MAXIM MAX9025, MAX9028 User Manual

19-3241; Rev 1; 6/11

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.

UCSP, 1.8V, Nanopower, Beyond-the-Rails

Comparators With/Without Reference

General Description

The MAX9025–MAX9028 nanopower comparators in
space-saving chip-scale (UCSP™) packages feature
Beyond-the-Rails™ inputs and are guaranteed to oper­ate down to +1.8V. The MAX9025/MAX9026 feature an
on-board 1.236V ±1% reference and draw an ultra-low
supply current of only 1µA, while the MAX9027/
MAX9028 (without reference) require just 0.6µA of supply
current. These features make the MAX9025–MAX9028
family of comparators ideal for all 2-cell battery­monitoring/management applications.

The unique design of the output stage limits supply­current surges while switching, virtually eliminating the
supply glitches typical of many other comparators. This
design also minimizes overall power consumption under
dynamic conditions. The MAX9025/MAX9027 have a
push-pull output stage that sinks and sources current.
Large internal-output drivers allow rail-to-rail output
swing with loads up to 5mA. The MAX9026/MAX9028
have an open-drain output stage that makes them suit­able for mixed-voltage system design. All devices are
available in the miniature 6-bump UCSP packages.

Refer to the MAX9117 data sheet for similar comparators
in 5-pin SC70 packages and the MAX9017 data sheet for
similar dual comparators in 8-pin SOT23 packages.

Applications

2-Cell Battery Monitoring/Management
Ultra-Low-Power Systems

Mobile Communications

Notebooks and PDAs

Sensing at Ground or Supply Line

Telemetry and Remote Systems

Medical Instruments

Selector Guide

PART

MAX9025 Yes Push-Pull 1.0

MAX9026 Yes Open-Drain 1.0

MAX9027 No Push-Pull 0.6

MAX9028 No Open-Drain 0.6

Typical Application Circuit appears at end of data sheet.

INTERNAL

REFERENCE

OUTPUT

TYPE

SUPPLY

CURRENT

)

(µA

Features

♦ Space-Saving UCSP Package (1mm x 1.52mm)

♦ Ultra-Low Supply Current

0.6µA (MAX9027/MAX9028)
1µA with Reference (MAX9025/MAX9026)

♦ Guaranteed to Operate Down to +1.8V

♦ Internal 1.236V ±1% Reference (MAX9025/MAX9026)

♦ Input Voltage Range Extends 200mV

Beyond-the-Rails

♦ CMOS Push-Pull Output with ±5mA Drive

Capability (MAX9025/MAX9027)

♦ Open-Drain Output Versions Available

(MAX9026/MAX9028)

♦ Crowbar-Current-Free Switching

♦ Internal Hysteresis for Clean Switching

♦ No Phase Reversal for Overdriven Inputs

Ordering Information

PART

MAX9025EBT+T -

MAX9026EBT+T -40°C to +85°C 6 UCSP ADC

MAX9027EBT+T -40°C to +85°C 6 UCSP ADD

MAX9028EBT+T -40°C to +85°C 6 UCSP ADE

+Denotes a lead(Pb)-free/RoHS-compliant package.

T = Tape and reel.

TEMP

RANGE

40°C to +85°C 6 UCSP ADB

BUMP­PACKAGE

TOP

MARK

Pin Configurations

TOP VIEW
(BUMPS ON BOTTOM)

B

1

IN+

MAX9025–

MAX9028

REF

2

)

(V

EE

IN-

3

V

OUT

V

A

CC

EE

MAX9025–MAX9028

Beyond-the-Rails and UCSP are trademarks of Maxim Integrated
Products, Inc.

________________________________________________________________ Maxim Integrated Products 1

( ) MAX9027/MAX9028 PINS

UCSP

MAX9025–MAX9028

UCSP, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS—MAX9025/MAX9026 (WITH REF)

(VCC= +5V, VEE= 0V, V

IN+

= V

REF

, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (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.

