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19-0450; Rev 3; 2/03
Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators
General Description
The MAX971-MAX974 and MAX981-MAX984 single/ dual/quad low-voltage comparators feature the lowest power consumption available. These micropower devices draw less than 4A supply current over temperature (MAX971/MAX972/MAX981/MAX982), and include an internal 1.182V 1% (MAX971/MAX973/ MAX974) or 2% (MAX981-MAX984) voltage reference and programmable hysteresis. Ideal for 3V or 5V single-supply applications, these devices operate from a single 2.5V to 11V supply (or 1.25V to 5.5V dual supplies), and each comparator's input voltage ranges from the negative supply rail to within 1.3V of the positive supply. The single MAX971/MAX981 and the dual MAX973/ MAX982/MAX983 provide a unique, simple method for adding hysteresis without feedback or complicated equations, simply by using the HYST pin plus two resistors. The MAX971-MAX974 and MAX981-MAX984's opendrain outputs permit wire-ORed configurations. Thanks to an 11V output range and separate GND pin for the output transistor (MAX971/MAX974, MAX981/MAX984), these devices are ideal for level translators and bipolar to singleended converters. For similar devices with complementary output stages, see the MAX921-MAX924 (1% reference) and the MAX931-MAX934 (2% reference).
COMPARATORS PER PACKAGE INTERNAL HYSTERESIS INTERNAL PRECISION REFERENCE
Features
o Available in Ultra-Small Packages: UCSPTM (MAX972) MAX (MAX9_1/MAX9_2/MAX9_3) o Ultra-Low Quiescent Current (4A, max) Over Extended Temp Range (MAX971/MAX981) o Power Supplies: Single 2.5V to 11V Dual 1.25V to 5.5V o Input Voltage Range Includes Negative Supply o Internal Bandgap Reference 1.182V 1% (MAX97_) 1.182V 2% (MAX98_) o 12s Propagation Delay (10mV Overdrive) o Output Has Separate GND Pin (MAX9_1/MAX9_4)
MAX971-MAX974/MAX981-MAX984
Applications
Battery-Powered Systems Threshold Detectors Window Comparators Level Translators Oscillator Circuits
Ordering Information
PART MAX971CPA MAX971CSA MAX971CUA TEMP RANGE 0C to +70C 0C to +70C 0C to +70C PIN-PACKAGE 8 Plastic Dip 8 SO 8 MAX
PACKAGE
Ordering Information continued at end of data sheet.
PART
Typical Operating Circuit
VIN 7 V+ 3 IN+ OUT 8 4 IN-
MAX971 MAX972 MAX973 MAX974 MAX981 MAX982 MAX983 MAX984
1% None 1% 1% 2% 2% 2% 2%
1 2 2 4 1 2 2 4
Yes No Yes No Yes Yes Yes No
8-Pin DIP/SO/MAX 8-Pin UCSP/ DIP/SO/MAX 8-Pin DIP/SO/MAX 16-Pin DIP/SO 8-Pin DIP/SO/MAX 8-Pin DIP/SO/MAX 8-Pin DIP/SO/MAX 16-Pin DIP/SO
5 HYST
6 REF V2
MAX971 MAX981
GND 1
THRESHOLD DETECTOR UCSP is a trademark of Maxim Integrated Products, Inc.
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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.
Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators MAX971-MAX974/MAX981-MAX984
ABSOLUTE MAXIMUM RATINGS
V+ to V-, V+ to GND, GND to V-................................-0.3V, +12V Inputs Current: IN_+, IN_-, HYST..............................................20mA Voltage: IN_+, IN_-, HYST ...............(V+ + 0.3V) to (V- - 0.3V) Outputs Current: REF...................................................................20mA OUT_ ................................................................50mA Voltage: REF ....................................(V+ + 0.3V) to (V- - 0.3V) OUT_ (MAX9_1/9_4)..................12V to (GND - 0.3V) (MAX9_2/9_3).......................12V to (V- - 0.3V) OUT_ Short-Circuit Duration ..................................Continuous Continuous Power Dissipation (TA = +70C) 8-Bump UCSP (derate 4.7mW/C above +70C) ........379mW 8-Pin Plastic DIP (derate 9.09mW/C above +70C) ...727mW 8-Pin SO (derate 5.88mW/C above +70C)................471mW 8-Pin MAX (derate 4.1mW/C above +70C) .............330mW 16-Pin Plastic DIP (derate 10.53mW/C above +70C)..842mW 16-Pin SO (derate 8.70mW/C above +70C) ................696mW Operating Temperature Ranges MAX97_C_ _/MAX98_C_ _ ..................................0C to +70C MAX97_E_ _/MAX98_E_ _ ...............................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10s) .................................+300C Bump Temperature (soldering) Reflow ..........................................................................+235C
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--5V OPERATION
(V+ = 5V, V- = GND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER POWER REQUIREMENTS Supply Voltage Range Output Voltage Range MAX9_1, HYST = REF IN+ = IN- + 100mV MAX972 MAX982/ MAX9_3, HYST = REF MAX9_4 COMPARATOR Input Offset Voltage Input Leakage Current (IN-, IN+) Input Leakage Current (HYST) Input Common-Mode Voltage Range Common-Mode Rejection Ratio Power-Supply Rejection Ratio Voltage Noise Hysteresis Input Voltage Range Response Time (High-to-Low Transition) Response Time (Low-to-High Transition) (Note 3) V- to (V+ - 1.3V) V+ = 2.5V to 11V 100Hz to 100kHz MAX9_1/MAX982/MAX9_3 TA = +25C, 100pF load, 1M pullup to V+ Overdrive = 10mV Overdrive = 100mV REF - 0.05 12 4 300 VCM = 2.5V IN+ = IN- = 2.5V MAX9_1/MAX982/MAX9_3 V0.1 0.1 20 REF C/E temp ranges 0.01 0.02 V+ - 1.3 1.0 1.0 10 5 mV nA nA V mV/V mV/V VRMS V s s TA = +25C C/E temp ranges TA = +25C C/E temp ranges TA = +25C C/E temp ranges TA = +25C C/E temp ranges 5.5 3.1 2.5 (Note 2) 2.5 0 2.5 11 11 3.2 4 3.2 4 4.5 6 6.5 8.5 A V V CONDITIONS MIN TYP MAX UNITS
Supply Current
TA = +25C, 100pF load, 1M pullup to V+
2
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Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators
ELECTRICAL CHARACTERISTICS--5V OPERATION (continued)
(V+ = 5V, V- = GND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
MAX971-MAX974/MAX981-MAX984
PARAMETER Output Low Voltage Output Leakage Current
CONDITIONS MAX9_2/MAX9_3, IOUT = 1.8mA MAX9_1/MAX9_4, IOUT = 1.8mA VOUT = 11V MAX971/MAX973/ MAX974 C temp range E temp range C temp range E temp range 1% 2% 2% 3%
MIN
TYP
MAX V- + 0.4 GND + 0.4 100
UNITS V nA
REFERENCE (MAX9_1/MAX982/MAX9_3/MAX9_4 ONLY) 1.170 1.158 1.158 1.147 15 6 8 4 100 15 25 1.182 1.182 1.194 1.206 1.206 1.217 A A VRMS V
Reference Voltage MAX981-MAX984 Source Current Sink Current Voltage Noise TA = +25C C/E temp ranges TA = +25C C/E temp ranges 100Hz to 100kHz
ELECTRICAL CHARACTERISTICS--3V OPERATION
(V+ = 3V, V- = GND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER POWER REQUIREMENTS MAX9_1 MAX972 MAX982/ MAX9_3 MAX9_4 COMPARATOR Input Offset Voltage Input Leakage Current (IN-, IN+) Input Leakage Current (HYST) Input Common-Mode Voltage Range Common-Mode Rejection Ratio Power-Supply Rejection Ratio Voltage Noise Hysteresis Input Voltage Range VCM = 1.5V IN+ = IN- = 1.5V MAX9_1/MAX982/MAX9_3 VV- to (V+ - 1.3V) V+ = 2.5V to 11V 100Hz to 100kHz MAX9_1/MAX982/MAX9_3 REF - 0.05 0.2 0.1 20 REF C/E temp ranges 0.01 0.02 V+ - 1.3 1 1 10 5 mV nA nA V mV/V mV/V VRMS V TA = +25C C/E temp ranges TA = +25C C/E temp ranges TA = +25C C/E temp ranges TA = +25C C/E temp ranges 5.2 3.4 2.4 2.4 3.0 3.8 3.0 3.8 4.3 5.8 6.2 8.0 A CONDITIONS MIN TYP MAX UNITS
