Page 17 - Template EBook Kita (A4 Document)

TOPIC 1: INTRODUCTION TO 555 TIMER

PIN ASSIGNMENTS

pin 6

THRESHOLD • This is the non-inverting input terminal of
comparator 1, which compares the voltage

applied to the terminal with a reference

voltage of 2/3 Vcc.
•The amplitude of voltage applied to this

terminal is responsible for the set state of flip-

flop.

•When > 2/3 Vcc ('active high') this makes the
output low (0V)* only if pin 2 is HIGH.

Pin 7 is not an input.

It is called discharge terminal because when pin 7
transistor Q1 ON, capacitor discharges

through the transistor Q1. DISCHARGE

When the transistor Q1 is OFF, the capacitor
charges at a rate determined by the external

resistor and capacitor.

pin 8 • A supply voltage of + 5 V
to + 18 V is applied to this

terminal with respect to
SUPPLY
ground .

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