Supply Voltage (VCCto VEE)..................................................+6V

Voltage Inputs (IN+, IN-, REF) .........(VEE- 0.3V) to (VCC+ 0.3V)

Output Voltage

MAX9025/MAX9027....................(VEE- 0.3V) to (VCC+ 0.3V)

MAX9026/MAX9028..................................(VEE- 0.3V) to +6V

Current into Input Pins ........................................................20mA

Output Current..................................................................±50mA

Output Short-Circuit Duration .................................................10s

Continuous Power Dissipation (TA= +70°C)

6-Bump UCSP (derate 3.9mW/°C above +70°C)........308mW

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

PARAMETER

CONDITIONS

Supply Voltage Range V

CC

Inferred from the PSRR test 1.8 5.5 V
VCC = 1.8V 0.8 1.5

TA = +25°C 1.0 1.7Supply Current I

CC

VCC = 5V

2.2

µA

IN+ Voltage Range V

IN+

Inferred from output swing test

V

EE

-

0.2

V

CC

+

0.2

V

TA = +25°C 0.3 5

Input Offset Voltage V

OS

(Note 2)

10

mV

Input-Referred Hysteresis V

HB

(Note 3) 4 mV
TA = +25°C

1

Input Bias Current I

B

TA = T

MIN

to T

MAX

2

nA

Power-Supply Rejection Ratio PSRR VCC = 1.8V to 5.5V 0.1 1

TA = +25°C

350

M AX 9025, V

C C

= 5V ,

I

S OU R C E

= 6m A

450

TA = +25°C 56 200

Output Voltage Swing High

V

CC

-

V

OH

M AX 9025, V

C C

=

300

mV

TA = +25°C

350

V

C C

= 5V ,

I

S I N K

= 6m A

450

TA = +25°C 57 200

Output Voltage Swing Low V

OL

V

C C

= 1.8V ,

I

S IN K

= 1m A

300

mV

Output Leakage Current I

LEAK

MAX9026 only, VO = 5.5V

1µA

VCC = 5V 35

Sourcing, VO = V

EE

VCC = 1.8V 3
VCC = 5V 33

Output Short-Circuit Current I

SC

Sinking, VO = V

CC

VCC = 1.8V 3

mA

VCC = 1.8V 7

High-to-Low Propagation Delay
(Note 4)

t

PD-

V

CC

= 5V 6

µs

SYMBOL

MIN TYP MAX UNITS

TA = T

MIN

to T

MAX

TA = T

MIN

to T

MAX

= T

MIN

MIN

MIN

MIN

to T

to T

to T

to T

MAX

MAX

MAX

MAX

TA = T

= 1m A

S OU RC E

T

A

TA = T

TA = T

1.8V , I

0.15

250

250

0.001

mV/V

MAX9025–MAX9028

UCSP, 1.8V, Nanopower, Beyond-the-Rails

Comparators With/Without Reference

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS—MAX9027/MAX9028 (WITHOUT REF)

(VCC= +5V, VEE= 0V, VCM= 0V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

ELECTRICAL CHARACTERISTICS—MAX9025/MAX9026 (WITH REF) (continued)

(VCC= +5V, VEE= 0V, V

IN+

= V

REF

, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

VCC = 1.8V 11

MAX9025 only

V

CC

= 5V 28

VCC = 1.8V 12

Low-to-High Propagation Delay
(Note 4)

t

PD+

MAX9026 only,
R

PULLUP

= 100kΩ

V

CC

= 5V 31

µs

Rise Time t

RISE

MAX9025 only, CL = 15pF 1.6 µs

Fall Time t

FALL

CL = 15pF 0.2 µs

Power-Up Time t

ON

1.2 ms

TA = +25°C

Reference Voltage V

REF

TA = T

MIN

to T

MAX

V

Reference Voltage Temperature
Coefficient

TC

REF

40

°C

BW = 10Hz to 100kHz 29

Reference Output Voltage Noise

E

N

C

REF

= 1nF

BW = 10Hz to 6kHz 60

Reference Line Regulation

∆V

REF

/

∆V

CC

VCC = 1.8V to 5.5V 0.5

Reference Load Regulation

∆V

REF

/

∆I

OUT

∆I

OUT

= 0nA to 100nA

mV/

nA

1.224 1.236 1.248

1.205 1.267

0.03

ppm/

µV

mV/V

RMS

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Supply Voltage Range V

Input Common-Mode
Voltage Range

Input Offset Voltage V

Input-Referred Hysteresis V

Input Bias Current I

Power-Supply Rejection Ratio PSRR VCC = 1.8V to 5.5V 0.1 1 mV/V
Common-Mode Rejection Ratio CMRR (VEE - 0.2V) ≤ VCM ≤ (VCC + 0.2V) 0.5 3 mV/V

