MAX9021(2001) Просмотр технического описания (PDF) - Maxim Integrated

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MAX9021
(Rev.:2001)

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

Maxim Integrated 

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

Single-Supply Comparators

MAX9021

1

2

3

4

5

—

—

—

—

—

—

—

—

—

—

—

—

PIN

MAX9022

—

4

—

—

8

1

2

3

5

6

7

—

—

—

—

—

—

MAX9024

—

11

—

—

4

1

2

3

5

6

7

8

9

10

12

13

14

Pin Description

NAME

IN+

VSS

IN-

OUT

VDD

OUTA

INA-

INA+

INB+

INB-

OUTB

OUTC

INC-

INC+

IND+

IND-

OUTD

FUNCTION

Comparator Noninverting Input

Negative Supply Voltage

Comparator Inverting Input

Comparator Output

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

Comparator A Output

Comparator A Inverting Input

Comparator A Noninverting Input

Comparator B Noninverting Input

Comparator B Inverting Input

Comparator B Output

Comparator C Output

Comparator C Inverting Input

Comparator C Noninverting Input

Comparator D Noninverting Input

Comparator D Inverting Input

Comparator D Output

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.

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