Monday, 13 February 2012

PWM Generator Circuit by Digital register method

PWM Generator Circuit by Digital register method
an example circuit using the digital comparison method
when a microcontroller is available to set the 4-bit digital register
value. A write strobe is required from the micro to latch the 4 data
bits into the register. The 74HC161 counter is free-running,
the frequency being set by the 74HC14 oscillator section, where
it is roughly f = 1/(6.3RC). The resulting frequency of the PWM
signal will be 16 times less than this counter clock frequency,
since it requires 16 pulses to complete one "revolution" of the
counter. With R=2k and C=1nF this results in a counter
frequency of approximately 80kHz which will result in a PWM signal
frequency of 5kHz.

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