CC

CC

V

CM

OS

HB

B

Inferred from the PSRR test 1.8 5.5 V
VCC = 1.8V 0.45 0.75

VCC = 5V

Inferred from the CMRR test

-0.2V ≤ VCM ≤
+ 0.2V)

(V
(Note 2)

-0.2V ≤ VCM ≤ (VCC + 0.2V) (Note 3) 4 mV

TA = +25°C 0.15 1
TA = T

CC

to T

MIN

MAX

TA = +25°C 0.6 1.0Supply Current I

= T

MIN

to T

MAX

V

EE

T

A

0.2

TA = +25°C 0.3 5

= T

MIN

to T

MAX

T

A

µA

1.25

-

VCC +

0.2

V

mV

10

2

nA

MAX9025–MAX9028

UCSP, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS—MAX9027/MAX9028 (WITHOUT REF) (continued)

(VCC= +5V, VEE= 0V, VCM= 0V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.) (Note 1)

Note 1: All specifications are 100% tested at T

A

= +25°C. Specification limits over temperature (TA= T

MIN

to T

MAX

) are guaranteed

by design, not production tested.

Note 2: V

OS

is defined as the center of the hysteresis band at the input.

Note 3: The hysteresis-related trip points are defined as the edges of the hysteresis band, measured with respect to the center of

the band (i.e., V

OS

) (Figure 2).

Note 4: Specified with an input overdrive (V

OVERDRIVE

) of 100mV, and load capacitance of CL= 15pF. V

OVERDRIVE

is defined
above and beyond the offset voltage and hysteresis of the comparator input. For the MAX9025/MAX9026, reference voltage
error should also be added.

PARAMETER

CONDITIONS

UNITS

TA = +25°C

MAX9027 only, VCC =
5V, I

SOURCE

= 5mA

TA = +25°C58

Output Voltage Swing High

MAX9028 only, VCC =

mV

TA = +25°C

VCC = 5V,
I

SINK

= 5mA

TA = +25°C56

Output Voltage Swing Low V

OL

VCC = 1.8V,
I

SINK

= 1mA

mV

Output Leakage Current I

LEAK

MAX9028 only, VO = 5.5V

1µA

VCC = 5V 35

Sourcing, VO = V

EE

VCC = 1.8V 3
VCC = 5V 33

Output Short-Circuit Current I

SC

Sourcing, VO = V

CC

VCC = 1.8V 3

mA

VCC = 1.8V 16

High-to-Low Propagation Delay
(Note 4)

t

PD-

VCC = 5V 14

µs

VCC = 1.8V 15

MAX9027 only

V

CC

= 5V 40

VCC = 1.8V,

16

Low-to-High Propagation Delay
(Note 4)

t

PD+

MAX9028 only

V

CC

= 5V,

45

µs

Rise Time t

RISE

MAX9027 only, CL = 15pF 1.6 µs

Fall Time t

FALL

CL = 15pF 0.2 µs

Power-Up Time t

ON

1.2 ms

SYMBOL

VCC - V

OH

1.8V, I

SOURCE

= 1mA

TA = T

= T

T

A

TA = T

TA = T

MIN

MIN

MIN

MIN

to T

to T

to T

to T

MIN TYP MAX

191 400

MAX

MAX

191 400

MAX

MAX

0.001

500
200
300

500
200
300

R

R

PULLUP

PULLUP

= 100kΩ

= 100kΩ

MAX9025/MAX9026

SUPPLY CURRENT vs. SUPPLY VOLTAGE

MAX9025-28 toc01

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (nA)

4.53.52.5

800

1000

1200

600

1.5 5.5

TA = +85°C

TA = +25°C

TA = -40°C

MAX9025-28 toc02

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (nA)

4.53.52.5

400

500

600

700

800

300

1.5 5.5

MAX9027/MAX9028

SUPPLY CURRENT vs. SUPPLY VOLTAGE

TA = +85°C

TA = +25°C

T

A

= -40°C

MAX9025-28 toc03

TEMPERATURE (°C)

SUPPLY CURRENT (nA)

