WM8786

Pre-Production

w

PP Rev 3.0 December 2005

18

AUDIO INTERFACE CONTROL

AUDIO INTERFACE CONTROL

The audio interface is controlled using the AUDIOF0 and AUDIOF1 pins. Dynamically changing the

audio format may cause erroneous operation of the interfaces and is therefore not recommended.

All ADC data is signed 2’s complement. The length of the digital audio data is always 24 bits.

AUDIOF1 PIN STATUS

AUDIOF0 PIN STATUS

AUDIO INTERFACE

FORMAT

Low

Low

24-bit right justified

Low

High

24-bit left justified

High

Low

24-bit I

High

High

24-bit DSP

Table 3 Audio Interface Format Selection

OVERSAMPLING RATIOS AND SIGMA-DELTA MODULATOR FREQUENCY

For correct operation of the device and optimal performance, the user must select the appropriate

ADC modulator oversampling ratio. The oversampling ratio is selected using the OSR0 and OSR1

pins.

OSR1 PIN STATUS

OSR0 PIN STATUS

OVERSAMPLING RATIO

CONTROL

Low

Low

Single Rate (128fs)

Low

High

Dual Rate (64fs)

High

Low

Quad Rate (32fs)

High

High

Not Valid

Table 4 Oversampling Ratio Selection

The WM8786 can operate at sample rates from 8kHz to 192kHz. The WM8786 uses a sigma-delta

modulator that operates at frequencies between 1.024MHz and 6.144MHz

SAMPLING RATE

(LRCLK)

OVERSAMPLING RATIO

SIGMA-DELTA

MODULATOR

FREQUENCY (MHZ)

8kHz

Single Rate (128fs)

1.024

32kHz

Single Rate (128fs)

4.096

44.1kHz

Single Rate (128fs)

5.6448

48kHz

Single Rate (128fs)

6.144

96kHz

Dual Rate (64fs)

6.144

192kHz

Quad Rate (32fs)

6.144

Table 5 Sigma-delta Modulator Frequency