LMC555 Datasheet, PDF (9/21 Pages) National Semiconductor (TI) – CMOS Timer

LMC555
www.ti.com
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
TIME = 20 µs/Div.
R_A = 9.1 kΩ
C = 0.01 µF
Top Trace: Input 4 V/Div.
Middle Trace: Output 2 V/Div.
Bottom Trace: Capacitor 2 V/Div.
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
TIME = 0.2 ms/Div.
R_A = 9.1 kΩ
C = 0.01 µF
Top Trace: Modulation 1 V/Div.
Bottom Trace: Output Voltage 2 V/Div.
Figure 13. Pulse Width Modulator Waveforms
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