the PWMIN signal and the internal signals, the

PWMIN signal rate must be calculated by the ex-

ternal microcontroller using the same frequency

signal provided to the chip through the pin fsys.

Digital Multiplier

This unit contains a multiplier executing the multi-

plication of each sample provided by the memory

by the value stored in kval register.

The output value is a 10-bit word, plus the sign bit.

PWM Converter

The PWM converter receives from the digital mul-

tiplier three 10 bit digital number and converts it

into three PWM signals.

A counter counts up (from 0 to 255) and down

(from 255 to 0) at the Fsys rate in continuos

mode. Three 8-bit input registers are written with

the 8 most significant bit of the word to be con-

verted and compared to the counter value. The

comparator output is:

COMPARATOR

8 MSB

OUTPUT MULTIPLIER

D98IN886

OUTPUT

OUTPUT PWM:

LSB

00

01

10

11

WHERE:

A HALF FSYS PERIOD

A FSYS PERIOD

Figure 11.

COUNTER

OUTPUT COMPARATOR

0

255

D98IN885A

510 Tsys

Figure 10.

L7203

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