XE3005 데이터 시트보기 (PDF) - Semtech Corporation

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XE3005

Low-Power Audio CODEC

Semtech Corporation 

XE3005/XE3006

2 FUNCTIONAL DESCRIPTION

A CODEC is typically used for voice and audio applications as an interface between a Digital Signal processor (DSP) or

microcontroller and the analogue interfaces like a microphone and loudspeaker.

ADC

DAC

MIC-Amplifier

CODEC

Serial Audio Interface

Power Amplifier

SPI

DSP / Microcontroller

„ Digital wireless transmission – Bluetooth™

„ Voice recognition / speech synthesis

Figure 3: Typical usage of CODEC

This chapter provides a brief description of the CODEC features relating to the CODEC configuration. The configuration

of the CODEC is defined by programming registers through a serial interface. A detailed description of the registers

defining details of the CODEC setup can be found in chapter 3 and 7. Digital voice and audio samples are passed

through the Serial Audio Interface.

2.1 DEVICE FUNCTIONS

2.1.1 ADC Signal Channel

The ADC channel is a chain of programmable amplifier, band-pass filter, sigma-delta modulator and a decimation filter.

The amplifier gain is programmable to 5x (default) and 20x. The band-pass filter has cut-off frequencies proportional to

the sampling rate. The sigma-delta modulator operates at a frequency of 64 times the sampling rate. The analog

modulator is followed by a digital decimation filter. The digital output data (16 bits, 2’s complement format) is made

available through the Serial Audio Interface. The format of the Serial Audio interface can be selected through register J.

With the default register settings the ADC can run at a sampling frequency up to 20 kHz. When used with a sampling

frequency higher than 20 kHz, then register C has to be changed.

The whole ADC chain can be powered-down through register I.

© Semtech 2005

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