0V VCC = 2.0V
70
30 25 20
DELAY (s)
40 30 20 10
VCC = 2.0V VCC = 3.0V
9 8 7 6 5 4 -60
DELAY (s)
10
15 VCC = 2.0V 10 5 VCC = 5.0V VCC = 3.0V
VOD = 50mV 0 -40 -20 0 20 40 60 80 100 0.001 0.01
VCC = 5.0V 0.1
0 0 20 40 60 80 100 120 140 160 INPUT OVERDRIVE (mV)
TEMPERATURE (C)
CAPACITIVE LOAD (F)
4
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Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators MAX965-MAX970
_____________________________Typical Operating Characteristics (continued)
(VCC = +3.0V, RPULL-UP = 100k, VCM = 0V, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT PER COMPARATOR vs. OUTPUT TRANSITION FREQUENCY
MAX965/70 TOC13A
INPUT OFFSET VOLTAGE vs. TEMPERATURE
MAX965/70-TOC14a
INPUT BIAS CURRENT vs. TEMPERATURE
3.5 INPUT BIAS CURRENT (pA) 3.0 2.5 2.0 1.5 1.0 0.5 0 VCC = 3.0V VCC = 5.0V
MAX965/70-TOC15a
4.0 SUPPLY CURRENT PER COMPARATOR (A) 3.8 3.6 3.4 3.2 3.0 2.8 2.6 2.4 2.2 2.0 0.01 0.1 1 10 VCC = 1.6V VCC = 5.5V
200 190 INPUT OFFSET VOLTAGE (V) 180 170 160 150 140 130 120 110 100
4.0
100
-60
-40
-20
0
20
40
60
80
100
-40
-20
0
20
40
60
80
100
OUTPUT TRANSITION FREQUENCY (kHz)
TEMPERATURE (C)
TEMPERATURE (C)
PROGRAMMED HYSTERESIS vs. COMMON-MODE VOLTAGE
MAX965/70 TOC16
REFERENCE VOLTAGE vs. TEMPERATURE
MAX965/70 TOC6a
REFERENCE VOLTAGE vs. SUPPLY VOLTAGE
1.237 REFERENCE VOLTAGE (V) 1.235 1.233 1.231 1.229 1.227 1.225 1.223
MAX965/70-TOC13
40 PROGRAMMED HYSTERESIS (mV) 35 30 25 20 15 10 5 0 0 VCC = 5.0V VHYST = 22mV (PROGRAMMED)
1.2345 VCC = 5V
1.239
REFERENCE VOLTAGE (V)
1.2340
1.2335
1.2330 VCC = 2V VCC = 3V 1.2320 -60 -40 -20 0 20 40 60 80 100
1.2325
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 COMMON-MODE VOLTAGE (V)
1.0
1.8
2.6
3.4 VCC (V)
4.2
5.0
5.8
TEMPERATURE (C)
REFERENCE VOLTAGE vs. SOURCE CURRENT
MAX965/70-TOC18a
PROPAGATION DELAY (tPD+)
MAX965/70-TOC15
1.4 1.3 REFERENCE VOLTAGE (V) 1.2 1.1 1.0 0.9 0.8 0.7 0.6 0 100 200 300 400 500 600
PROPAGATION DELAY (tPD-)
MAX965/70-TOC16b
VCC = 3V IN+ 50mV/div IN+ 50mV/div
VCC = 3V
OUT 2V/div
OUT 2V/div
700
2s/div
2s/div
SOURCE CURRENT (A)
_______________________________________________________________________________________
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Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators MAX965-MAX970
_____________________________Typical Operating Characteristics (continued)
(VCC = +3.0V, RPULL-UP = 100k, VCM = 0V, TA = +25C, unless otherwise noted.)
