MAXIM MAX973CPA

19-0450; Rev 0; 11/95
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
PACKAGE
INTERNAL
HYSTERESIS
COMPARATORS
PER
PACKAGE
INTERNAL
PRECISION
REFERENCE
PART
____________________________Features
♦ µMAX Package—Smallest 8-Pin SO
(MAX9_1/MAX9_2/MAX9_3)
♦ Ultra-Low 4µA Max Quiescent Current
Over Extended Temp. Range (MAX971/MAX981)
♦ Power Supplies: Single +2.5V to +11V
Dual ±1.25V to ±5.5V
♦ Input Voltage Range Includes Negative Supply
♦ Internal 1.182V ±1% Bandgap Reference
♦ 12µs Propagation Delay (10mV Overdrive)
♦ Output Has Separate GND Pin (MAX9_1/MAX9_4)
________________________Applications
Battery-Powered Systems
Threshold Detectors
Window Comparators
Level Translators
Oscillator Circuits
______________Ordering Information
PART
TEMP. RANGE
MAX971CPA
0°C to +70°C
PIN-PACKAGE
8 Plastic DIP
MAX971CSA
0°C to +70°C
8 SO
MAX971CUA
MAX971C/D
0°C to +70°C
0°C to +70°C
8 µMAX
Dice*
Ordering Information continued at end of data sheet.
* Dice are tested at TA = +25°C, DC parameters only.
__________Typical Operating Circuit
MAX971
1%
1
Yes
8-Pin
DIP/SO/µMAX
MAX972
None
2
No
8-Pin
DIP/SO/µMAX
MAX973
1%
2
Yes
8-Pin
DIP/SO/µMAX
3 IN+
MAX974
1%
4
No
16-Pin DIP/SO
4 IN-
MAX981
2%
1
Yes
8-Pin
DIP/SO/µMAX
5 HYST
MAX982
2%
2
Yes
8-Pin
DIP/SO/µMAX
MAX983
2%
2
Yes
8-Pin
DIP/SO/µMAX
MAX984
2%
4
No
16-Pin DIP/SO
VIN
7
V+
OUT 8
MAX971
MAX981
6 REF
V2
GND
1
THRESHOLD DETECTOR
________________________________________________________________ Maxim Integrated Products
Call toll free 1-800-998-8800 for free samples or literature.
1
MAX971–MAX974/MAX981–MAX984
_______________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 4µA 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 and MAX981 and the dual MAX973
and 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).
MAX971–MAX974/MAX981–MAX984
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
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 = +70°C)
8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) ...727mW
8-Pin SO (derate 5.88mW/°C above +70°C)................471mW
8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW
8-Pin CERDIP (derate 8.00mW/°C above +70°C)........640mW
16-Pin Plastic DIP (derate 10.53mW/°C above +70°C)..842mW
16-Pin SO (derate 8.70mW/°C above +70°C) ................696mW
16-Pin CERDIP (derate 10.00mW/°C above +70°C) ......800mW
Operating Temperature Ranges
MAX97_C_ _/MAX98_C_ _ ..................................0°C to +70°C
MAX97_E_ _/MAX98_E_ _ ...............................-40°C to +85°C
MAX97_MJ_/MAX98_MJ_ .............................-55°C to +125°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: 5V OPERATION
(V+ = 5V, V- = GND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
2.5
11
V
0
11
V
POWER REQUIREMENTS
Supply Voltage Range
(Note 1)
Output Voltage Range
TA = +25°C
2.5
MAX9_1,
C/E temp. ranges
HYST = REF
M temp. range
4
5
TA = +25°C
MAX972
Supply Current
COMPARATOR
Input Offset Voltage
IN+ = IN- + 100mV
5
TA = +25°C
MAX982/
MAX9_3,
C/E temp. ranges
HYST = REF M temp. range
TA = +25°C
C/E temp. ranges
MAX9_4
M temp. range
3.1
4.5
5.5
6
7.5
6.5
8.5
11
±0.01
±10
±5
±40
VCM = 2.5V
C/E temp. ranges
M temp. range
Input Leakage Current (HYST)
Input Common-Mode Voltage Range
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
Voltage Noise
Hysteresis Input Voltage Range
MAX9_1/MAX982/MAX9_3
Response Time