603510-15

800

1000

1200

600

-40 85

MAX9025/MAX9026

SUPPLY CURRENT vs. TEMPERATURE

VCC = 5V

VCC = 1.8V

VCC = 3V

MAX9025-28 toc04

TEMPERATURE (°C)

SUPPLY CURRENT (nA)

603510-15

400

500

600

700

800

300

-40 85

VCC = 5V

VCC = 3V

MAX9027/MAX9028

SUPPLY CURRENT vs. TEMPERATURE

VCC = 1.8V

OUTPUT VOLTAGE LOW

vs. SINK CURRENT

MAX9025-28 toc07

SINK CURRENT (mA)

OUTPUT VOLTAGE LOW (mV)

8642

200

400

600

800

0

010

VCC = 5V

VCC = 3V

VCC = 1.8V

MAX9025-28 toc05

TRANSITION FREQUENCY (kHz)

SUPPLY CURRENT (µA)

101

5

10

15

20

25

30

35

40

0

0.1 100

MAX9025/MAX9026

SUPPLY CURRENT vs. OUTPUT

TRANSITION FREQUENCY

VCC = 5V

VCC = 3V

VCC = 1.8V

MAX9025-28 toc06

TRANSITION FREQUENCY (kHz)

SUPPLY CURRENT (µA)

101

5

10

15

20

25

30

35

40

0

0.1 100

MAX9027/MAX9028

SUPPLY CURRENT vs. OUTPUT

TRANSITION FREQUENCY

VCC = 5V

VCC = 3V

VCC = 1.8V

OUTPUT VOLTAGE LOW

vs. SINK CURRENT

MAX9025-28 toc08

SINK CURRENT (mA)

OUTPUT VOLTAGE LOW (mV)

8642

200

400

600

800

0

010

TA = +85°C

TA = +25°C

TA = -40°C

MAX9025/MAX9027

OUTPUT VOLTAGE HIGH vs. SOURCE CURRENT

MAX9025-28 toc09

SOURCE CURRENT (mA)

OUTPUT VOLTAGE HIGH (V

CC

- V

OH

, mV)

8642

200

400

600

800

0

010

VCC = 5V

VCC = 3V

VCC = 1.8V

MAX9025–MAX9028

UCSP, 1.8V, Nanopower, Beyond-the-Rails

Comparators With/Without Reference

_______________________________________________________________________________________ 5

Typical Operating Characteristics

(VCC= +5V, V

EE

= 0V, CL= 15pF, V

OVERDRIVE

= 100mV, TA= +25°C, unless otherwise noted.)

Typical Operating Characteristics (continued)

(VCC= +5V, V

EE

= 0V, CL= 15pF, V

OVERDRIVE

= 100mV, TA= +25°C, unless otherwise noted.)

MAX9025–MAX9028

UCSP, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference

6 _______________________________________________________________________________________

MAX9025/MAX9027

OUTPUT VOLTAGE HIGH vs. SOURCE CURRENT

MAX9025-28 toc10

SOURCE CURRENT (mA)

OUTPUT VOLTAGE HIGH (V

CC

- V

OH

, mV)

8642

200

400

600

800

0

010

TA = +85°C

TA = +25°C

TA = -40°C

SHORT-CIRCUIT SINK

CURRENT vs. TEMPERATURE

MAX9025-28 toc11

TEMPERATURE (°C)

SHORT-CIRCUIT SINK CURRENT (mA)

603510-15

10

20

30

40

0

-40 85

VCC = 5V

VCC = 3V

VCC = 1.8V

V

OUT

= V

CC

MAX9025/MAX9027 SHORT-CIRCUIT SOURCE

CURRENT vs. TEMPERATURE

MAX9025-28 toc12

TEMPERATURE (°C)

SHORT-CIRCUIT SINK CURRENT (mA)

603510-15

10

20

30

40

0

-40 85

VCC = 5V

VCC = 3V

VCC = 1.8V

V

OUT

= V

EE

OFFSET VOLTAGE

vs. TEMPERATURE

MAX9025-28 toc13

TEMPERATURE (°C)

OFFSET VOLTAGE (mV)

603510-15

0.3

0.5

0.8

1.0

0

-40 85

VCC = 5V

VCC = 3V

VCC = 1.8V

HYSTERESIS VOLTAGE

vs. TEMPERATURE

MAX9025-28 toc14

TEMPERATURE (°C)

