General Description
The MAX9021/MAX9022/MAX9024 single/dual/quad
comparators are optimized for low-power consumption
while still providing a fast output response. They are
designed for single-supply applications from 2.5V to
5.5V, but can also operate from dual supplies. These
comparators have a 3µs propagation delay and con-
sume 2.8µA of supply current per comparator over the
-40°C to +125°C operating temperature range. The
combination of low-power, single-supply operation
down to 2.5V, and ultra-small footprint makes these
devices ideal for portable applications.
The MAX9021/MAX9022/MAX9024 have 4mV of built-in
hysteresis to provide noise immunity and prevent oscil-
lations even with a slow-moving input signal. The input
common-mode range extends from the negative supply
to within 1.1V of the positive supply. The design of the
comparator-output stage substantially reduces switch-
ing current during output transitions, eliminating power-
supply glitches.
The MAX9021 single comparator is available in tiny 5-
pin SC70 and SOT23 packages. The MAX9022 dual
comparator is available in 8-pin SOT23, µMAX®, and
SO packages, and the MAX9024 quad comparator is
available in 14-pin TSSOP and SO packages.
Features
♦Low-Cost Solution Available in Space-Saving
SC70 Packages (Half the Size of SOT23)
♦Low 2.8µA Supply Current
♦3µs Propagation Delay
♦Internal 4mV Comparator Hysteresis
♦Comparator Output Swings Rail-to-Rail
♦2.5 to 5.5V Single-Supply Voltage Range
♦No Phase Reversal for Overdriven Inputs
♦Space-Saving Packages
5-Pin SC70 (MAX9021)
8-Pin SOT23 (MAX9022)
8-Pin µMAX (MAX9022)
14-Pin TSSOP (MAX9024)
MAX9021/MAX9022/MAX9024
Micropower, Ultra-Small, Single/Dual/Quad,
Single-Supply Comparators
________________________________________________________________ Maxim Integrated Products 1
TOP VIEW
VSS
OUTIN-
15V
DD
IN+
MAX9021
SC70/SOT23
2
34
INB-
INB+VSS
1
2
8
7
VDD
OUTBINA-
INA+
OUTA
S0T23/µMAX/SO
3
4
6
5
MAX9022
14
13
12
11
10
9
8
1
2
3
4
5
6
7
OUTD
IND-
IND+
VSS
VDD
INA+
INA-
OUTA
MAX9024
INC+
INC-
OUTCOUTB
INB-
INB+
TSSOP/SO
Pin Configurations
19-1842; Rev 2; 1/07
Ordering Information
Battery-Powered
Portable Systems
Mobile Communications
Sensor-Signal Detection
Photodiode Preamps
Digital Line Receivers
Keyless Entry Systems
Threshold Detectors/
Discriminators
Typical Application Circuit appears at end of data sheet.
PA RT
TEMP RANGE
PIN-
PACKAGE
PKG
CODE
MAX9021AXK-T -40°C to +125°C
5 SC70-5 X5-1
MAX9021AUK-T -40°C to +125°C5 SOT23-5
U5-1
MAX9022AKA-T -40°C to +125°C8 SOT23-8
K8-5
MAX9022AUA
-40°C to +125°C
8 µMAX U8-1
MAX9022ASA
-40°C to +125°C
8 SO S8-2
MAX9024AUD
-40°C to +125°C14 TSSOP
U14-1
MAX9024ASD
-40°C to +125°C
14 SO S14-2
µMAX is a registered trademark of Maxim Integrated Products, Inc.
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.
Applications
MAX9021/MAX9022/MAX9024
Micropower, Ultra-Small, Single/Dual/Quad,
Single-Supply Comparators
2_______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.