(high-to-low transition)
TA = +25°C, 100pF load,
1MΩ pull-up to V+
Response Time
(low-to-high transition) (Note 2)
TA = +25°C, 100pF load, 1MΩ pull-up to V+
3.2
4
M temp. range
IN+ = IN- = 2.5V
2
2.5
C/E temp. ranges
Input Leakage Current (IN-, IN+)
3.2
±0.02
V-
V- to (V+ - 1.3V)
V+ = 2.5V to 11V
100Hz to 100kHz
MAX9_1/MAX982/MAX9_3
0.1
0.1
20
REF - 0.05
Overdrive = 10mV
Overdrive = 100mV
V+ - 1.3
1.0
1.0
REF
µA
mV
nA
nA
V
mV/V
mV/V
µVRMS
V
12
4
µs
300
µs
_______________________________________________________________________________________
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
MAX971–MAX974/MAX981–MAX984
ELECTRICAL CHARACTERISTICS: 5V OPERATION (continued)
(V+ = 5V, V- = GND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
Output Low Voltage
Output Leakage Current
CONDITIONS
MIN
TYP
MAX
MAX9_2/MAX9_3, IOUT = 1.8mA for C/E temp. ranges,
IOUT = 1.2mA for M temp. range
V- + 0.4
MAX9_1/MAX9_4, IOUT = 1.8mA for C/E temp. ranges,
IOUT = 1.2mA for M temp. range
GND + 0.4
V
VOUT = 11V
100
REFERENCE (MAX9_1/MAX982/MAX9_3/MAX9_4 ONLY)
X
C temp. range
E temp. range
Reference Voltage
M temp. range
TA = +25°C
C/E temp. ranges
Source Current
M temp. range
TA = +25°C
Sink Current
C/E temp. ranges
M temp. range
Voltage Noise
100Hz to 100kHz
UNITS
1.170
1.158
1.147
15
6
4
8
4
2
1.182
1.194
1.206
1.217
nA
V
25
µA
15
µA
100
µVRMS
ELECTRICAL CHARACTERISTICS: 3V OPERATION
(V+ = 5V, V- = GND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
POWER REQUIREMENTS
TA = +25°C
MAX9_1
2.4
C/E temp. ranges
M temp. range
4.8
TA = +25°C
MAX972
2.4
C/E temp. ranges
MAX982/
MAX9_3
MAX9_4
COMPARATOR
Input Offset Voltage
VCM = 1.5V
Input Leakage Current (IN-, IN+)
IN+ = IN- = 1.5V
Input Leakage Current (HYST)
Input Common-Mode Voltage Range
Common-Mode Rejection Ratio
Power-Supply Rejection Ratio
MAX9_1/MAX982/MAX9_3
4.8
TA = +25°C
C/E temp. ranges
M temp. range
TA = +25°C
C/E temp. ranges
M temp. range
C/E temp. ranges
M temp. range
3.4
4.3
5.2
5.8
7.2
6.2
8.0
10.5
±0.01
±10
±5
±40
±0.02
V-
V- to (V+ - 1.3V)
V+ = 2.5V to 11V
3.0
3.8
M temp. range
HYST = REF,
IN+ = (IN- + 100mV)
Supply Current
3.0
3.8
0.2
0.1
V+ - 1.3
1
1
µA
mV
nA
nA
V
mV/V
mV/V
_______________________________________________________________________________________
3
ELECTRICAL CHARACTERISTICS: 3V OPERATION (continued)
(V+ = 5V, V- = GND = 0V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)
PARAMETER
CONDITIONS
MIN
Voltage Noise
Hysteresis Input Voltage Range
100Hz to 100kHz
MAX9_1/MAX982/MAX9_3
Response Time
(high-to-low transition)
TA = +25°C, 100pF load,
1MΩ pull-up to V+
Response Time
(low-to-high transition) (Note 2)
TA = +25°C, 100pF load, 1MΩ pull-up to V+
Output Low Voltage
Output Leakage Current
TYP
MAX
UNITS
20
REF - 0.05
Overdrive = 10mV
Overdrive = 100mV
REF
µVRMS
V
12
4
µs
300
µs
MAX9_2/MAX9_3, IOUT = 0.8mA for C/E temp. ranges,
IOUT = 0.6mA for M temp. range
V- + 0.4
MAX9_1/MAX9_4, IOUT = 0.8mA for C/E temp. ranges,
IOUT = 0.6mA for M temp. range
GND + 0.4
V
VOUT = 11V
100
nA
1.194
1.206
1.217
V
REFERENCE
C temp. range
E temp. range
M temp. range
TA = +25°C
C/E temp. ranges
M temp. range
TA = +25°C
C/E temp. ranges
M temp. range
100Hz to 100kHz
Reference Voltage
Source Current
Sink Current
Voltage Noise
1.170
1.158
1.147
15
6
4
8
4
2
1.182
25
µA
15
µA
100
µVRMS
Note 1: MAX974/MAX984 comparators work below 2.5V; see Low-Voltage Operation section for more details.
