SNC558

Two Channel Direct Drive Speech Controller

PAD

weak

Port Data

Port Status

Output Port Configuration (P40~P43, P50~P53)

Note: All weak N-MOS’s can serve as pull-low resistors.

5.7. IR Function

P33 can be modulated with 38.5KHz square wave before sent out to P33 pin. The IR

signal can be achieved by this modulated signal.

Mode

38.5KHZ

P33

PAD

"1"

5.8. DAC & PWM

SNC558 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 SNC558. 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.

Ver: 1.2

November 26, 2002

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