Supply Current
HYST = REF, IN+ = (IN- + 100mV)
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Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators MAX971-MAX974/MAX981-MAX984
ELECTRICAL CHARACTERISTICS--3V OPERATION (continued)
(V+ = 3V, V- = GND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) (Note 1)
PARAMETER Response Time (High-to-Low Transition) Response Time (Low-to-High Transition) (Note 3) Output Low Voltage Output Leakage Current REFERENCE MAX971/MAX973/ MAX974 Reference Voltage MAX981-MAX984 Source Current Sink Current Voltage Noise TA = +25C C/E temp ranges TA = +25C C/E temp ranges 100Hz to 100kHz C temp range E temp range C temp range E temp range 1% 2% 2% 3% 1.170 1.158 1.158 1.147 15 6 8 4 100 15 25 1.182 1.182 1.194 1.206 1.206 1.217 A A VRMS V CONDITIONS TA = +25C, 100pF load, 1M pullup to V+ Overdrive = 10mV Overdrive = 100mV MIN TYP 12 4 300 V- + 0.4 GND + 0.4 100 MAX UNITS s s V nA
TA = +25C, 100pF load, 1M pullup to V+ MAX9_2/MAX9_3, IOUT = 0.8mA MAX9_1/MAX9_4, IOUT = 0.8mA VOUT = 11V
Note 1: The MAX972EBL is 100% tested at TA = +25C. Temperature limits are guaranteed by design. Note 2: MAX974/MAX984 comparators work below 2.5V; see Low-Voltage Operation section for more details. Note 3: Low-to-high response time is the result of the 1M pullup and the 100pF capacitive load, based on three time constants. A faster response time is achieved with a smaller RC.
4
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Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators
__________________________________________Typical Operating Characteristics
(V+ = 5V, V- = GND = 0V, TA = +25C, unless otherwise noted.)
OUTPUT VOLTAGE LOW vs. LOAD CURRENT
MAX971-4/981-4-TOC1
MAX971-MAX974/MAX981-MAX984
REFERENCE OUTPUT VOLTAGE vs. OUTPUT LOAD CURRENT
MAX971-4/981-4 TOC2
MAX971/MAX973/MAX974 REFERENCE VOLTAGE vs. TEMPERATURE
1.21 REFERENCE VOLTAGE (V) 1.20 1.19 1.18 1.17 1.16 1.15 1.14 EXTENDED TEMP RANGE COMMERCIAL TEMP RANGE
MAX971-4/981-4 TOC3
2.5
V+ = 5V
1.190 REFERENCE OUTPUT VOLTAGE (V) SINK 1.185 1.180 SOURCE 1.175 1.170 1.165 1.160 1.155 V+ = 5V OR V+ = 3V 0 5 10 15 20 25
1.22
2.0 V+ = 3V VOL (V) 1.5
1.0
0.5
0 0 4 8 12 16 20 LOAD CURRENT (mA)
30
-60 -40 -20 0
20 40 60 80 100 120 140
OUTPUT LOAD CURRENT (A)
TEMPERATURE (C)
MAX9_1 SUPPLY CURRENT vs. TEMPERATURE
MAX971-4/981-4 TOC4
MAX972 SUPPLY CURRENT vs. TEMPERATURE
MAX971-4/981-4 TOC5
MAX982/MAX9_3 SUPPLY CURRENT vs. TEMPERATURE
MAX971-4/981-4 TOC6
4.5 IN+ = IN- + 100mV SUPPLY CURRENT (A) 4.0 V+ = 5V, V- = - 5V
4.5 IN+ = (IN- + 100mV) 4.0 SUPPLY CURRENT (A) 3.5 V+ = 10V, V- = 0V 3.0 2.5 V+ = 5V, V- = 0V 2.0 V+ = 3V, V- = 0V 1.5
5.0 4.5 SUPPLY CURRENT (A) 4.0 V+ = 5V, V- = 0V 3.5 3.0 2.5 V+ = 3V, V- = 0V 2.0
3.5
3.0 V+ = 3V, V- = 0V 2.5 V+ = 5V, V- = 0V 2.0 -60 -20 20 60 100 140 TEMPERATURE (C)
-60
-20
20
60
100
140
-60
-20
20
60
100
140
TEMPERATURE (C)
TEMPERATURE (C)
MAX9_4 SUPPLY CURRENT vs. TEMPERATURE
MAX971-4/981-4 TOC7
MAX9_4 SUPPLY CURRENT vs. LOW SUPPLY VOLTAGES
MAX971-4/981-4 TOC8
MAX9_1/MAX982/MAX9_3 HYSTERESIS CONTROL
60 40 IN+ - IN- (V) 20 0 -20 -40 OUTPUT LOW -60 -80 NO CHANGE
MAX971-4/981-4 TOC9
10 IN+ = (IN- + 100mV) 9 SUPPLY CURRENT (A) 8 7 6 5 4 3 -60 -20 20 60 100 V+ = 5V, V- = 0V V+ = 3V, V- = 0V V+ = 5V, V- = -5V
10
80 OUTPUT HIGH
SUPPLY CURRENT (A)
1
0.1
140
0.01 1.0 1.5 2.0 2.5 SINGLE-SUPPLY VOLTAGE (V)
0
10
20
30
40
50
TEMPERATURE (C)
VREF - VHYST (mV)
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5
Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators
Typical Operating Characteristics (continued)
(V+ = 5V, V- = GND = 0V, TA = +25C, unless otherwise noted.)