Note 2: Low-to-high response time is the result of the 1MΩ pull-up and the 100pF capacitive load, based on three time constants.
A faster response time is achieved with a smaller RC.
__________________________________________Typical Operating Characteristics
(V+ = 5V, V- = GND, TA = +25°C, unless otherwise noted.)
V+ = 3V
1.5
1.0
0.5
0
1.180
SOURCE
1.175
1.170
1.165
V+ = 5V
OR
V+ = 3V
1.160
4
8
12
LOAD CURRENT (mA)
16
20
1.22
1.21
1.20
MILITARY TEMP. RANGE
MAX971/4-TOC3
1.185
EXTENDED TEMP. RANGE
COMMERCIAL
TEMP. RANGE
1.19
1.18
1.17
1.16
1.15
1.14
1.155
0
4
SINK
REFERENCE VOLTAGE (V)
2.0
1.190
MAX971/MAX973/MAX974
REFERENCE VOLTAGE vs. TEMPERATURE
MAX971/4-TOC2
V+ = 5V
REFERENCE OUTPUT VOLTAGE (V)
2.5
REFERENCE OUTPUT VOLTAGE vs.
OUTPUT LOAD CURRENT
MAX971/4-TOC1
OUTPUT VOLTAGE LOW
vs. LOAD CURRENT
VOL (V)
MAX971–MAX974/MAX981–MAX984
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
0
5
10
15
20
25
OUTPUT LOAD CURRENT (µA)
30
-60 -40 -20 0
20 40 60 80 100 120 140
TEMPERATURE (°C)
_______________________________________________________________________________________
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
MAX9_1
SUPPLY CURRENT vs.
TEMPERATURE
MAX972
SUPPLY CURRENT vs. TEMPERATURE
V+ = 5V, V- = - 5V
3.0
V+ = 3V, V- = 0V
3.5
V+ = 10V, V- = 0V
3.0
2.5
V+ = 5V, V- = 0V
-20
20
MAX971/4-TOC6
3.0
V+ = 3V, V- = 0V
60
100
140
2.0
-60
-20
20
100
60
140
-60
-20
20
60
100
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
MAX9_4
SUPPLY CURRENT vs. TEMPERATURE
MAX9_4
SUPPLY CURRENT vs.
LOW SUPPLY VOLTAGES
MAX9_1/MAX982/MAX9_3
HYSTERESIS CONTROL
8
V+ = 5V, V- = -5V
6
V+ = 5V, V- = 0V
4
1
0.1
60
OUTPUT LOW
100
-80
1.0
140
2.0
1.5
2.5
0
10
20
30
40
VREF -VHYST (mV)
MAX9_1/MAX972/MAX9_4
TRANSFER FUNCTION
RESPONSE TIME vs.
