SNC20AS

Direct Drive Speech Controller

Ver: 0.3

Sept 20, 2007

6

5.8. DAC & PWM

SNC20AS is an advanced chip to be designed having two optimal methods to play out

the voices. One is DAC and the other is PWM. Upon user’s applications, user can

select either DAC or PWM in his design. Please be aware that only one method can

be activated at a time.

DAC: A 7-bit current type digital-to-analog converter is built-in SNC20AS. The

relationship between input digital data and output analog current signal is listed in

the following table. Also, the recommended application circuit is illustrated as

follows.

Input data

Typical value of output current (mA)

0

0

1

3/127

…

N

n*(3/127)

…

127

3

DAC output

VCC

BUO1/VO

1K