MAX9_1/MAX972/MAX9_4 TRANSFER FUNCTION
MAX971-4/981-4 TOC10
RESPONSE TIME vs. LOAD CAPACITANCE
MAX971-4/981-4 TOC11
RESPONSE TIME FOR VARIOUS INPUT OVERDRIVES (VOHL)
5 VOUT (V) 4 3 2 1 0 VIN (mV) 100 0 50mV 100mV 20mV 10mV
MAX971-4/981-4 TOC12
5.0 4.5 4.0 OUTPUT VOLTAGE (V) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 -0.3
10k
+5V
100k
18 V- = 0V 16 RESPONSE TIME (s) 14 12 10 8 6 4 2 VOHL
V0
10F
0.2 0.1 -0.2 -0.1 0 IN+ INPUT VOLTAGE (mV)
0.3
0
20
40
60
80
100
-2
2
6
10
14
18
LOAD CAPACITANCE (nF)
RESPONSE TIME (s)
RESPONSE TIME AT LOW SUPPLY VOLTAGES (VOHL)
MAX971-4/981-4 TOC13
MAX9_4 SINK CURRENT AT LOW SUPPLY VOLTAGES
MAX971-4/981-4 TOC14
SHORT-CIRCUIT SINK CURRENT vs. SUPPLY VOLTAGE
OUT CONNECTED TO V+ GND CONNECTED TO V20 SINK CURRENT (mA)
MAX971-4/981-4 TOC15
1000 RPULLUP = 10k
100
25
RESPONSE TIME (s)
100
CURRENT (mA)
10
15
10 -100mV
-20mV
1
10
5 SINK CURRENT AT VOUT = 0.4V 0.1
1 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 SINGLE-SUPPLY VOLTAGE (V)
1.0
1.5
2.0
2.5
0 0 5 TOTAL SUPPLY VOLTAGE (V) 10
SINGLE-SUPPLY VOLTAGE (V)
6
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Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators
Pin Description
PIN MAX971/ MAX981 DIP/SO/ MAX 1 2 3 4 5 6 7 8 -- -- -- -- -- -- MAX972 DIP/SO/ MAX -- 2 -- -- -- -- 7 -- 1 3 4 5 6 8 MAX982 DIP/SO/ MAX -- 2 -- -- 5 6 7 -- 1 3 -- -- 4 8 MAX973/ MAX983 DIP/SO/ MAX -- 2 -- -- 5 6 7 -- 1 3 -- 4 -- 8 GND VIN+ INHYST REF V+ OUT OUTA INA+ INAINBINB+ OUTB Ground. Connect to V- for single-supply operation. Negative Supply. Connect to GND for single-supply operation (MAX9_1). Noninverting Comparator Input Inverting Comparator Input Hysteresis Input. Connect to REF if not used. Input voltage range is from VREF to (VREF - 50mV). Reference Output. 1.182V with respect to V-. Positive Supply Comparator Output. Sinks current to GND. Comparator A Open-Drain Output. Sinks current to V-. Noninverting Input of Comparator A Inverting Input of Comparator A Inverting Input of Comparator B Noninverting Input of Comparator B Comparator B Open-Drain Output. Sinks current to V-.
MAX971-MAX974/MAX981-MAX984
NAME
FUNCTION
UCSP -- C2 -- -- -- -- A2 -- A1 C1 B1 B3 C3 A3
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Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators MAX971-MAX974/MAX981-MAX984
Pin Description (continued)
PIN MAX974 MAX984 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 NAME FUNCTION
OUTB OUTA V+ INAINA+ INBINB+ REF VINCINC+ INDIND+ GND OUTD OUTC
Comparator B Open-Drain Output. Sinks current to GND. Comparator A Open-Drain Output. Sinks current to GND. Positive Supply Inverting Input of Comparator A Noninverting Input of Comparator A Inverting Input of Comparator B Noninverting Input of Comparator B Reference Output. 1.182V with respect to V-. Negative Supply. Connect to ground for single-supply operation. Inverting Input of Comparator C Noninverting Input of Comparator C Inverting Input of Comparator D Noninverting Input of Comparator D Ground. Connect to V- for single-supply operation. Comparator D Open-Drain Output. Sinks current to GND. Comparator C Open-Drain Output. Sinks current to GND.
