Datasheet

LM555
www.ti.com SNAS548B –MAY 2004–REVISED JULY 2006
Figure 7. Free Running Frequency
FREQUENCY DIVIDER
The monostable circuit of Figure 2 can be used as a frequency divider by adjusting the length of the timing cycle.
Figure 8 shows the waveforms generated in a divide by three circuit.
V
CC
= 5V Top Trace: Input 4V/Div.
TIME = 20μs/DIV. Middle Trace: Output 2V/Div.
R
A
= 9.1kΩ Bottom Trace: Capacitor 2V/Div.
C = 0.01μF
Figure 8. Frequency Divider
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 9 shows the circuit, and in Figure 10 are some
waveform examples.
Figure 9. Pulse Width Modulator
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