Data Sheet

XE3005/XE3006

7

D0212-116

2.1.4

Digital Loop Back

In digital loop back mode, the ADC output is routed directly to the DAC input. This allows in-circuit system level

tests. The digital loop back mode can be selected through register J.

2.1.5

Operating Frequency

A master clock (MCLK) has to be applied to the XE3005/3006. The clock frequency of the signal applied to the

MCLK pin may vary between 1.024 MHz minimum and 33.9 MHz maximum. The maximum internal clock signal

frequency (MCLK/div_factor) should not exceed 12.288 MHz.

The div_factor can be set by the user in register I to 1,2 or 4. The default value for div_factor is ‘1’.

2.1.6

Serial Audio Interface

The Serial Audio Interface is a 4-wire interface for bi-directional communication of audio data. It operates on the

bit serial clock BCLK and the frame synchronization signal FSYNC. The sampling frequency of the CODEC

corresponds to the rate at which the Audio Serial Interface will put out succeeding frames. One frame always

corresponds to one sample. One frame always contains 2 channels.

Synchronizing the Serial Audio Interface to the MCLK is recommended. FSYNC and MCLK must have a fixed

ratio as defined by the following relation:

FSYNC = Sampling frequency = frame rate = MCLK/(256 x div_factor).

The pin BCLK defines the time when the data must be presented to the serial audio interface and shifted into (pin

SDI) or out of (pin SDO) the CODEC. The number of BCLK periods in one FSYNC period is 32. The user can

select to use the first 16 clock cycles (channel 1) or the second 16 clock cycles (channel 2) of BLCK to shift in or

out the data samples.

The table below shows some examples of the relationships between MCLK, BCLK and FSYNC

MCLK

Div_factor

BCLK

FSYNC

2048 kHz

1

256 kHz

8 kHz

8192 kHz

4

256 kHz

8 kHz

5120 kHz

1

640 kHz

20 kHz

22579.2 kHz

2

1411.2 kHz

44.1 kHz

The table below shows the possible functional configurations of the serial audio interface

CODEC

supported protocol

master

LFS (long frame sync)

slave

LFS (long frame sync), SFS (short frame sync)

By default the Serial Audio Interface operates in slave, SFS mode. In slave mode the user needs to generate the

signals BLCK, FSYNC and supply to the CODEC.

In master mode the CODEC generates the BLCK and FSYNC signals. In that case the BLCK operates at 32

times the frequency of FSYNC. The CODEC master mode can be used with the LFS protocol only.

The register J is used for the different setups of the serial audio interface.