NE555/SA555/NA555

PRECISION TIMERS

NE555/SA555/NA555

Document number: DS35112 Rev. 4 - 2

1 of 14

www.diodes.com

February 2012

© Diodes Incorporated

Description

These devices are precision timing circuits capable of

producing accurate time delays or oscillation. In the time-

delay or monostable mode of operation, the timed interval is

controlled by a single external resistor and capacitor network.

In the astable mode of operation, the frequency and duty

cycle can be controlled independently with two external

resistors and a single external capacitor.

The threshold and trigger levels normally are two-thirds and

by use of the control-voltage terminal. When the trigger input

falls below the trigger level, the flip-flop is set, and the output

goes high. If the trigger input is above the trigger level and

the threshold input is above the threshold level, the flip-flop is

reset and the output is low. The reset (RESET) input can

override all other inputs and can be used to initiate a new

timing cycle. When RESET goes low, the flip-flop is reset,

and the output goes low. When the output is low, a low-

impedance path is provided between discharge (DISCH) and

ground.

The output circuit is capable of sinking or sourcing current up

to 200mA. Operation is specified for supplies of 5V to 15V.

With a 5-V supply, output levels are compatible with TTL

inputs.

Features

•

Timing from microseconds to hours

•

Astable or monostable operation

•

Adjustable duty cycle

•

TTL compatible output can source or sink up to 200mA

•

“Green” Molding Compound (No Br, Sb)

•

Lead Free Finish/ RoHS Compliant (Note 1)

Pin Assignments

Notes:

1. EU Directive 2002/95/EC (RoHS). All applicable RoHS exemptions applied. Please visit our website at

http://www.diodes.com/products/lead_free.html.

(Top View)

SO-8

V

CC

DISCH

THRES

CONT

OUT

TRIG

GND

RESET