Supply Voltage (VDD to VSS)....................................-0.3V to +6V
Voltage Inputs (IN+, IN- to VSS). ................-0.3V to (VDD + 0.3V)
Differential Input Voltage (IN+ to IN-)....................................6.6V
Current into Input Pins ......................................................±20mA
Output Short-Circuit Duration ..................2s to Either VDD or VSS
Current into Any Pin ............................................................20mA
Continuous Power Dissipation (TA= +70°C)
5-Pin SC70 (derate 3.1mW/°C above +70°C)...............247mW
5-Pin SOT23 (derate 7.1mW/°C above +70°C).............571mW
8-Pin SOT23 (derate 9.1mW/°C above +70°C).............727mW
8-Pin µMAX (derate 4.5mW/°C above +70°C) ..............362mW
8-Pin SO (derate 5.88mW/°C above +70°C).................471mW
14-Pin TSSOP (derate 9.1mW/°C above +70°C) ..........727mW
14-Pin SO (derate 8.3mW/°C above +70.......................667mW
Operating Temperature Range
Automotive Application...................................-40°C to +125°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
UNITS
Operating Voltage Range VDD Guaranteed by PSRR test 2.5 5.5 V
S up p l y C ur r ent P er C om p ar ator IDD 2.8 5 µA
Input Offset Voltage VOS (Note 2) ±1±8mV
Input Offset Voltage
Temperature Coefficient
TCVOS
±1
µV/°C
Hysteresis (Note 3) 4 mV
Input Bias Current IBIAS 380nA
Input Offset Current IOS ±2±60 nA
Common-Mode Voltage Range VCM Guaranteed by CMRR test
VSS VDD - 1.1
V
C om m on- M od e Rej ecti on Rati o
CMRR
V
S S
≤ V
C M
≤ ( V
D D
- 1.1V ) , V
D D
= 5.5V 70 100 d B
Power-Supply Rejection Ratio
PSRR
VDD = 2.5V to 5.5V 60 80 dB
ISOURCE = 10µA 2
VOH = VDD - VOUT,
(VIN+ - VIN-) ≥ 20mV ISOURCE = 4mA
160
400
ISINK = 10µA 2
Output-Voltage Swing
VOL, VOH
VOL = VOUT - VSS,
(VIN- - VIN+) ≥ 20mV ISINK = 4mA
180
400
mV
Output Short-Circuit Current ISC 50 m A
VOD = 10mV 8
Propagation Delay
t
p
d+, t
p
d-
RL = 10kΩ,
CL = 15pF (Note 4) VOD = 100mV 3 µs
Rise and Fall Time tR, tFRL = 10kΩ, CL = 15pF (Note 5) 20 ns
Power-On Time RL = 10kΩ, CL = 15pF
150
ns
Maximum Capacitive Load CLNo sustained oscillations
150
pF
Note 1: All devices are production tested at 25°C. All temperature limits are guaranteed by design.
Note 2: Comparator Input Offset is defined as the center of the hysteresis zone.
Note 3: Hysteresis is defined as the difference of the trip points required to change comparator output states.
Note 4: VOD is the overdrive voltage beyond the offset and hysteresis-determined trip points.
Note 5: Rise and fall times are measured between 10% and 90% at OUT.
ELECTRICAL CHARACTERISTICS
(VDD = 5V, VSS = 0, VCM = 0, TA= -40°C to +125°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)
MAX9021/MAX9022/MAX9024
Micropower, Ultra-Small, Single/Dual/Quad,
Single-Supply Comparators
_______________________________________________________________________________________ 3
Typical Operating Characteristics
(VDD = 5V, VSS = 0, VCM = 0, RL= 10kΩ, CL= 15pF, VOD = 100mV, TA= +25°C, unless otherwise noted.)
3.0
2.9
2.8
2.7
2.6
24356
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX9021/2/4 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
2.5
2.6
2.8
2.7
2.9
3.0
-50 0-25 25 50 75 100 125
SUPPLY CURRENT vs. TEMPERATURE
MAX9021/2/4 toc02
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
1000
1
0.01 1 1000
SUPPLY CURRENT
