Micropower, Ultra-Small, Single/Dual/Quad,

Single-Supply Comparators

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Detailed Description

The MAX9021/MAX9022/MAX9024 are single/dual/

quad, low-cost, low-power comparators that consume

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:

age at which the comparator switches its output from

Pin Description

PIN

MAX9021

MAX9022

MAX9024

NAME

FUNCTION

1

——

IN+

Comparator Noninverting Input

2

4

11

Negative Supply Voltage

3

——

IN-

Comparator Inverting Input

4

——

OUT

Comparator Output

58

4

Positive Supply Voltage. Bypass with a 0.1µF capacitor to GND.

—

1

1

OUTA

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

7

OUTB

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