LOAD CAPACITANCE
RESPONSE TIME FOR VARIOUS
INPUT OVERDRIVES (VOHL)
3.0
2.5
2.0
1.5
14
VOHL
12
4
10mV
3
2
10
100mV
20mV
1
0
8
6
1.0
4
0.5
5
VOUT (V)
V- = 0V
16
VIN (mV)
10µF
MAX971/4 TOC11
4.0
V0
RESPONSE TIME (µs)
100k
18
MAX971/4-TOC10
+5V
50
MAX971/4-TOC12
TEMPERATURE (°C)
10k
3.5
NO CHANGE
SINGLE-SUPPLY VOLTAGE (V)
5.0
4.5
0
-20
-40
0.01
20
20
-60
3
-20
OUTPUT HIGH
40
V+ = 3V, V- = 0V
-60
140
MAX971/4 TOC9
MAX971/4-TOC8
80
60
IN+ - IN- (V)
9
SUPPLY CURRENT (µA)
IN+ = (IN- + 100mV)
5
10
MAX971/4-TOC7
10
SUPPLY CURRENT (µA)
V+ = 5V, V- = 0V
3.5
2.5
1.5
-60
4.0
V+ = 3V, V- = 0V
2.0
OUTPUT VOLTAGE (V)
4.5
2.0
V+ = 5V, V- = 0V
7
MAX971/4-TOC5
4.0
2.5
5.0
SUPPLY CURRENT (µA)
4.0
IN+ = (IN- + 100mV)
SUPPLY CURRENT (µA)
SUPPLY CURRENT (µA)
IN+ = IN- + 100mV
3.5
4.5
MAX971/4-TOC4
4.5
MAX982/MAX9_3
SUPPLY CURRENT vs. TEMPERATURE
50mV
100
0
2
0
-0.3
0.2
0.1
-0.2 -0.1
0
IN+ INPUT VOLTAGE (mV)
0.3
0
20
40
60
80
LOAD CAPACITANCE (nF)
100
-2
2
6
10
14
18
RESPONSE TIME (µs)
_______________________________________________________________________________________
5
MAX971–MAX974/MAX981–MAX984
____________________________Typical Operating Characteristics (continued)
(V+ = 5V, V- = GND, TA = +25°C, unless otherwise noted.)
____________________________Typical Operating Characteristics (continued)
(V+ = 5V, V- = GND, TA = +25°C, unless otherwise noted.)
100
-20mV
25
OUT CONNECTED TO V+
GND CONNECTED TO V20
SINK CURRENT (mA)
CURRENT (mA)
RPULL-UP = 10kΩ
MAX971/4-TOC14
100
MAX971/4-TOC13
1000
10
SHORT-CIRCUIT SINK CURRENT
vs. SUPPLY VOLTAGE
MAX924 RESPONSE TIME
AT LOW SUPPLY VOLTAGES
10
1
MAX971/4-TOC15
RESPONSE TIME
AT LOW SUPPLY VOLTAGES (VOHL)
RESPONSE TIME (µs)
MAX971–MAX974/MAX981–MAX984
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
15
10
5
-100mV
SINK CURRENT AT VOUT = 0.4V
0
0.1
1
1.0
1.2
1.4
1.6
1.8
2.0
2.2
2.4
1.0
SINGLE-SUPPLY VOLTAGE (V)
1.5
2.0
0
2.5
5
10
TOTAL SUPPLY VOLTAGE (V)
SINGLE-SUPPLY VOLTAGE (V)
____________________________________________________________Pin Descriptions
PIN
NAME
FUNCTION
MAX971
MAX981
MAX972
MAX982
MAX973
MAX983
1
—
—
—
GND
Ground. Connect to V- for single-supply operation. Output
transistor pulls to GND.
—
1
1
1
OUTA
Comparator A Open-Drain Output. Sinks current to V-.
2
2
2
2
V-
6
3
—
—
—
IN+
—
3
3
3
INA+
Negative Supply. Connect to ground for single-supply operation
(MAX9_1).
Noninverting Comparator Input
Noninverting Input of Comparator A
4
—
—
—
IN-
—
4
—
—
INA-
Inverting Comparator Input
Inverting Input of Comparator A
—
5
—
4
INB-
Inverting Input of Comparator B
—
6
4
—
INB+
Noninverting Input of Comparator B
5
—
5
5
HYST
Hysteresis Input. Connect to REF if not used. Input voltage range is
from VREF to VREF - 50mV.
6
—
6
6
REF
Reference Output. 1.182V with respect to V-.
7
7
7
7
V+
Positive Supply
8
—
—
—
OUT
—
8
8
8
OUTB
Comparator Output. Sinks current to GND.
Comparator B Open-Drain Output. Sinks current to V-.
_______________________________________________________________________________________
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
PIN
MAX974
MAX984
NAME
FUNCTION
1
OUTB
Comparator B Open-Drain Output. Sinks current to GND.
2
OUTA
Comparator A Open-Drain Output. Sinks current to GND.
3
V+
4
INA-
Positive Supply
Inverting Input of Comparator A
5
INA+
Noninverting Input of Comparator A
6
INB-
Inverting Input of Comparator B
7
INB+
Noninverting Input of Comparator B
8
REF
Reference Output. 1.182V with respect to V-.
