General Description
The MAX9644/MAX9645/MAX9646 are small, single com-
parators, ideal for a wide variety of portable electronics
applications such as cell phones, media players, and
notebooks that have extremely tight board space and
power constraints. These comparators are offered in both
a miniature 4-bump UCSP™ package with a 1mm x 1mm
footprint (as small as two 0402 resistors) and a
5-pin SOT23 package.
The ICs feature an input voltage range of -0.3V to
+5.5V, independent of supply voltage. These devices
maintain high impedance at the inputs even when pow-
ered down (VCC or VREF = 0V). They also feature inter-
nal filtering to provide high RF immunity.
The ICs have an internal 0.2V reference. These devices
feature either a push-pull or an open-drain output. They
consume only 700nA (max) supply current and operate
down to VCC = 1V over the extended -40°C to +85°C tem-
perature range.
Applications
Cell Phones
Portable Media Players
Electronic Toys
Notebook Computers
Portable Medical Devices
Features
oTiny, 1mm x 1mm x 0.6mm 4-Bump UCSP
Footprint = Two 0402 Resistors
Also Available in a 5-Pin SOT23 Package
oUltra-Low Operating Current (700nA max)
o-0.3V to +5.5V Input Voltage Range
oInternal 0.2V Reference Trimmed to 1% Accuracy
o15µs Propagation Delay
o-40°C to +85°C Extended Temperature Range
MAX9644/MAX9645/MAX9646
Low-Power Comparators with Precision
Reference in 4-Bump UCSP
________________________________________________________________
Maxim Integrated Products
1
19-5803; Rev 1; 10/11
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
EVALUATION KIT
AVAILABLE
Ordering Information
PART PIN-PACKAGE TOP MARK
MAX9644EBS+G45 4 UCSP +AGL
MAX9644EUK+ 5 SOT23 +AFJN
MAX9645EBS+G45 4 UCSP +AGM
MAX9645EUK+ 5 SOT23 +AFJO
MAX9646EBS+G45 4 UCSP +AGN
MAX9646EUK+ 5 SOT23 +AFJP
Note: All devices are specified over the extended -40°C to
+85°C operating temperature range.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
G45
= Protective die coating.
UCSP is a trademark of Maxim Integrated Products, Inc.
PART REFERENCE VOLTAGE (V) INPUT OUTPUT
MAX9644 0.2 Noninverting Open drain
MAX9645 0.2 Inverting Open drain
MAX9646 0.2 Noninverting Push-pull
Selector Guide
MAX9644/MAX9645/MAX9646
Low-Power Comparators with Precision
Reference in 4-Bump UCSP
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = 3.3V, RPULLUP = 10kΩto VPULLUP = 3.3V for MAX9644/MAX9645, TA= -40°C to +85°C. Typical values at TA= +25°C, unless
otherwise noted.) (Note 1)
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.
VCC, REF, IN to GND................................................-0.3V to +6V
OUT to GND (MAX9644/MAX9645)..........................-0.3V to +6V
OUT to GND (MAX9646 only) .................-0.3V to + (VCC + 0.3V)
Output Short-Circuit Current Duration ....................................10s
Input Current into Any Terminal........................................±20mA
Continuous Power Dissipation
4-Bump UCSP (derate 3.0mW/°C above +70°C) .......238 mW
5-Pin SOT23 (derate 3.9mW/°C above +70°C)...........312 mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Bump Temperature (soldering) Reflow............................+235°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
DC CHARACTERISTICS
Input Voltage Range VIN Guaranteed by IIN test -0.3 +5.5 V
Input Bias Current IIN VIN = 0.2V to 5.5V (Note 2) 0.06 15 nA
Input Leakage Current IIN_SHDN VCC = 0, VIN = 5.5V (Note 2) < 0.1 15 nA
ISINK = 50µA, VCC = 1.0V 0.03 0.2
ISINK = 200µA, VCC = 1.2V 0.08 0.20
ISINK = 500µA, VCC = 1.8V 0.13 0.23
ISINK = 0.75mA, VCC = 3.3V 0.14 0.3
Output Voltage Low VOL
