LMC555
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SNAS558J –FEBRUARY 2000–REVISED MARCH 2013
FREQUENCY DIVIDER
The monostable circuit of Figure 5 can be used as a frequency divider by adjusting the length of the timing cycle.
Figure 11 shows the waveforms generated in a divide by three circuit.
V
CC
= 5V Top Trace: Input 4 V/Div.
TIME = 20 µs/Div. Middle Trace: Output 2 V/Div.
R
A
= 9.1 kΩ Bottom Trace: Capacitor 2 V/Div.
C = 0.01 µF
Figure 11. Frequency Divider Waveforms
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 the Control Voltage Terminal. Figure 12 shows the circuit,
and in Figure 13 are some waveform examples.
Figure 12. Pulse Width Modulator
V
CC
= 5V Top Trace: Modulation 1 V/Div.
TIME = 0.2 ms/Div. Bottom Trace: Output Voltage 2 V/Div.
R
A
= 9.1 kΩ
C = 0.01 µF
Figure 13. Pulse Width Modulator Waveforms
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