8
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Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators
Detailed Description
The MAX971-MAX974/MAX981-MAX984 comprise various combinations of a micropower 1.182V reference and micropower comparators. The Typical Operating Circuit shows the MAX971/MAX981 configuration, and Figures 1a-1d show the MAX9_2-MAX9_4 configurations. Internal hysteresis in the MAX9_1, MAX982, and MAX9_3 provides the easiest method for implementing hysteresis. It also produces faster hysteresis action and consumes much less current than circuits using external positive feedback.
Power-Supply and Input Signal Ranges
This family of devices operates from a single 2.5V to 11V power supply. The MAX9_1 and MAX9_4 have a separate ground for the output driver, allowing operation with dual supplies ranging from 1.25V to 5.5V. Connect V- to GND when operating the MAX9_1 or MAX9_4 from a single supply. The maximum total supply voltage in this case is still 11V. For proper comparator operation, the input signal can range from the negative supply (V-) to within one volt of the positive supply (V+ - 1V). The guaranteed commonmode input voltage range extends from V- to (V+ 1.3V). The inputs can be taken above and below the supply rails by up to 300mV without damage.
MAX971-MAX974/MAX981-MAX984
1 (A1) OUTA 2 (C2) V3 (C1) INA+ 4 (B1) INA-
MAX972
OUTB 8 (A3) V+ 7 (A2) INB+ 6 (C3) INB- 5 (B3)
1 OUTA 2 V3 INA+ 4 INBV-
MAX9_3
OUTB 8 V+ 7 REF 6 HYST 5
( ) BUMPS FOR THE UCSP
Figure 1c. MAX973/MAX983 Functional Diagram (Window Comparator)
Figure 1a. MAX972 Functional Diagram
1 OUTB 2 OUTA 3 V+
MAX9_4
OUTC 16 OUTD 15 GND 14 IND+ 13 IND- 12
1 OUTA 2 V3 INA+ 4 INB+ V-
MAX982
4 INAOUTB 8 5 INA+ V+ 7 REF 6 6 INBHYST 5 7 INB+ 8 REF
INC+ 11 INC- 10 V- 9
Figure 1b. MAX982 Functional Diagram
Figure 1d. MAX974/MAX984 Functional Diagram 9
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Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators MAX971-MAX974/MAX981-MAX984
The negative supply does not affect the output sink current. The positive supply provides gate drive for the output N-channel MOSFET and heavily influences the output current capability, especially at low supply voltages (see Typical Operating Characteristics section). The MAX9_2 and MAX9_3 have no GND pin, and their outputs sink current to V-.
IN+
THRESHOLDS
INVREF - VHYST
HYSTERESIS VHB BAND
Voltage Reference
The internal bandgap voltage reference has an output of 1.182V above V-. Note that the REF voltage is referenced to V-, not to GND. Its accuracy is 1% (MAX971/MAX973/MAX974) or 2% (MAX981-MAX984) in the 0C to +70C range. The REF output is typically capable of sourcing 25A and sinking 15A. Do not bypass the REF output.
OUT
Noise Considerations
Figure 2. Threshold Hysteresis Band
Low-Voltage Operation: V+ = 1V (MAX9_4 Only)
The guaranteed minimum operating voltage is 2.5V (or 1.25V). As the total supply voltage falls below 2.5V, performance degrades and the supply current falls. The reference will not function below about 2.2V, although the comparators will continue to operate with a total supply voltage as low as 1V. While the MAX9_4 has comparators that may be used at supply voltages below 2V, the MAX9_1/MAX9_2/MAX9_3 may not be used with supply voltages below 2.5V. At low supply voltages, the comparators' output sink capability is reduced and the propagation delay increases (see Typical Operating Characteristics). The useful input voltage range extends from the negative supply to a little under 1V below the positive supply, which is slightly closer to the positive rail than when the device operates from higher supply voltages. Test your prototype over the full temperature and supply-voltage range if you anticipate operation below 2.5V.