POWER-UP/DOWN RESPONSE
MAX965/70-TOC17
10kHz RESPONSE
MAX965/70-TOC18
VCC 2V/div
IN+ 50mV/div
OUT 2V/div
OUT 1V/div
5s/div
20s/div
_____________________________________________________________Pin Descriptions
MAX965-MAX968
PIN NAME MAX965 -- 1 2 3 -- 4 -- -- -- 5 6 7 8 -- 6 MAX966 1 2 -- -- 3 -- 4 5 6 -- -- 7 -- 8 MAX967 1 2 -- -- 3 -- -- -- 4 5 6 7 -- 8 MAX968 1 2 -- -- 3 -- -- 4 -- 5 6 7 -- 8 OUTA GND N.C. IN+ INA+ ININAINBINB+ HYST REF VCC OUT OUTB Comparator A Open-Drain Output Ground No Connection. Not internally connected. Comparator Noninverting Input Comparator A Noninverting Input Comparator Inverting Input Comparator A Inverting Input Comparator B Inverting Input Comparator B Noninverting Input Hysteresis Input. Connect HYST to REF if not used. Input voltage range is from VREF to (VREF - 50mV). Internal Reference Output. Typically 1.235V with respect to GND. Positive Supply Voltage, +1.6V to +5.5V Comparator Open-Drain Output Comparator B Open-Drain Output FUNCTION
_______________________________________________________________________________________
Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators MAX965-MAX970
________________________________________________Pin Descriptions (continued)
MAX969/MAX970
PIN MAX970 MAX969 SO 1 2 3 4 5 6 7 -- 8 9 10 11 12 13 14 15 16 1 2 3 4 5 6 7 -- -- -- 8 9 10 11 12 13 14 QSOP 1 2 3 4 5 6 7 8, 9 -- -- 10 11 12 13 14 15 16 OUTB OUTA VCC INAINA+ INBINB+ N.C. REF HYST INCINC+ INDIND+ GND OUTD OUTC Comparator B Open-Drain Output Comparator A Open-Drain Output Positive Supply Voltage, +1.6V to +5.5V Comparator A Inverting Input Comparator A Noninverting Input Comparator B Inverting Input Comparator B Noninverting Input No Connection. Not internally connected. Internal Reference Output. Typically 1.235V with respect to GND. Hysteresis Input. Connect to REF if not used. Input voltage range is from (VREF - 50mV) to VREF. Comparator C Inverting Input Comparator C Noninverting Input Comparator D Inverting Input Comparator D Noninverting Input Ground Comparator D Open-Drain Output Comparator C Open-Drain Output NAME FUNCTION
_______________Detailed Description
The MAX965-MAX970 single/dual/quad, micropower, ultra-low-voltage comparators feature Rail-to-Rail(R) 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 5A 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
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Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators MAX965-MAX970
________________________________________________________Functional Diagrams
VCC IN+ OUT INHYST OUTA
VCC OUTB
MAX966
REF + 1.235V REF
MAX965
INA+ INA-
INB+ INBGND
GND
INA+
VCC OUTA
INA+
VCC OUTA
REF HYST REF 1.235V INB+ GND OUTB
REF HYST REF 1.235V OUTB INB-
MAX967
GND
MAX968
OUTB OUTA
VCC
OUTC OUTD
OUTB OUTA
VCC
OUTC OUTD
INAINA+
IND+ IND-
INAINA+
IND+ IND-
INBINB+ REF 1.235V + REF GND HYST
INC+ INC-
INBINB+
INC+ INC-
MAX969
MAX970
GND
8
_______________________________________________________________________________________
Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
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.
Noise Considerations
The comparator has an effective wideband peak-topeak noise of around 10V. The voltage reference has peak-to-peak noise approaching 1.0mV with a 0.1F 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.
MAX965-MAX970
__________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.
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 50A. To reduce reference noise or to provide noise immunity, bypass REF with a capacitor (0.1nF to 0.1F).