9
V-
Negative Supply. Connect to ground for single-supply operation.
10
INC-
Inverting Input of Comparator C
11
INC+
Noninverting Input of Comparator C
12
IND-
Inverting Input of Comparator D
13
IND+
Noninverting Input of Comparator D
14
GND
Ground. Connect to V- for single-supply operation.
15
OUTD
Comparator D Open-Drain Output. Sinks current to GND.
16
OUTC
Comparator C Open-Drain Output. Sinks current to GND.
_______________________________________________________________________________________
7
MAX971–MAX974/MAX981–MAX984
_______________________________________________Pin Descriptions (continued)
MAX971–MAX974/MAX981–MAX984
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
_______________Detailed Description
Power-Supply and Input Signal Ranges
The MAX971–MAX974 and 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.
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
common-mode 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.
MAX9_3
1 OUTA
MAX972
1 OUTA
2 V3 INA+
4 INA-
OUTB 8
2 V-
V+ 7
3 INA+
INB+ 6
4 INB-
OUTB 8
V+ 7
REF 6
HYST 5
V-
INB- 5
Figure 1c. MAX973/MAX983 Functional Diagram (Window
Comparator)
Figure 1a. MAX972 Functional Diagram
1 OUTB
MAX9_4
2 OUTA
MAX982
1 OUTA
2 V-
OUTD 15
3 V+
GND 14
4 INA-
IND+ 13
5 INA+
IND- 12
6 INB-
INC+ 11
7 INB+
INC- 10
8 REF
V- 9
OUTB 8
V+ 7
3 INA+
REF 6
4 INB+
HYST 5
V-
Figure 1b. MAX982 Functional Diagram
8
OUTC 16
Figure 1d. MAX974/MAX984 Functional Diagram
_______________________________________________________________________________________
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
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 0°C to +70°C range. The REF output is typically
capable of sourcing 25µA and sinking 15µA. 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 300µV. 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.
IREF
Comparator Output
With 100mV of overdrive, propagation delay is typically
3µs. 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.
6
REF
2.5V TO 11V
7
V+
MAX9_1
MAX982
MAX9_3
R1
5
R2
HYST
V2
Figure 3. Programming the HYST Pin
_______________________________________________________________________________________
9
MAX971–MAX974/MAX981–MAX984
THRESHOLDS
IN+
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-.
MAX971–MAX974/MAX981–MAX984
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
__________Applications Information
V+
Hysteresis
RH
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 × IREF )

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. I REF values between 0.1µA and 4µA are
usually appropriate. If 2.4MΩ is chosen for R2 (IREF =
0.5µA), the equation for R1 and V HB can be
approximated as:
R1 (kΩ) = 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 pull-up resistor on the output.
10
RPULL-UP
VIN
V+
MAX9_4 V-
OUT
GND
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.
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.
______________________________________________________________________________________
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators


5.5
= 294k × 
− 1
 (1.182 + 0.005)

VIN
+5V
R3
1M
7
V+
3 INA+
1M
OUTA 1
5 HYST
R2
62.2k
R5
10k
R4
2.4M
= 1.068MΩ
6 REF
OUTB 8
4) Calculate R2. The undervoltage threshold should be
4.5V when VIN is falling. The design equation is as
follows:
(VREF − VH )
R2 = (R1 + R2 + R3) ×
− R1
VUTH
= (294k + 1.068M) ×
VOTH = 5.5V
VUTH = 4.5V
(1.182 − 0.005)
− 294k
4.5
= 62.2kΩ
Choose R2 = 61.9kΩ (1% standard value).
4 INBR1
294k
POWER GOOD
V-
MAX9_3
2
Figure 5. Window Detector
Battery Switchover Circuit
5) Calculate R3:
R3 = (R2 + R3) − R2
= 1.068M − 61.9k
= 1.006MΩ
Choose R3 = 1MΩ (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 ) ×
R1
= 5.474V
Undervoltage Threshold :
(R1 + R2 + R3)
VUTH = (VREF − VH ) ×
(R1 + R2)
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.
Level Shifter
Figure 7 shows a circuit to shift from bipolar ±5V inputs
to single-ended +5V outputs. The 10kΩ resistors
protect the comparator inputs, and do not materially
affect the circuit’s operation.