ISINK = 1.2mA, VCC = 5.5V 0.19 0.5
V
ISOURCE = 15µA, VCC = 1.0V V
C C
- 0.08V V
C C
- 0.2V
ISOURCE = 40µA, VCC = 1.2V V
C C
- 0.08V V
C C
- 0.20V
ISOURCE = 180µA, VCC = 1.8V V
C C
- 0.15V V
C C
- 0.23V
ISOURCE = 0.3mA, VCC = 3.3V V
C C
- 0.13V V
C C
- 0.3V
Output Voltage High
(MAX9464 Only) VOH
ISOURCE = 0.75mA, VCC = 5.5V V
C C
- 0.24V V
C C
- 0.5V
V
Output Leakage Current
(MAX9644/MAX9645 Only) IOUT_LEAKAGE OUT = high, VPULLUP = 5.5V
(Note 2) < 0.1 15 nA
AC CHARACTERISTICS
Propagation Delay tPD VOVERDRIVE = ±100mV (Note 3) 15 µs
Fall Time tFCL = 10pF 14 ns
Rise Time tRCL = 10pF, MAX9646 only 30 ns
REFERENCE VOLTAGE
MAX964_EBS+ 200
Input Threshold (Note 4) VREF MAX964_EUK+ 199 mV
TA = +25°C -1 +1
Input Threshold Error
(Note 4) Delta-VREF TA = -40°C to +85°C -3.5 +3.5 %
Input Threshold Hysteresis VHYS TA = -40°C to +85°C (Note 5) ±0.9 mV
REF Tempco VREF_TEMPCO (Note 6) 6 µV/°C
Power-Supply Rejection
Ratio PSRR VCC = 1.0V to 5.5V 40 53 dB
MAX9644/MAX9645/MAX9646
Low-Power Comparators with Precision
Reference in 4-Bump UCSP
_______________________________________________________________________________________ 3
Note 1: All devices are 100% production tested at TA = +25°C. Temperature limits are guaranteed by design.
Note 2: Too small to be measured in an ATE test environment. Only gross test to catch failures is implemented.
Note 3: Overdrive is defined as the voltage above or below the switching points.
Note 4: Guaranteed by ATE and/or bench characterization over temperature. VREF is the average of the trip points.
Note 5: Hysteresis is half the input voltage difference between the two switching points.
Note 6: Includes reference error along with comparator offset voltage error.
ELECTRICAL CHARACTERISTICS
(VCC = 3.3V, RPULLUP = 10kΩto VPULLUP = 3.3V for MAX9644/MAX9645, TA= -40°C to +85°C. Typical values at TA= +25°C, unless
otherwise noted.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
POWER SUPPLY
Supply Voltage VCC Guaranteed by VOL/VOH tests 1.0 5.5 V
VCC = 1.0V 0.4 0.7
Supply Current ICC VCC = 5.5V 0.6 1.1 µA
Power-Up Time tON 3ms
Typical Operating Characteristics
(VCC = 3.3V, VREF = 1.8V, RPULLUP = 10kΩto VPULLUP = 3.3V for MAX9644/MAX9645, GND = 0, TA= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX9644 toc01
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (nA)
54321
200
400
600
800
1000
0
06
+85°C
-40°C
+25°C
SUPPLY CURRENT
vs. OUTPUT TRANSITION FREQUENCY
MAX9644 toc02
OUTPUT TRANSITION FREQUENCY (kHz)
SUPPLY CURRENT (µA)
110
10
100
1
0.1 100
VCC = 5V
VCC = 3.3V
VCC = 1.8V
OUTPUT VOLTAGE LOW
vs. SINK CURRENT
MAX9644 toc03
SINK CURRENT (mA)
OUTPUT VOLTAGE LOW (V)
62
0.5
1.0
0.1
0.6
0.4
0.9
0.3
0.8
0.2
0.7
0
048
VREF = 3.3V
VREF = 1.8V
VREF = 5V
INPUT BIAS CURRENT
vs. INPUT BIAS VOLTAGE
MAX9644 toc05
INPUT BIAS VOLTAGE (V)
INPUT BIAS CURRENT (nA)
-5
5
0
-10
-15
-20
0 0.20 0.25 0.300.05 0.10 0.15
VCC = 3.3V
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX9644 toc11
TEMPERATURE (°C)
REFERENCE VOLTAGE (mV)
201.6
202.0
201.8
201.4
201.2
201.0
201.7
201.9
201.5
201.3
201.1
-40 8510 60-15 35
VCC = 3.3V
REFERENCE VOLTAGE
vs. SUPPLY VOLTAGE
MAX9644 toc07
SUPPLY VOLTAGE (V)
REFERENCE VOLTAGE (mV)
200.2
201.0
200.6
199.8
199.4
199.0
200.4
200.8
200.0
199.6
199.2
1.0 5.02.5 3.0 4.54.01.5 2.0 3.5
MAX9644/MAX9645/MAX9646
Low-Power Comparators with Precision
Reference in 4-Bump UCSP
4 _______________________________________________________________________________________
Typical Operating Characteristics
(VCC = 3.3V, VREF = 1.8V, RPULLUP = 10kΩto VPULLUP = 3.3V for MAX9644/MAX9645, GND = 0, TA= +25°C, unless otherwise noted.)