VCC VCC 1.6V
IN+
1.0V VREF V+ t 100k
THRESHOLDS
R1 V+
47k
INVREF - VHYST
HYSTERESIS VHB BAND
VCC R2 150k REF OUT GND
MAX965
VTRIP = 1.22 R1 + 1 R2 V R1 = TRIP - 1 x R2 1.22
OUT
Figure 1. Operation below 1.6V
Figure 2. Threshold Hysteresis Band 9
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Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators MAX965-MAX970
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. 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 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 (12A typical), and is significantly larger than the HYST leakage current (5nA typical). IREF values between 0.1A and 4A are good choices. If 2.4M is chosen for R2 (IREF = 0.5A), the equation for R1 and VHB can be approximated as: R1(k) = 2 x VHB (mV) In the MAX967/MAX968/MAX969, the HYST pin programs the same hysteresis for all comparators in the package.
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 2.4M and 7.6m. For R3, choose the 2.2M standard value. 2) Choose the hysteresis band required (VHB). For this example, choose 50mV.
+1.6V TO +5.5V IREF REF R1
R3
VCC
VCC
R1
HYST R2 GND
MAX965 MAX967 MAX968 MAX969
VIN VCC R2 GND OUT
R4
VREF
MAX966 MAX970
Figure 3. Programming the HYST Pin 10
Figure 4. External Hysteresis
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Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators
3) Calculate R1: R1 = (R3 + R4) x (VHB / VCC). Putting in the values for this example, R1 = (2.2M + 10k) x (50mV / 5.0V) = 22.1k. 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: 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
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.
MAX965-MAX970
2-Cell to TTL Logic-Level Shifter
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.
R2 =
where V THR is the rising-voltage trip threshold. Choose a standard value of 15k. 6) Verify trip voltages and hysteresis as follows: VIN rising : 1 1 1 + VTHR = VREF x R1 x + R1 R2 R3 + R4 VIN falling : R1 x VCC VTHF = VTHR - R3 + R4 Hysteresis = VTHR - VTHF where VTHR is the rising-voltage trip point, and VTHF is the falling-voltage trip point.
VCC
R3 VCC 0.1F VCC HYST GND REF
VCC
RPULL-UP OUT
RD
MAX965
Figure 5. IR Receiver
2 CELLS
0.1F
+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
Single/Dual/Quad, Micropower, Ultra-Low-Voltage, Rail-to-Rail I/O Comparators MAX965-MAX970
__________________________________________________________Pin Configurations
TOP VIEW
GND 1 8 7 OUT VCC REF HYST OUTA 1 8 7 OUTB VCC INB+ INBOUTA 1 8 7 OUTB VCC REF HYST
N.C. 2 IN+ 3 IN- 4
GND 2 INA+ 3 INA- 4
GND 2 INA+ 3 INB+ 4 (INB-)
MAX965
6 5
MAX966
6 5
MAX967 MAX968
6 5
SO/MAX
SO/MAX
SO/MAX
OUTB 1 OUTA 2 VCC 3 INA- 4 INA+ 5 INB- 6 INB+ 7 REF 8
16 OUTC 15 OUTD 14 GND
OUTB 1 OUTA 2 VCC 3 INA- 4 INA+ 5 INB- 6 INB+ 7
14 OUTC 13 OUTD 12 GND
OUTB 1 OUTA 2 VCC 3 INA- 4 INA+ 5 INB- 6 INB+ 7 N.C. 8
16 OUTC 15 OUTD 14 GND
MAX969
13 IND+ 12 IND11 INC+ 10 INC9 HYST
MAX970
11 IND+ 10 IND9 8 INC+ INC-
MAX970
13 IND+ 12 IND11 INC+ 10 INC9 N.C.
SO
SO/QSOP
( ) ARE FOR MAX968 ONLY.
QSOP
_Ordering Information (continued)
PART MAX968ESA MAX968EUA MAX969ESE MAX969EEE MAX970ESD MAX970EEE TEMP. RANGE -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C -40C to +85C PIN-PACKAGE 8 SO 8 MAX 16 Narrow SO 16 QSOP 14 SO 16 QSOP
___________________Chip Information
TRANSISTOR COUNTS: MAX965 = 216 MAX966 = 190 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 (c) 1997 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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