XE3005 데이터 시트보기 (PDF) - Semtech Corporation

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XE3005

Low-Power Audio CODEC

Semtech Corporation 

XE3005/XE3006

2.1.9 Sandman™ DAC Function

The Sandman™ function monitors the signals, which are processed in the ADC signal, channel and the DAC signal

channel. The logic output signal SMDA indicates whether the DAC signal channel processes an audio signal or only

noise, and this for certain duration. The reference signal amplitude can be selected through register P, the time window

parameters are the off time and on time (registers L, M and N).

FSYNC

BCLK

SDI

Serial Audio

Interface

Sandman

Interface

Reg I, bit 4

PWM

DAC

Power

amplifier

SMDA

VDDPA

AOUTP

AOUTN

VSSPA

Figure 9: Implementation of the Sandman function for the DAC (SMDA)

The logic output SMDA can be employed to power-down other devices in the application, such as an external audio

power amplifier. By setting bit 4 in register I, the on-chip DAC signal channel can be powered-down through SMDA too.

The Sandman™ function is illustrated in Figure 9 and is valid for both SMAD (related to the ADC signal) and SMDA

(related to the DAC signal).

AIN/SDO

(AOUT/SDI)

+ reference

On-time counter

Off-time counter

- reference

Time step = 1/fs = 1/FSYNC

SMAD

(SMDA)

on-time

off-time

12

3

4 56 7

89

Figure 10: Illustration of the Sandman™ function.

10 time

© Semtech 2005

www.semtech.com

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