LM122 National Semiconductor, LM122 Datasheet

LM122

Manufacturer Part Number

LM122

Description

Precision Timers

Manufacturer

National Semiconductor

Datasheet

1.LM122.pdf (14 pages)

Available stocks

Company

Part Number

Manufacturer

Quantity

Price

Company:

Meier Automation Equipment Co., Limited

Part Number:

LM122H

Manufacturer:

NS/国半

Quantity:

20 000

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C 1995 National Semiconductor Corporation

LM122 LM322 LM3905 Precision Timers

General Description

The LM122 series are precision timers that offer great ver-

satility with high accuracy They operate with unregulated

supplies from 4 5V to 40V while maintaining constant timing

periods from microseconds to hours Internal logic and reg-

ulator circuits complement the basic timing function

enabling the LM122 series to operate in many different ap-

plications with a minimum of external components

The output of the timer is a floating transistor with built in

current limiting It can drive either ground referred or supply

referred loads up to 40V and 50 mA The floating nature of

this output makes it ideal for interfacing lamp or relay driv-

ing and signal conditioning where an open collector or emit-

ter is required A ‘‘logic reverse’’ circuit can be programmed

by the user to make the output transistor either ‘‘on’’ or

‘‘off’’ during the timing period

The trigger input to the LM122 series has a threshold of

1 6V independent of supply voltage but it is fully protected

against inputs as high as

supply The circuitry reacts only to the rising edge of the

trigger signal and is immune to any trigger voltage during

the timing periods

An internal 3 15V regulator is included in the timer to reject

supply voltage changes and to provide the user with a con-

venient reference for applications other than a basic timer

External loads up to 5 mA can be driven by the regulator An

internal 2V divider between the reference and ground sets

the timing period to 1 RC The timing period can be voltage

controlled by driving this divider with an external source

through the V

achieved

Connection Diagrams

See NS Package Number H10C

Order Number LM122H

Metal Can Package

ADJ

Top View

pin Timing ratios of 50 1 can be easily

TL H 7768– 6

TL H 7768

40V even when using a 5V

See NS Package Number N14A

Dual-In-Line Package

Order Number LM322N

Top View

The comparator used in the LM122 utilizes high gain PNP

input transistors to achieve 300 pA typical input bias current

over a common mode range of 0V to 3V A boost terminal

allows the user to increase comparator operating current for

timing periods less than 1 ms This lets the timer operate

over a 3 s to multi-hour timing range with excellent repeat-

ability

The LM122 operates over a temperature range of

0 C to

except that the boost and V

able limiting minimum timing period to 1 ms

Features

125 C An electrically identical LM322 is specified from

Immune to changes in trigger voltage during timing

interval

Timing periods from microseconds to hours

Internal logic reversal

Immune to power supply ripple during the timing

interval

Operates from 4 5V to 40V supplies

Input protected to

Floating transistor output with internal current limiting

Internal regulated reference

Timing period can be voltage controlled

TTL compatible input and output

TL H 7768 – 7

70 C The LM3905 is identical to the LM122 series

40V

See NS Package Number N08E

Order Number LM3905N

Dual-In-Line Package

ADJ

pin options are not avail-

Top View

RRD-B30M115 Printed in U S A

February 1995

TL H 7768 – 8

55 C to

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