= 4.484V
where the hysteresis voltage VH = VREF ×
R5
.
R4
______________________________________________________________________________________
11
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 10MΩ can be used, but values in the
100kΩ to 1MΩ range are usually easier to deal with.
In this example, choose R1 = 294kΩ.
3) Calculate R2 + R3. The overvoltage threshold
should be 5.5V when V IN is rising. The design
equation is as follows:


VOTH
R2 + R3 = R1 × 
− 1
 VREF + VH

MAX971–MAX974/MAX981–MAX984
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
+5V
WALL
ADAPTER
+3.3V
3
V+
+9V DC
STEP-DOWN
REGULATOR
MAX974
MAX984
10k
+3.3V
LOGIC
SUPPLY
Q1
5 INA+
VINA
OUTA 2
4
INA-
1M
10k
7
V+
BATTERY
(4 CELLS)
7 INB+
VINB
OUTB 1
MAX973
MAX983
953k
10k
6 INB-
4 INB-
10k
OUTB 8
VINC
470k
11 INC+
LOW BATT
OUTC 16
10 INC-
1 OUTA
R1
110k
DC OK
10k
VIND
13 IND+
3 INA+
OUTD 15
REF 6
12 INDREF
20k
R2
47k
8
N.C.
HYST 5
V2
V9
GND
14
2.4M
-5V
Figure 7. Level Shifter: ±5V Input to Single-Ended +3.3V
Output
Figure 6. Battery Switchover Circuit
__________________________________________________________Pin Configurations
TOP VIEW
GND
1
8
OUT
V- 2
7
V+
6
REF
INA+ 3
5
HYST
INA- 4
IN+ 3
MAX971
MAX981
IN- 4
DIP/SO/µMAX
12
OUTA
OUTA
1
8
OUTB
V- 2
7
V+
6
INB+
INA+ 3
5
INB-
INB+ 4
MAX972
DIP/SO/µMAX
1
8
OUTB
V- 2
7
V+
6
REF
5
HYST
MAX982
DIP/SO/µMAX
______________________________________________________________________________________
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
TOP VIEW
OUTA
8
1
V- 2
INA+ 3
7
MAX973
MAX983
INB- 4
6
5
OUTB 1
16 OUTC
OUTA 2
15 OUTD
OUTB
V+ 3
V+
INA- 4
REF
INA+ 5
HYST
DIP/SO/µMAX
14 GND
MAX974
MAX984
13 IND+
12 IND-
INB- 6
11 INC+
INB+ 7
10 INC-
REF 8
9
V-
DIP/Narrow SO
__________________________________________Ordering Information (continued)
PART
TEMP. RANGE
PIN-PACKAGE
MAX971EPA
-40°C to +85°C
8 Plastic DIP
MAX971ESA
-40°C to +85°C
8 SO
MAX971MJA
-55°C to +125°C
8 CERDIP**
MAX972CPA
0°C to +70°C
8 Plastic DIP
MAX972CSA
0°C to +70°C
8 SO
MAX972CUA
MAX972C/D
MAX972EPA
MAX972ESA
MAX972MJA
MAX973CPA
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
0°C to +70°C
MAX973CSA
0°C to +70°C
MAX973CUA
MAX973C/D
MAX973EPA
MAX973ESA
MAX973MJA
MAX974CPE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
0°C to +70°C
MAX974CSE
MAX974C/D
MAX974EPE
MAX974ESE
MAX974MJE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
16 Narrow SO
Dice*
16 Plastic DIP
16 Narrow SO
16 CERDIP**
8 µMAX
Dice*
8 Plastic DIP
8 SO
8 CERDIP**
8 Plastic DIP
PART
TEMP. RANGE
MAX981CPA
MAX981CSA
MAX981CUA
MAX981EPA
MAX981ESA
MAX982CPA
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
PIN-PACKAGE
8 Plastic DIP
8 SO
8 µMAX
8 Plastic DIP
8 SO
8 Plastic DIP
MAX982CSA
0°C to +70°C
MAX982CUA
MAX982EPA
MAX982ESA
MAX983CPA
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
8 SO
8 SO
MAX983CSA
0°C to +70°C
8 µMAX
Dice*
8 Plastic DIP
8 SO
8 CERDIP**
16 Plastic DIP
MAX983CUA
MAX983EPA
MAX983ESA
MAX984CPE
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
0°C to +70°C
8 µMAX
8 Plastic DIP
8 SO
16 Plastic DIP
MAX984CSE
MAX984EPE
MAX984ESE
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
16 Narrow SO
16 Plastic DIP
16 Narrow SO
8 µMAX
8 Plastic DIP
8 SO
8 Plastic DIP
8 SO
* Dice are tested at TA = +25°C, DC parameters only.