vs. OUTPUT TRANSITION FREQUENCY
10
100
MAX9021/2/4 toc03
OUTPUT TRANSITION FREQUENCY (kHz)
SUPPLY CURRENT (µA)
0.1 10 100
0
0.4
0.2
0.8
0.6
1.2
1.0
1.4
-50 0 25-25 50 75 100 125
INPUT OFFSET VOLTAGE
vs. TEMPERATURE
MAX9021/2/4 toc04
TEMPERATURE (°C)
INPUT OFFSET VOLTAGE (mV)
0
100
200
300
400
500
0426810
OUTPUT HIGH VOLTAGE
vs. SOURCE CURRENT
MAX9021/2/4 toc05
SOURCE CURRENT (mA)
(VDD - VOUT) (mV)
0
100
200
300
400
500
0426810
OUTPUT LOW VOLTAGE
vs. SINK CURRENT
MAX9021/2/4 toc06
SINK CURRENT (mA)
OUTPUT LOW VOLTAGE (mV)
40
45
55
50
60
65
-50 0-25 25 50 75 100 125
OUTPUT SHORT-CIRCUIT CURRENT
vs. TEMPERATURE
MAX9021/2/4 toc07
TEMPERATURE (°C)
OUTPUT SHORT-CIRCUIT CURRENT (mA)
SOURCE CURRENT
SINK CURRENT
0
1
2
3
4
5
0
PROPAGATION DELAY vs. CAPACITIVE LOAD
(VDD = 2.7V)
MAX9021/2/4 toc08
CAPACITIVE LOAD (pF)
PROPAGATION DELAY (µs)
tPD-
tPD+
500 1000 1500 2000
0
1
2
3
4
5
PROPAGATION DELAY vs. CAPACITIVE LOAD
(VDD = 5V)
MAX9021/2/4 toc09
CAPACITIVE LOAD (pF)
PROPAGATION DELAY (µs)
tPD-
0 500 1000 1500 2000
tPD+
MAX9021/MAX9022/MAX9024
Micropower, Ultra-Small, Single/Dual/Quad,
Single-Supply Comparators
4_______________________________________________________________________________________
Typical Operating Characteristics (continued)
(VDD = 5V, VSS = 0, VCM = 0, RL= 10kΩ, CL= 15pF, VOD = 100mV, TA= +25°C, unless otherwise noted.)
0
1
3
2
4
5
-50 0-25 25 50 75 100 125
PROPAGATION DELAY
vs. TEMPERATURE
MAX9021/2/4 toc10
TEMPERATURE (°C)
PROPAGATION DELAY (µs)
tPD-
tPD+
0
2
1
5
4
3
8
7
6
9
0406020 80 100 120 140
PROPAGATION DELAY
vs. INPUT OVERDRIVE VOLTAGE
MAX9021/2/4 toc11
INPUT OVERDRIVE VOLTAGE (mV)
PROPAGATION DELAY (µs)
tPD+
tPD-
PROPAGATION DELAY (tPD+)
MAX9021/2/4 toc12
1µs/div
IN+
100mV/div
VOUT
2.5V/div
PROPAGATION DELAY (tPD-)
MAX9021/2/4 toc13
1µs/div
IN+
100mV/div
VOUT
2.5V/div
OUTPUT SWITCHING CURRENT, RISING
MAX9021/2/4 toc14
20µs/div
IN+ - IN-
200mV/div
VOUT
5V/div
SWITCHING
CURRENT
400µA/div
OUTPUT SWITCHING CURRENT, FALLING
MAX9021/2/4 toc15
20µs/div
IN+ - IN-
200mV/div
VOUT
5V/div
SWITCHING
CURRENT
400µA/div
10kHz RESPONSE
(VOD = 10mV)
MAX9021/2/4 toc16
10µs/div
IN+ - IN-
10mV/div
OUT
2.5V/div
10kHz RESPONSE
(VOD = 100mV)
MAX9021/2/4 toc17
10µs/div
IN+ - IN-
100mV/div
OUT
2.5V/div
POWER-UP TIME
MAX9021/2/4 toc18
2µs/div
VDD
2.5V/div
VOUT
2.5V/div
MAX9021/MAX9022/MAX9024
Micropower, Ultra-Small, Single/Dual/Quad,
Single-Supply Comparators
_______________________________________________________________________________________ 5
Detailed Description
The MAX9021/MAX9022/MAX9024 are single/dual/
quad, low-cost, low-power comparators that consume
only 2.8µA and provide a propagation delay, tPD, typi-
cally 3µs. They have an operating-supply voltage from
2.5V to 5.5V when operating from a single supply and
from ±1.25V to ±2.75V when operating from dual power
supplies. Their common-mode input voltage range
extends from the negative supply to within 1.1V of the
positive supply. Internal hysteresis ensures clean out-
put switching, even with slow-moving input signals.
Applications Information
Adding Hysteresis
Hysteresis extends the comparator’s noise margin by
increasing the upper threshold and decreasing the
lower threshold. A voltage-divider from the compara-
tor’s output sets the trip voltage. Therefore, the trip volt-
age is related to the output voltage.
These comparators have 4mV internal hysteresis.