PROPAGATION DELAY
vs. TEMPERATURE
MAX9644 toc08
TEMPERATURE (°C)
PROPAGATION DELAY (µs)
14
17
10
15
16
13
12
11
9
-40 -15 60 853510
VCC = 3.3V
VCC = 1.8V
VCC = 5V
VOD = ±100mV
PROPAGATION DELAY
vs. INPUT OVERDRIVE
MAX9644 toc09
INPUT OVERDRIVE (mV)
PROPAGATION DELAY (µs)
50
80
10
60
40
30
20
70
0
0 100 150 25020050
VCC = 3.3V
VCC = 1.8V
VCC = 5V
OUTPUT VOLTAGE HIGH
vs. SOURCE CURRENT (MAX9646)
MAX9644 toc04
SOURCE CURRENT (mA)
OIUTPUT VOLTAGE HIGH (VCC - VOH, V)
0.5
1.0
0.1
0.6
0.4
0.9
0.3
0.8
0.2
0.7
0
01.51.0 2.5 3.00.5 2.0
VCC = 3.3V
VCC = 1.8V
VCC = 5V
MAX9644/MAX9645/MAX9646
Low-Power Comparators with Precision
Reference in 4-Bump UCSP
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(VCC = 3.3V, VREF = 1.8V, RPULLUP = 10kΩto VPULLUP = 3.3V for MAX9644/MAX9645, GND = 0, TA= +25°C, unless otherwise noted.)
PROPAGATION DELAY AT VCC = 3.3V
MAX9644 toc10
100
µ
s/div
0V
0.1V
0.3V
IN+
100mV/div
OUT
2V/div
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX9644 toc11
REFERENCE VOLTAGE (mV)
201.6
202.0
201.8
201.4
201.2
201.0
201.7
201.9
201.5
201.3
201.1
-40 8510 60-15 35
VCC = 3.3V
POWER-SUPPLY REJECTION
FOR NO FALSE TRIGGERING
MAX9644 toc14
FREQUENCY (Hz)
TRIP POINT (mV)
100k100
200
206
194
202
196
204
198
10 10k1k 1M
VCC = 3.3V + 100mVP-P
UPPER TRIP POINT
LOWER TRIP POINT
POWER-UP/POWER-DOWN RESPONSE
MAX9644 toc12
1ms/div
0V
0V
VCC
2V/div
OUT
2V/div
VIN = 0.3V
VCC = 3.3V
OUTPUT RESPONSE TO
SUPPLY VOLTAGE TRANSIENT
MAX9644 toc13
1ms/div
0V
0V
0V
3V
3.2V VCC
200mV/div
OUT
2V/div
OUT
2V/div
OUT
2V/div
VIN = VTH + 20mV
VIN = VTH + 10mV
VIN = VTH + 1mV
MAX9644/MAX9645/MAX9646
Low-Power Comparators with Precision
Reference in 4-Bump UCSP
6 _______________________________________________________________________________________
Pin Description
PIN
UCSP SOT23 NAME FUNCTION
A1 5 OUT Comparator Output. The MAX9644/MAX9645 have open-drain outputs. The MAX9646 has a
push-pull output.
A2 4 IN Comparator Input. The MAX9644/MAX9646 have noninverting inputs. The MAX9645 has
inverting inputs.
B1 1 VCC Power-Supply Voltage. Bypass to ground with a 0.1µF bypass capacitor.
B2 2, 3 GND Ground
MAX9644
MAX9645
MAX9646
MAX9644
MAX9645
MAX9646
A1
UCSP SOT23
TOP VIEW (BUMPS ON BOTTOM)
A2
B1 B2
IN
GND
OUT
VCC
1+
3
2
5
4
VCC
GND
OUT
IN
GND
Pin Configuration
MAX9644/MAX9645/MAX9646
Low-Power Comparators with Precision
Reference in 4-Bump UCSP
_______________________________________________________________________________________ 7
Detailed Description
The MAX9644/MAX9645/MAX9646 are extremely small
comparators ideal for compact, low-current, and low-
voltage applications.