HYSTERESIS VOLTAGE (mV)

603510-15

2.5

3.0

3.5

4.0

2.0

-40 85

VCC = 5V

VCC = 3V

VCC = 1.8V

-1.000

-0.600

0.200

-0.200

0.600

1.000

-0.5 1.50.5 2.5 3.5 4.5 5.5

INPUT BIAS CURRENT

vs. INPUT BIAS VOLTAGE

MAX9025-28 toc15

INPUT BIAS VOLTAGE (IN-) (V)

INPUT BIAS CURRENT (IN-) (nA)

IN+ = 2.5V

MAX9025/MAX9026

REFERENCE VOLTAGE vs. TEMPERATURE

MAX9025-28 toc16

TEMPERATURE (°C)

REFERENCE VOLTAGE (V)

603510-15

1.2340

1.2350

1.2360

1.2370

1.2330

-40 85

VCC = 5V

VCC = 3V

VCC = 1.8V

MAX9025/MAX9026

REFERENCE VOLTAGE vs. TEMPERATURE

MAX9025-28 toc17

TEMPERATURE (°C)

REFERENCE VOLTAGE (V)

603510-15

1.233

1.235

1.237

1.239

1.231

-40 85

5 DEVICES

MAX9025/MAX9026

REFERENCE VOLTAGE

vs. SUPPLY VOLTAGE

MAX9025-28 toc18

SUPPLY VOLTAGE (V)

REFERENCE VOLTAGE (V)

4.53.52.5

1.235

1.236

1.237

1.238

1.234

1.5 5.5

Typical Operating Characteristics (continued)

(VCC= +5V, V

EE

= 0V, CL= 15pF, V

OVERDRIVE

= 100mV, TA= +25°C, unless otherwise noted.)

MAX9025–MAX9028

UCSP, 1.8V, Nanopower, Beyond-the-Rails

Comparators With/Without Reference

_______________________________________________________________________________________ 7

40

30

20

10

0

0.01 10.1 10 100

MAX9025/MAX9027

PROPAGATION DELAY (t

PD+

)

vs. CAPACITIVE LOAD

MAX9025-28 toc23

CAPACITIVE LOAD (nF)

t

PD+

(µs)

VCC = 5V

VCC = 3V

VCC = 1.8V

0

10

20

30

40

50

60

70

80

01020304050

PROPAGATION DELAY (t

PD-

)

vs. INPUT OVERDRIVE

MAX9025-28 toc24

INPUT OVERDRIVE (mV)

t

PD-

(µs)

VCC = 5V

VCC = 3V

VCC = 1.8V

0

20

10

40

30

50

60

02010 30 40 50

MAX9025/MAX9027

PROPAGATION DELAY (t

PD+

)

vs. INPUT OVERDRIVE

MAX9025-28 toc25

INPUT OVERDRIVE (mV)

t

PD+

(µs)

VCC = 5V

VCC = 3V

VCC = 1.8V

MAX9026/MAX9028

PROPAGATION DELAY (t

PD+

)

vs. PULLUP RESISTANCE

MAX9025-28 toc26

PULLUP RESISTANCE (kΩ)

t

PD+

(µs)

1000100

25

50

75

100

125

150

175

200

0

10 10000

VCC = 5V

VCC = 3V

VCC = 1.8V

20µs/div

PROPAGATION DELAY (VCC = 5V)

+100mV

MAX9025 toc27

-100mV

OUT
2V/div

0V

IN+

MAX9025/MAX9026

REFERENCE VOLTAGE

vs. REFERENCE CURRENT

MAX9025-28 toc19

REFERENCE CURRENT (nA)

REFERENCE VOLTAGE (V)

500-50

1.234

1.236

1.238

1.240

1.232

-100 100

VCC = 5V

VCC = 3V

VCC = 1.8V

PROPAGATION DELAY (t

PD-

)

vs. TEMPERATURE

MAX9025-28 toc20

TEMPERATURE (°C)

t

PD-

(µs)

603510-15

5

10

15

20

0

-40 85

VCC = 5V

VCC = 3V

VCC = 1.8V

MAX9025/MAX9027

PROPAGATION DELAY (t

PD+

)

vs. TEMPERATURE

MAX9025-28 toc21

TEMPERATURE (°C)

t

PD+

(µs)

603510-15

10

20

30

40

50

0

-40 85

VCC = 5V

VCC = 3V

VCC = 1.8V

20

15

10

5

0

0.01 10.1 10 100

PROPAGATION DELAY (t

PD-

)

vs. CAPACITIVE LOAD

MAX9025-28 toc22

CAPACITIVE LOAD (nF)

t

PD-

(µs)

VCC = 5V

VCC = 3V

VCC = 1.8V

Typical Operating Characteristics (continued)

(VCC= +5V, V

EE

= 0V, CL= 15pF, V

OVERDRIVE

= 100mV, TA= +25°C, unless otherwise noted.)