Although the comparators have a very high gain, useful gain is limited by noise. This is shown in the Transfer Function graph (see Typical Operating Characteristics). As the input voltage approaches the comparator's offset, the output begins to bounce back and forth; this peaks when VIN = VOS. (The lowpass filter shown on the graph averages out the bouncing, making the transfer function easy to observe.) Consequently, the comparator has an effective wideband peak-to-peak noise of around 300V. The voltage reference has peak-to-peak noise approaching 1mV. Thus, when a comparator is used with the reference, the combined peak-to-peak noise is about 1mV. This, of course, is much higher than the RMS noise of the individual components. Take care in your layout to avoid capacitive coupling from any output to the reference pin. Crosstalk can significantly increase the actual noise of the reference.
Comparator Output
With 100mV of overdrive, propagation delay is typically 3s. The Typical Operating Characteristics show the propagation delay for various overdrive levels. The open-drain outputs are intended for wire-ORed and level-shifting applications. The maximum output voltage is 11V above V-, and may be applied even when no supply voltage is present (V+ = V-). The MAX9_1 and MAX9_4 outputs sink current to GND, making these devices ideal for bipolar to single-ended conversion and level-shifting applications.
R1
IREF
6 REF
2.5V TO 11V 7 V+
MAX9_1 MAX982 MAX9_3
5 HYST V2
R2
Figure 3. Programming the HYST Pin
10
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Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators
__________Applications Information
Hysteresis
Hysteresis increases the comparators' noise margin by increasing the upper threshold and decreasing the lower threshold (Figure 2). Hysteresis (MAX9_1/MAX982/MAX9_3) To add hysteresis to the MAX9_1, MAX982, or MAX9_3, connect resistor R1 between REF and HYST, and connect resistor R2 between HYST and V- (Figure 3). If no hysteresis is required, connect HYST to REF. When hysteresis is added, the upper threshold increases by the same amount that the lower threshold decreases. The hysteresis band (the difference between the upper and lower thresholds, VHB) is approximately equal to twice the voltage between REF and HYST. The HYST input can be adjusted to a maximum voltage of REF and to a minimum voltage of (REF - 50mV). The maximum difference between REF and HYST (50mV) will therefore produce a 100mV (max) hysteresis band. Use the following equations to determine R1 and R2: VHB R1 = 2 x IREF
VIN RH V+
MAX971-MAX974/MAX981-MAX984
RPULLUP V+ OUT
MAX9_4 VGND VREF
Figure 4. External Hysteresis
Board Layout and Bypassing
Power-supply bypass capacitors are not needed if the supply impedance is low, but 100nF bypass capacitors should be used when the supply impedance is high or when the supply leads are long. Minimize signal lead lengths to reduce stray capacitance between the input and output that might cause instability. Do not bypass the reference output.
(
)
VHB 1.182 - 2 R2 = IREF where I REF (the current sourced by the reference) should not exceed the REF source capability, and should be significantly larger than the HYST input current. IREF values between 0.1A and 4A are usually appropriate. If 2.4M is chosen for R2 (IREF = 0.5A), the equation for R1 and VHB can be approximated as: R1 (k) = VHB (mV) When hysteresis is obtained in this manner for the MAX982/MAX9_3, the same hysteresis applies to both comparators. Hysteresis (MAX972/MAX9_4) Hysteresis can be implemented with any comparator using positive feedback, as shown in Figure 4. This approach generally draws more current than circuits using the HYST pin on the MAX9_1/MAX982/MAX9_3, and the high feedback impedance slows hysteresis. In addition, because the output does not source current, any increase in the upper threshold is dependent on the load or pullup resistor on the output.
Window Detector
The MAX9_3 is ideal for making window detectors (undervoltage/overvoltage detectors). The schematic is shown in Figure 5, with component values selected for a 4.5V undervoltage threshold and a 5.5V overvoltage threshold. Choose different thresholds by changing the values of R1, R2, and R3. To prevent chatter at the output when the supply voltage is close to a threshold, hysteresis has been added using R4 and R5. Taken alone, OUTA would provide an active-low undervoltage indication, and OUTB would give an active-low overvoltage indication. Wired-ORing the two outputs provides an active-high, power-good signal. The design procedure is as follows: 1) Choose the required hysteresis level and calculate values for R4 and R5 according to the formulas in the Hysteresis (MAX9_1/MAX982/MAX9_3) section. In this example, 5mV of hysteresis has been added at the comparator input (VH = VHB/2). This means that the hysteresis apparent at V IN will be larger because of the input resistor divider.