Additional hysteresis can be generated with two resis-
tors, using positive feedback (Figure 1). Use the follow-
ing procedure to calculate resistor values:
1) Find the trip points of the comparator using these for-
mulas:
VTH = VREF + ((VDD - VREF)R2) / (R1 + R2)
VTL = VREF(1 - (R2 / (R1 + R2))
where VTH is the threshold voltage at which the com-
parator switches its output from high to low as VIN
rises above the trip point. VTL is the threshold volt-
age at which the comparator switches its output from
low to high as VIN drops below the trip point.
Pin Description
PIN
M A X9 0 2 1
M A X9 0 2 2
M A X9 0 2 4
NAME FUNCTION
1— — IN+ Comparator Noninverting Input
2411V
SS Negative Supply Voltage
3— — IN- Comparator Inverting Input
4— —OUT Comparator Output
58 4 V
DD Positive Supply Voltage. Bypass with a 0.1µF capacitor to GND.
—1 1OUTA Comparator A Output
—2 2 INA- Comparator A Inverting Input
—3 3 INA+ Comparator A Noninverting Input
—5 5 INB+ Comparator B Noninverting Input
—6 6 INB- Comparator B Inverting Input
—7 7OUTB Comparator B Output
—— 8 OUTC Comparator C Output
—— 9 INC- Comparator C Inverting Input
—— 10 INC+ Comparator C Noninverting Input
—— 12 IND+ Comparator D Noninverting Input
—— 13 IND- Comparator D Inverting Input
—— 14 OUTD Comparator D Output
MAX9021/MAX9022/MAX9024
Micropower, Ultra-Small, Single/Dual/Quad,
Single-Supply Comparators
6_______________________________________________________________________________________
2) The hysteresis band will be:
VHYS = VTH - VTL = VDD(R2 / (R1 + R2))
3) In this example, let VDD = 5V and VREF = 2.5V.
VTH = 2.5V + 2.5V(R2 / (R1 + R2))
and
VTL = 2.5V[(1 - (R2 / (R1 + R2))]
4) Select R2. In this example, we will choose 1kΩ.
5) Select VHYS. In this example, we will choose 50mV.
6) Solve for R1.
VHYS = VDD(R2 / (R1 + R2))
0.050V = 5(1000Ω/(R1 + 1000Ω)) V
where R1 ≈100kΩ, VTH = 2.525V, and VTL = 2.475V.
The above-described design procedure assumes rail-
to-rail output swing. If the output is significantly loaded,
the results should be corrected.
Board Layout and Bypassing
Use 100nF bypass as a starting point. Minimize signal
trace lengths to reduce stray capacitance. Minimize the
capacitive coupling between IN- and OUT. For slow-
moving input signals (rise time > 1ms), use a 1nF
capacitor between IN+ and IN-.
Biasing for Data Recovery
Digital data is often embedded into a bandwidth and
amplitude-limited analog path. Recovering the data can
be difficult. Figure 2 compares the input signal to a
time-averaged version of itself. This self-biases the
threshold to the average input voltage for optimal noise
margin. Even severe phase distortion is eliminated from
the digital output signal. Be sure to choose R1 and C1
so that:
fCAR >> 1 / (2πR1C1)
where fCAR is the fundamental carrier frequency of the
digital data stream.
MAX9021
OUT
IN+
IN-
R2
R1
VIN
VREF
VDD
VSS
VDD
Figure 1. Additional Hysteresis
MAX9021
OUT
IN+
IN-
10kΩ
0.1µF
VDD
VIN
VSS
VDD
Figure 2. Time Averaging of the Input Signal for Data Recovery
MAX9021/MAX9022/MAX9024
Micropower, Ultra-Small, Single/Dual/Quad,
Single-Supply Comparators
_______________________________________________________________________________________ 7
SC70, 5L.EPS
PACKAGE OUTLINE, 5L SC70
21-0076 1
1
D
MAX9021
OUT
IN+
IN-
VIN
VDD
VDD
VREF
R1
R2
RL
0.1µF
Typical Application Circuit Chip Information
MAX9021 TRANSISTOR COUNT: 106
MAX9022 TRANSISTOR COUNT: 212
MAX9024 TRANSISTOR COUNT: 424
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.)
MAX9021/MAX9022/MAX9024
Micropower, Ultra-Small, Single/Dual/Quad,
Single-Supply Comparators
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.
8_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
©2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
SOT23, 8L .EPS SOT-23 5L .EPS
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.)
Revision History
Pages changed at Rev 2: 1, 2, 6, 7, 8