MAX9025–MAX9028

UCSP, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference

8 _______________________________________________________________________________________

20µs/div

PROPAGATION DELAY (VCC = 1.8V)

+100mV

MAX9025 toc29

-100mV

OUT
1V/div

0V

IN+

200µs/div

1kHz FREQUENCY RESPONSE

(V

CC

= 5V)

+100mV

MAX9025 toc30

-100mV

OUT
2V/div

0V

IN+

20µs/div

PROPAGATION DELAY (VCC = 3V)

+100mV

MAX9025 toc28

-100mV

OUT
1V/div

0V

IN+

1ms/div

REFERENCE RESPONSE TO SUPPLY

VOLTAGE TRANSIENT (C

REF

= 10nF)

REF
200mV/div

MAX9025 toc32

V

CC

1V/div

1.8V

5V

40µs/div

POWER-UP/POWER-DOWN RESPONSE

V

CC

MAX9025 toc33

0V

OUT
2V/div

0V

2V/div

20µs/div

10kHz FREQUENCY RESPONSE

(V

CC

= 1.8V)

+100mV

MAX9025 toc31

-100mV

OUT
1V/div

0V

IN+

MAX9025–MAX9028

UCSP, 1.8V, Nanopower, Beyond-the-Rails

Comparators With/Without Reference

_______________________________________________________________________________________ 9

Functional Diagrams

MAX9025
MAX9026

IN+

OUT

V

CC

V

EE

IN-

REF

1.236V

MAX9027
MAX9028

IN+

OUT

V

CC

V

EE

IN-

REF

Detailed Description

The MAX9025/MAX9026 feature an on-board 1.236V
±1% reference, yet draw an ultra-low supply current of

1.0µA. The MAX9027/MAX9028 (without reference)
consume just 0.6µA of supply current. All four devices
are guaranteed to operate down to +1.8V. Their com­mon-mode input voltage range extends 200mV
beyond-the-rails. Internal hysteresis ensures clean out­put switching, even with slow-moving input signals.
Large internal output drivers allow rail-to-rail output
swing with up to ±5mA loads.

The output stage employs a unique design that mini­mizes supply-current surges while switching, virtually
eliminating the supply glitches typical of many other
comparators. The MAX9025/MAX9027 have a push-pull
output stage that sinks as well as sources current. The

MAX9026/MAX9028 have an open-drain output stage
that can be pulled beyond VCCto a maximum of 5.5V
above VEE. These open-drain versions are ideal for
implementing wire-OR output logic functions.

Input Stage Circuitry

The input common-mode voltage range extends from
V

EE

- 0.2V to VCC+ 0.2V. These comparators operate
at any differential input voltage within these limits. Input
bias current is typically ±0.15nA if the input voltage is
between the supply rails. Comparator inputs are pro­tected from overvoltage by internal ESD protection
diodes connected to the supply rails. As the input volt­age exceeds the supply rails, these ESD protection
diodes become forward biased and begin to conduct.

Output Stage Circuitry

The MAX9025–MAX9028 contain a unique break­before-make output stage capable of rail-to-rail opera­tion with up to ±5mA loads. Many comparators
consume orders of magnitude more current during
switching than during steady-state operation. However,
with this family of comparators, the supply-current
change during an output transition is extremely small.
In the Typical Operating Characteristics, the Supply
Current vs. Output Transition Frequency graphs show
the minimal supply-current increase as the output
switching frequency approaches 1kHz. This character­istic reduces the need for power-supply filter capaci­tors to reduce glitches created by comparator
switching currents. In battery-powered applications,
this characteristic results in a substantial increase in
battery life.