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11
Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators MAX971-MAX974/MAX981-MAX984
2) Select R1. The leakage current into INB- is normally under 1nA, so the current through R1 should exceed 100nA for the thresholds to be accurate. R1 values up to about 10M can be used, but values in the 100k to 1M range are usually easier to deal with. In this example, choose R1 = 294k. 3) Calculate R2 + R3. The overvoltage threshold should be 5.5V when V IN is rising. The design equation is as follows:
VIN R3 1M
VOTH = 5.5V VUTH = 4.5V
5V 7 V+ OUTA 1
3 INA+
1M
VOTH R2 + R3 = R1 x - 1 VREF + VH 5.5 = 294k x - 1 (1.182 + 0.005) = 1.068M
4) Calculate R2. The undervoltage threshold should be 4.5V when VIN is falling. The design equation is as follows:
R2 = (R1 + R2 + R 3) x (VREF - VH ) - R1 VUTH (1.182 - 0.005) 4.5
5 HYST R2 62.2k R5 10k R4 2.4M 6 REF OUTB 8 4 INBR1 294k V2 POWER GOOD
MAX9_3
= (294k + 1.068M) x - 294k = 62.2k
Figure 5. Window Detector
Choose R2 = 61.9k (1% s tan dard value).
Battery Switchover Circuit
The switchover from line-powered DC to a backup battery is often accomplished with diodes. But this simple method is sometimes unacceptable, due to the voltage drop and associated power loss across the diode in series with the battery. Figure 6's circuit replaces the diode with a P-channel MOSFET controlled by one of the MAX9_3 comparator outputs. When the DC wall adapter drops below 4V (determined by R1 and R2), OUTA goes low, turning on Q1. Comparator B is used to measure the battery voltage, and gives a "low-battery" indication when the battery drops below 3.6V.
5) Calculate R3:
R3 = (R2 + R3 ) - R2 = 1.068M - 61.9 k = 1.006M
Choose R3 = 1M (1% standard value) 6) Verify the resistor values. The equations are as follows, evaluated for the above example: Overvoltage Threshold: (R1 + R2 + R3) VOTH = (VREF + VH ) x R1 = 5.474V Undervoltage Threshold : (R1 + R2 + R3) VUTH = (VREF - VH ) x (R1 + R2) = 4.484V where the hysteresis voltage VH = VREF x R5 . R4
Level-Shifter
Figure 7 shows a circuit to shift from bipolar 5V inputs to single-ended 5V outputs. The 10k resistors protect the comparator inputs, and do not materially affect the circuit's operation.
12
______________________________________________________________________________________
Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators MAX971-MAX974/MAX981-MAX984
5V
WALL ADAPTER 9V DC Q1 STEP-DOWN REGULATOR
3.3V
3 V+ 10k
3.3V LOGIC SUPPLY
VINA
5 INA+
MAX974 MAX984
OUTA 2
4
1M 7 V+
INA-
10k VINB 7 INB+ OUTB 1
BATTERY (4 CELLS) 953k 4 INB470k
MAX973 MAX983
OUTB 8
10k
6 INB10k VINC
11 INC+ OUTC 16 10 INC-
LOW BATT 1 OUTA R1 110k DC OK
10k
3 INA+ REF 6 R2 47k V2 20k HYST 5 2.4M
VIND
13 IND+ OUTD 15 12 INDREF GND 14 V9 -5V 8
N.C.
Figure 6. Battery Switchover Circuit
Figure 7. Level Shifter: 5V Input to Single-Ended 3.3V Output
UCSP Applications Information
For the latest application details on UCSP contruction, dimensions, tape carrier information, printed circuit board techniques, bump-pad layout and recommended reflow temperature profile as well as the latest information on reliability testing results, go to Maxim's web site at www.maxim-ic.com/ucsp to find the Application Note: UCSP-A Wafer-Level Chip-Scale Package.
