Ultra-Low-Power, Open-Drain,

Single/Dual-Supply Comparators

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9

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 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.

OUTA

V-

INA+

INA-

OUTB

V+

INB+

INB-

MAX972

1 (A1)

2 (C2)

3 (C1)

4 (B1)

8 (A3)

7 (A2)

6 (C3)

5 (B3)

( ) BUMPS FOR THE UCSP

Figure 1a. MAX972 Functional Diagram

OUTA

V-

INA+

INB-

OUTB

V+

REF

HYST

MAX9_3

1

2

3

4

8

7

6

5

V-

Figure 1c. MAX973/MAX983 Functional Diagram

(Window Comparator)

OUTA

V-

INA+

INB+

OUTB

V+

REF

HYST

MAX982

1

2

3

4

8

7

6

5

V-

Figure 1b. MAX982 Functional Diagram

OUTA

V+

INA-

INA+

OUTD

GND

IND+

IND-

MAX9_4

2

3

4

5

15

14

13

12

16

11

10

9

1

6

7

8

OUTB

INB-

INB+

REF

OUTC

INC+

INC-

V-

Figure 1d. MAX974/MAX984 Functional Diagram