Rev. 1.0, 02/00, page 367 of 1141
18.3
8-Bit PWM Operation
The 8-bit PWM outputs PWM pulses having a cycle length of 256 states and a pulse width
determined by the data registers (PWR).
The output PWM pulse can be converted to a DC voltage through integration in a low-pass filter.
Figure 18.2 shows the output waveform example of 8-bit PWM. The pulse width (Twidth) can be
obtained by the following expression:
Twidth = (1/
φ
)
×
(PWR setting value)
T width
Pulse width
T width
Pulse cycle
(256 states)
T width
Pulse width
T width
Pulse cycle
(256 states)
H'00
PWRn setting
value
H'FF
FRC lower
8-bit value
PWRn pin
output
(Positive
polarity)
(n=3 to 0)
(Negative
polarity)
Figure 18.2 8-bit PWM Output Waveform (Example)