______________________________________________________________________________________
13
Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators MAX971-MAX974/MAX981-MAX984
Pin Configurations
TOP VIEW
GND
1
8 7
OUT V+ REF HYST
OUTA
1
8 7
OUTB V+ INB+ INB-
OUTA
1
8 7
OUTB V+ REF HYST
V- 2 IN+ 3 IN- 4
V- 2 INA+ 3 INA- 4
V- 2 INA+ 3 INB+ 4
MAX971 MAX981
6 5
MAX972
6 5
MAX982
6 5
DIP/SO/MAX TOP VIEW (BUMPS ON BOTTOM)
1 A
OUTA
DIP/SO/MAX
DIP/SO/MAX
2
V+
3
OUTB
OUTA
1
8 7
OUTB V+ REF HYST
OUTB 1 OUTA 2 V+ 3 INA- 4 INA+ 5
16 OUTC 15 OUTD 14 GND
V- 2 B
INA-
MAX972
INB-
INA+ 3 INB- 4
MAX973 MAX983
6 5
MAX974 MAX984
13 IND+ 12 IND11 INC+ 10 INC9 V-
C
INA+
V-
INB+
DIP/SO/MAX
INB- 6 INB+ 7 REF 8
UCSP
DIP/Narrow SO
14
______________________________________________________________________________________
Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators
Ordering Information (continued)
PART MAX971EPA MAX971ESA MAX972CPA MAX972CSA MAX972CUA MAX972EBL-T* MAX972EPA MAX972ESA MAX973CPA MAX973CSA MAX973CUA MAX973EPA MAX973ESA MAX974CPE MAX974CSE MAX974EPE MAX974ESE MAX981CPA TEMP RANGE -40C to +85C -40C to +85C 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C -40C to +85C 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C PIN-PACKAGE 8 Plastic Dip 8 SO 8 Plastic Dip 8 SO 8 MAX 8 UCSP-8 8 Plastic Dip 8 SO 8 Plastic Dip 8 SO 8 MAX 8 Plastic Dip 8 SO 16 Plastic Dip 16 Narrow SO 16 Plastic Dip 16 Narrow SO 8 Plastic Dip PART MAX981CSA MAX981CUA MAX981EPA MAX981ESA MAX982CPA MAX982CSA MAX982CUA MAX982EPA MAX982ESA MAX983CPA MAX983CSA MAX983CUA MAX983EPA MAX983ESA MAX984CPE MAX984CSE MAX984EPE MAX984ESE TEMP RANGE 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C 0C to +70C -40C to +85C -40C to +85C 0C to +70C 0C to +70C -40C to +85C -40C to +85C PIN-PACKAGE 8 SO 8 MAX 8 Plastic Dip 8 SO 8 Plastic Dip 8 SO 8 MAX 8 Plastic Dip 8 SO 8 Plastic Dip 8 SO 8 MAX 8 Plastic Dip 8 SO 16 Plastic Dip 16 Narrow SO 16 Plastic Dip 16 Narrow SO
MAX971-MAX974/MAX981-MAX984
*UCSP top mark is "ABC."
___________________Chip Information
MAX971/MAX972/MAX973/MAX981/MAX982/MAX984 TRANSISTOR COUNT: 164 MAX974/MAX984 TRANSISTOR COUNT: 267
______________________________________________________________________________________
15
Ultra-Low-Power, Open-Drain, Single/Dual-Supply Comparators MAX971-MAX974/MAX981-MAX984
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.)
8LUMAXD.EPS
4X S
8
8
INCHES DIM A A1 A2 b MIN 0.002 0.030 MAX 0.043 0.006 0.037
MILLIMETERS MAX MIN 0.05 0.75 1.10 0.15 0.95
y 0.500.1
E
H
0.60.1
c D e E H L
1
1
0.60.1
S
D
BOTTOM VIEW
0.010 0.014 0.005 0.007 0.116 0.120 0.0256 BSC 0.116 0.120 0.188 0.198 0.016 0.026 6 0 0.0207 BSC
0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0 6 0.5250 BSC
TOP VIEW
A2
A1
A
c e b L
SIDE VIEW
FRONT VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, 8L uMAX/uSOP
APPROVAL DOCUMENT CONTROL NO. REV.
21-0036
1 1
J
INCHES DIM A A1 B C e E H L 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
MILLIMETERS 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 1.27
N
E
H
VARIATIONS:
1
INCHES
MILLIMETERS MIN 4.80 8.55 9.80 MAX 5.00 8.75 10.00 N MS012 8 AA 14 AB 16 AC
TOP VIEW
DIM D D D
MIN 0.189 0.337 0.386
MAX 0.197 0.344 0.394
D C
A e B A1
0-8 L
FRONT VIEW
SIDE VIEW
PROPRIETARY INFORMATION TITLE:
PACKAGE OUTLINE, .150" SOIC
APPROVAL DOCUMENT CONTROL NO. REV.
21-0041
B
1 1
16
______________________________________________________________________________________
SOICN .EPS
Ultra Low-Power, Open-Drain, Single/Dual-Supply Comparators
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.)
9LUCSP, 3x3.EPS
MAX971-MAX974/MAX981-MAX984
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 ____________________ 17 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
PDIPN.EPS

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