NE555 - SA555 - SE555

Application information

13/20

4.3

Pulse width modulator

When the timer is connected in the monostable mode and triggered with a continuous pulse

train, the output pulse width can be modulated by a signal applied to pin 5. Figure 18 shows

the circuit.

Figure 18.

Pulse width modulator

4.4

Linear ramp

source, a linear ramp is generated. Figure 19 shows a circuit configuration that will perform

this function.

Figure 19.

Linear ramp

Trigger

Output

R

C

NE555

2

4

3

1

5

6

7

Modulation

Input

8

A

Trigger

Output

C

NE555

2

4

3

1

5

6

7

8

E

0.01

R2

R1

R

2N4250

or equiv.