PIN

FUNCTION

A2 A2

Comparator Output

A3 A3, B2

Negative Supply Voltage

B1 B1

Comparator Noninverting
Input

B2 —

1.236V Reference Output

A1 A1

Positive Supply Voltage

B3 B3 IN-

Comparator Inverting
Input

Pin Description

MAX9025/

MAX9026

MAX9027/

MAX9028

NAME

OUT

V

EE

IN+

REF

V

CC

MAX9025–MAX9028

UCSP, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference

10 ______________________________________________________________________________________

Reference (MAX9025/MAX9026)

The MAX9025–MAX9028s’ internal +1.236V reference
has a typical temperature coefficient of 40ppm/°C over
the full -40°C to +85°C temperature range. The reference
is a very-low-power bandgap cell, with a typical 35kΩ
output impedance. REF can source and sink up to
100nA to external circuitry. For applications needing
increased drive, buffer REF with a low input-bias current
op amp such as the MAX4162. Most applications require
no REF bypass capacitor. For noisy environments or fast
VCCtransients, connect a 1nF to 10nF ceramic capacitor
from REF to GND.

Applications Information

Low-Voltage, Low-Power Operation

The MAX9025–MAX9028 are ideally suited for use with
most battery-powered systems. Table 1 lists a variety of
battery types, capacities, and approximate operating
times for the MAX9025–MAX9028, assuming nominal
conditions.

Internal Hysteresis

Many comparators oscillate in the linear region of opera­tion because of noise or undesired parasitic feedback.
This tends to occur when the voltage on one input is
equal or very close to the voltage on the other input. The
MAX9025–MAX9028 have internal 4mV hysteresis to
counter parasitic effects and noise.

The hysteresis in a comparator creates two trip points:
one for the rising input voltage (V

THR

) and one for the

falling input voltage (V

THF

) (Figure 2). The difference
between the trip points is the hysteresis (VHB). When
the comparator’s input voltages are equal, the hystere­sis effectively causes one comparator input to move

quickly past the other, thus taking the input out of the
region where oscillation occurs. Figure 2 illustrates the
case in which IN- has a fixed voltage applied, and IN+
is varied. If the inputs were reversed, the figure would
be the same, except with an inverted output.

Adding External Hysteresis

In applications requiring more than the internal 4mV
hysteresis of the MAX9025–MAX9028, additional hys­teresis can be added with external components.
Because the MAX9025–MAX9028 are intended for very
low-power systems, care should be taken to minimize
power dissipation in the additional circuitry.

Regardless of which approach is taken, the external
hysteresis will be V

CC

dependent. Over the full discharge
range of battery-powered systems, the hysteresis can
change as much as 40%. This must be considered
during design.

BANDGAP

REF

V

EE

V

CC

Figure 1. MAX9025/MAX9026 Voltage Reference Output
Equivalent Circuit

Table 1. Battery Applications Using MAX9025–MAX9028

BATTERY

TYPE

RECHARGEABLE

V

FRESH

(V)

V

END-OF-LIFE

(V)

CAPACITY,

AA SIZE

(mA-H)

MAX9025/MAX9026

OPERATING TIME

(hr)

MAX9027/MAX9028

OPERATING TIME

(hr)

Alkaline
(2 Cells)

No 3.0 1.8 2000 1.8 x 10

6

2.8 x 10

6

Nickel­Cadmium
(2 Cells)

Yes 2.4 1.8 750 680,000 1.07 x 10

6

Lithium-Ion
(1 Cell)

Yes 3.5 2.7 1000 0.9 x 10

6

1.4 x 10

6

Nickel-Metal­Hydride
(2 Cells)

Yes 2.4 1.8 1000 0.9 x 10

6

1.4 x 10

6

MAX9025–MAX9028

UCSP, 1.8V, Nanopower, Beyond-the-Rails

Comparators With/Without Reference

______________________________________________________________________________________ 11

THRESHOLDS

OUT

IN+

IN-

V

HB

HYSTERESIS

BAND

V

THF

V

THR

Figure 2. Threshold Hysteresis Band

V

CC

MAX9027

OUT

R

S

R

FB

VCC/2

VIN

Figure 3. MAX9025/MAX9027 External Hysteresis

Simplest Circuit

The simplest circuit for adding external hysteresis is
shown in Figure 3. In this example, the hysteresis is
defined by:

where RSis the source resistance and RFBis the feed­back resistance. Because the comparison threshold is
1/2 VCC, the MAX9027 was chosen for its push-pull out­put and lack of reference. This provides symmetrical
hysteresis around the threshold.

