R8A66173SP

REJ03F0264-0100 Rev.1.00 Jan.24.2008

Page 2 of 12

BLOCK DIAGRAM (EACH CHANNEL)

FUNCTION

The PWM output waveform of each channel is controlled by taking in PWM data from MCU or other device via

12-bit PWM data is input being divided between upper 8-bits (upper byte) and lower 4-bits.

The lower 4-bit data is combined with command data such as channel designation and input as 8-bit data

(lower byte).

The lower byte should be written first, and then the upper byte. Even if only the upper byte is to be changed,

rewrite from the lower byte.

The PWM waveform changes according to the new setting from the next cycle.

One cycle of PWM waveform (=4096 divisions; 12-bit resolution) are divided into 16 (2

subsection consists of 256 (=2

One subsection t consists of an 8-bit PWM waveform (basic waveform). The “H” width of this waveform is

determined according to the upper 8-bits of PWM data. One cycle has 16 subsections t, each of which has

this basic waveform. Among them, those which are designated by the 4-bit-rate multiplier are conditioned to have

a “H” width that is longer by

τ. The lower 4-bits of PWM data are used to specify those subsections (tm). The

waveform of other subsections remains unchanged.

The PWM waveform (12-bit resolution) is a combination of two types of waveforms which are different in “H”

width, as described above.

When output control input OC is “H”, the output of every 4-channel turns high-impedance from the next cycle.

When reset input R is “L”, the output of every channel turns high-impedance as soon as the ongoing cycle is

completed, and PWM data of all channels is reset. If R input is changed from “L” to “H”, the next cycle starts,

however, the output of the channels remains high-impedance.

To enable output, rewrite input data for each channel.

Input

register

Vcc

PWM1

PWM3

WR

3

CS

1

2

6

13

12

14

11

4

5

Control

circuit

OC

R

Upper byte

register

Low er byte

register

PWM

register

8-bit

PWM circuit

4-bit-rate

multiplier

12-bit

PWM circuit

Oscillation

circuit

1/2

divider

To other channels

PWM2

PWM4

GND

8

10

7

9