Datasheet

Section 8 8-Bit PWM Timer (PWMU)
Rev. 3.00 Sep. 28, 2009 Page 216 of 910
REJ09B0350-0300
(1) Example of Setting
012345 6789101112131415
: Position of additional pulse
1 conversion period
A duty cycle of 0/256 to 255/256 is output as a low-ripple waveform by combining basic pulses and additional pulses.
Duty cycle
Basic
waveform
Additional
pulses
127/256
128/256
129/256
130/256
PWMREG
setting
example
H'7F
H'80
H'81
H'82
112 pulses
128 pulses
128 pulses
128 pulses
15 pulses
0 pulse
1 pulse
2 pulses
Figure 8.9 Example of WMU Setting
(2) Example of Circuit for Use as D/A Converter
The following shows an example of a circuit in which PWMU output pulses are used as a D/A
converter. When a low-pass filter is connected externally to the LSI, low-ripple analog output can
be generated. If pulse division mode is used, a D/A output with even less ripple is available.
This LSI
Low-pass filter Reference values
Resistor: 120 kΩ
Capacitor: 0.1 μF
Figure 8.10 Example of Circuit for Use as a D/A Converter