NE555/SA555/NA555

Document number: DS35112 Rev. 5 - 2

2 of 14

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February 2021

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NE555

Pin Descriptions

Pin Name

Pin Number

Description

GND

1

Ground

TRIG

2

OUT

3

Timer output

RESET

4

Reset active low

CONT

5

External adjustment of internal threshold and trigger voltages

THRES

6

DISCH

7

Low impedance discharge path

8

Chip supply voltage

Functional Block Diagram

RESET can override TRIG, which can override THRESH

Functional Table

RESET

Nominal Trigger

Voltage

Threshold

Voltage

Output

Discharge

Switch

Low

Irrelevant

Irrelevant

Low

On

High

Irrelevant

High

Off

High

Low

On

High

As previously established

RESET

THRES

TRIG

GND

DISCH

OUT

1

2

3

4

5

6

7

8

R1

R2

S

O