11/30

STA304A

6.0 DAP INPUT STAGE

The device provides 3 mutually exclusive input interfaces: I2S, S/PDIF and AC`97. Hereby is a small description

of the characteristics for each of them and a table showing how to select it.

Figure 6.

Using this input interface a maximum of 4 channels can be sent to the DSP. As detailed in the related paragraph

this I/F can be configured both as master or slave. When in master the sampling frequency is fixed to 48 KHz

and the SRC can be bypassed using the

selected the full range between 32KHz and 96KHz is supported but the SRC must always be in the processing

path (no bypass). In order to select this interface the AC97_MODE pin must be tied to GND and the

I2S_SPDIF_Sel bit must be 0.

6.2 Input from S/PDIF

This interface is compliant with the AES/EBU IEC 958, S/PDIF and EIAJ CP-340/1201 professional and con-

sumer standards. The full range from 32 KHz up to 96 KHz is supported but the SRC bypass option must be

switched off. Using the

mode is selected the line receiver can decode differential as well as single ended inputs. The receiver consists

of a differential input

corrupting the data recovered. The minimum input differential voltage is 200 mV.

If the digital mode is selected only the single ended operation is supported; the input signal should be CMOS

compliant.

In order to select this interface the AC97_MODE pin must be tied to GND and the I2S_SPDIF_Sel must be 1.

6.3 Input from AC`97

In order to select this interface the AC97_MODE pin must be tied to VDD (I2S_SPDIF_Sel bit ‘is don’t care).

The AC`97 interface can be configured either as primary or secondary device using the external configuration

pin SA.

This interface support 4 sampling frequencies, according to the

Variable and Double Rate Audio Codec `97

YRAM

SRC

AC97

I2S

S/PDIF

LEFT

RIGHT

SL/CENTER

SR

CENTER

LFE

AC97_Sel

I2S_SPDIF_Sel

SRC_Bypass

PLL

MCK

PLL_Factor

PLL_Bypass

XTI

DSP

DDX

I2S

I2C

YRAM

LEFT

RIGHT

SL/CENTER

SR

CENTER

LFE

/1024

/2 or /8

LRCK

CK_OUT

LRCK