Output Considerations

In most cases, the push-pull outputs of the
MAX9025/MAX9027 are best for external hysteresis.
The open-drain output of the MAX9026/MAX9028 can
be used, but the effect of the feedback network on the
actual output high voltage must be considered.

Component Selection

Because the MAX9025–MAX9028 are intended for very
low power-supply systems, the highest impedance cir­cuits should be used wherever possible. The offset
error due to input-bias current is proportional to the
total impedance seen at the input. For example, select­ing components for Figure 3, with a target of 50mV hys­teresis, a 5V supply, and choosing an R

FB

of 10MΩ
gives RSas 100kΩ. The total impedance seen at IN+ is
therefore 10MΩ || 100kΩ, or 99kΩ. The maximum IBof
the MAX9025–MAX9028 is 2nA; therefore, the error due
to source impedance is less than 400µV.

Asymmetrical Hysteresis

When the input threshold is not set at 1/2 VCC, the hys­teresis added to the input threshold will not be symmet­rical. This is typical of the MAX9025/MAX9026 where
the internal reference is usually used as the threshold.
If the asymmetry is unacceptable, it can be corrected
by adding resistors to the circuit.

Board Layout and Bypassing

Power-supply bypass capacitors are not typically need­ed, but use 100nF bypass capacitors close to the
device’s supply pins when supply impedance is high,
supply leads are long, or excessive noise is expected
on the supply lines. Minimize signal trace lengths to
reduce stray capacitance. A ground plane and surface­mount components are recommended. If the REF pin is
decoupled, use a new low-leakage capacitor.

Zero-Crossing Detector

Figure 4 shows a zero-crossing detector application.
The MAX9027’s inverting input is connected to ground,
and its noninverting input is connected to a 100mV

P-P

signal source. As the signal at the noninverting input
crosses 0V, the comparator’s output changes state.

Logic-Level Translator

The Typical Application Circuit shows an application
that converts 5V logic to 3V logic levels. The MAX9028
is powered by the +5V supply voltage, and the pullup
resistor for the MAX9028’s open-drain output is con­nected to the +3V supply voltage. This configuration
allows the full 5V logic swing without creating overvolt­age on the 3V logic inputs. For 3V to 5V logic-level
translations, simply connect the +3V supply voltage to
VCCand the +5V supply voltage to the pullup resistor.

Hysteresis

R

R

V

S

FB

CC

=×

MAX9025–MAX9028

UCSP, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference

12 ______________________________________________________________________________________

UCSP Applications Information

For the latest application details on UCSP construction,
dimensions, tape carrier information, printed circuit board
techniques, bump-pad layout, and recommended reflow
temperature profiles, 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.

Chip Information

TRANSISTOR COUNT: 209
PROCESS: BiCMOS

MAX9028

IN-

2MΩ

2MΩ

R

PULLUP

3V (5V)
LOGIC OUT

OUT

V

CC

+5V (+3V)

+3V (+5V)

V

EE

5V (3V) LOGIC IN

IN+

LOGIC-LEVEL
TRANSLATOR

Typical Application Circuit

MAX9027

IN+

OUT

V

CC

100mV

P-P

V

CC

V

EE

IN-

Figure 4. Zero-Crossing Detector

UCSP, 1.8V, Nanopower, Beyond-the-Rails

Comparators With/Without Reference

Package Information

For the latest package outline information and land patterns, 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 pertains to the
package regardless of RoHS status.

PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.

6 UCSP B6+1

21-0097

Refer to Application Note 1891

6L, UCSP.EPS

MAX9025–MAX9028

PACKAGE OUTLINE, 3x2 UCSP

21-0097

______________________________________________________________________________________ 13

1

G

1

UCSP, 1.8V, Nanopower, Beyond-the-Rails
Comparators With/Without Reference

Revision History

REVISION

NUMBER

0 5/04 Initial release. —

1 6/11 Added information for lead-free versions 1

REVISION

DATE

MAX9025–MAX9028

DESCRIPTION

PAGES

CHANGED

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.

14

____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

© 2011 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.