** Contact factory for availability and processing to MIL-STD-883.
______________________________________________________________________________________
13
MAX971–MAX974/MAX981–MAX984
_____________________________________________Pin Configurations (continued)
MAX971–MAX974/MAX981–MAX984
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
___________________Chip Information
MAX971/MAX972/MAX973
TRANSISTOR COUNT: 164
SUBSTRATE CONNECTED TO V+
MAX974
TRANSISTOR COUNT: 267
SUBSTRATE CONNECTED TO V+
14
______________________________________________________________________________________
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
DIM
C
α
A
0.101mm
0.004 in
e
B
A1
L
A
A1
B
C
D
E
e
H
L
α
INCHES
MAX
MIN
0.044
0.036
0.008
0.004
0.014
0.010
0.007
0.005
0.120
0.116
0.120
0.116
0.0256
0.198
0.188
0.026
0.016
6°
0°
MILLIMETERS
MIN
MAX
0.91
1.11
0.10
0.20
0.25
0.36
0.13
0.18
2.95
3.05
2.95
3.05
0.65
4.78
5.03
0.41
0.66
0°
6°
21-0036D
E
H
8-PIN µMAX
MICROMAX SMALL-OUTLINE
PACKAGE
D
DIM
D
0°-8°
A
0.101mm
0.004in.
e
B
A1
E
C
H
L
Narrow SO
SMALL-OUTLINE
PACKAGE
(0.150 in.)
A
A1
B
C
E
e
H
L
INCHES
MAX
MIN
0.069
0.053
0.010
0.004
0.019
0.014
0.010
0.007
0.157
0.150
0.050
0.244
0.228
0.050
0.016
DIM PINS
D
D
D
8
14
16
MILLIMETERS
MIN
MAX
1.35
1.75
0.10
0.25
0.35
0.49
0.19
0.25
3.80
4.00
1.27
5.80
6.20
0.40
1.27
INCHES
MILLIMETERS
MIN MAX
MIN
MAX
0.189 0.197 4.80
5.00
0.337 0.344 8.55
8.75
0.386 0.394 9.80 10.00
21-0041A
______________________________________________________________________________________
15
MAX971–MAX974/MAX981–MAX984
_______________________________________________________Package Information
MAX971–MAX974/MAX981–MAX984
Ultra-Low-Power, Open-Drain,
Single/Dual-Supply Comparators
__________________________________________Package Information (continued)
D
E
DIM
E1
A
A1
A2
A3
B
B1
C
D1
E
E1
e
eA
eB
L
A3
A A2
L A1
0° - 15°
C
e
B1
B
eA
eB
D1
Plastic DIP
PLASTIC
DUAL-IN-LINE
PACKAGE
(0.300 in.)
INCHES
MAX
MIN
0.200
–
–
0.015
0.175
0.125
0.080
0.055
0.022
0.016
0.065
0.045
0.012
0.008
0.080
0.005
0.325
0.300
0.310
0.240
–
0.100
–
0.300
0.400
–
0.150
0.115
PKG. DIM PINS
P
P
P
P
P
N
D
D
D
D
D
D
8
14
16
18
20
24
INCHES
MIN
MAX
0.348 0.390
0.735 0.765
0.745 0.765
0.885 0.915
1.015 1.045
1.14 1.265
MILLIMETERS
MIN
MAX
–
5.08
0.38
–
3.18
4.45
1.40
2.03
0.41
0.56
1.14
1.65
0.20
0.30
0.13
2.03
7.62
8.26
6.10
7.87
2.54
–
7.62
–
–
10.16
2.92
3.81
MILLIMETERS
MIN
MAX
8.84
9.91
18.67 19.43
18.92 19.43
22.48 23.24
25.78 26.54
28.96 32.13
21-0043A
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.
16 __________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
© 1995 Maxim Integrated Products
Printed USA
is a registered trademark of Maxim Integrated Products.