LM555

Timer

General Description

The LM555 is a highly stable device for generating accurate

time delays or oscillation. Additional terminals are provided

for triggering or resetting if desired. In the time delay mode of

operation, the time is precisely controlled by one external

resistor and capacitor. For astable operation as an oscillator,

the free running frequency and duty cycle are accurately

controlled with two external resistors and one capacitor. The

circuit may be triggered and reset on falling waveforms, and

the output circuit can source or sink up to 200mA or drive

TTL circuits.

Features

n

Direct replacement for SE555/NE555

n

Timing from microseconds through hours

n

Operates in both astable and monostable modes

n

Adjustable duty cycle

n

Output can source or sink 200 mA

n

Output and supply TTL compatible

n

Temperature stability better than 0.005% per ˚C

n

Normally on and normally off output

n

Available in 8-pin MSOP package

Applications

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Precision timing

n

Pulse generation

n

Sequential timing

n

Time delay generation

n

Pulse width modulation

n

Pulse position modulation

n

Linear ramp generator

Schematic Diagram

00785101

July 2006

© 2006 National Semiconductor Corporation

DS007851

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