The ICs consume only 400nA (typ). The low-voltage
operating capability of the operating current makes
these devices extremely attractive to long-life battery-
operated devices—these applications can now use a
single digital power-supply rail to power the new gener-
ation of microcontrollers (which can be down to 0.9V).
All parts are available in a tiny 4-bump UCSP, which is
only 0.6mm tall and occupies a 1mm x 1mm footprint
and a 5-pin SOT23.
Input Stage Circuitry
Noninverting inputs are available on the MAX9644/
MAX9646 and inverting inputs are available on the
MAX9645.
The MAX9644/MAX9645/MAX9646 incorporate an inno-
vative input stage architecture that allows their input
voltage to exceed VCC by several volts (limited only by
the
Absolute Maximum Ratings
). This is unlike tradition-
al comparators that have an input ESD diode clamp
between the input and VCC, limiting this maximum over-
voltage to about 0.3V. The ICs architecture maintains a
high input impedance to input signals even when the
device power-supply voltage is completely turned off
(VCC or REF taken to 0V). This greatly benefits flexible
power-saving schemes to be easily implemented in
advanced battery-operated devices. On-chip filtering
provides immunity from any RF noise being picked up by
input traces. These devices feature an internal tempera-
ture-compensated, low-power 0.2V reference voltage.
Output Stage Structure
The MAX9644/MAX9645 have open-drain outputs that
allow them to interface to logic circuitry running from
supply voltages other than the one supplied to the part.
These devices require an external pullup resistor or
current source for proper operation. Many microcon-
troller digital inputs ports can be readily programmed to
include these.
The MAX9646 has a push-pull output stage that can
both sink and source current, eliminating the need for
an external pullup resistor. In this case, the MAX9646
uses the microcontroller’s power supply as VCC.
Applications Information
Bypassing REF/VCC
Place a 0.1µF capacitor between REF or VCC and
GND as close as possible to the device. During a
switching event, all comparators draw a current spike
from their power-supply rails. This current spike is
minimized by the use of an internal break-before-make
design.
Hysteresis Operation
The ICs feature internal hysteresis for noise immunity
and glitch-free operation. If additional hysteresis is
needed, an external positive feedback network can be
easily implemented on the MAX9644 and MAX9646 non-
inverting input devices. Additional external hysteresis is
not possible on the MAX9645 because the noninverting
input of the comparator is not externally accessible.
PART INPUT VOLTAGE CONDITIONS ACTION AT OUTPUT
VIN > 0.2V External pullup resistor pulls output high.
MAX9644 VIN < 0.2V Output asserts low.
VIN > 0.2V Output asserts low.
MAX9645 VIN < 0.2V External pullup resistor pulls output high.
VIN > 0.2V Output asserts high.
MAX9646 VIN < 0.2V Output asserts low.
Table 1. How Devices Behave Under Various Input Voltage Conditions
MAX9644/MAX9645/MAX9646
Low-Power Comparators with Precision
Reference in 4-Bump UCSP
8 _______________________________________________________________________________________
Typical Operating Circuits
MAX9644
IN MICROCONTROLLER
INTERNAL
PULLUP
VDD
VCC = 1.0V TO 5.5V
I/OOUT
0.2V REF
MAX9646
IN MICROCONTROLLER
VDD
VCC = 1.0V TO 5.5V
I/OOUT
0.2V REF
MAX9645
IN MICROCONTROLLER
INTERNAL
PULLUP
VDD
VCC = 1.0V TO 5.5V
I/OOUT
0.2V REF
Chip Information
PROCESS: BiCMOS
MAX9644/MAX9645/MAX9646
Low-Power Comparators with Precision
Reference in 4-Bump UCSP
_______________________________________________________________________________________ 9
Package Information
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing per-
tains to the package regardless of RoHS status.
PACKAGE TYPE PACKAGE CODE DOCUMENT NO. LAND PATTERN NO.
4 UCSP B4+1 21-0117 Refer to Application Note 1891
5 SOT23 U5+2 21-0057 90-0174
MAX9644/MAX9645/MAX9646
Low-Power Comparators with Precision
Reference in 4-Bump UCSP
10 ______________________________________________________________________________________
Package Information (continued)
For the latest package outline information and land patterns (footprints), go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing per-
tains to the package regardless of RoHS status.
MAX9644/MAX9645/MAX9646
Low-Power Comparators with Precision
Reference in 4-Bump UCSP
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 ____________________
11
© 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Revision History
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 3/11 Initial release —
1 10/11 Updated Features section 1
