KA555

6

operation, the trigger terminal and the threshold terminal are connected so that a self-trigger is formed, operating as a multi

resetting the F/F and causing the timer output to become low. This in turn turns on the discharging Tr. and the C1 discharges

output on the trigger terminal becomes high and the timer output becomes high again. The discharging Tr. turns off and the

is high, the equivalent circuit for charging capacitor C1 is as follows

:

Figure 7. Waveforms of Astable Operation

Vcc

R

A

R

B

C1

Vc1(0-)=Vcc/3

C

1

dv

c1

dt

−−−−−−−−

V

cc

V0-

()

–

R

A

R

B

+

−−−−−−−−−−−−−−−−−−−

=

1

()

V

C1

0+

()

V

CC

3

⁄

=

2

()

V

C1

t

()

V

CC

1

2

3

−−e

-

t

R

A

R

B

+

()C1

−−−−−−−−−−−−−−−−−−−−−−

–







–











=

3

()