WM8778SEDSSLASHR datasheet(19/50 Pages) WOLFSON

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Production Data

WM8778

PD Rev 4.0 April 2005

In left justified, right justified and I

2S modes; the minimum number of BCLKs per DACLRC/ADCLRC

period is 2 times the selected word length. ADCLRC/DACLRC must be high for a minimum of word

length BCLKs and low for a minimum of word length BCLKs. Any mark to space ratio on

ADCLRC/DACLRC is acceptable provided the above requirements are met.

In DSP mode A or B, DACLRC is used as a frame sync signal to identify the MSB of the first word.

The minimum number of DACBCLKs per DACLRC period is 2 times the selected word length. Any

mark to space ratio is acceptable on DACLRC provided the rising edge is correctly positioned. The

ADC data may also be output in DSP mode A or B, with ADCLRC used as a frame sync to identify

the MSB of the first word. The minimum number of ADCBCLKs per ADCLRC period is 2 times the

selected word length.

LEFT JUSTIFIED MODE

In left justified mode, the MSB of DIN is sampled by the WM8778 on the first rising edge of

DACBCLK following a DACLRC transition. The MSB of the ADC data is output on DOUT and

changes on the same falling edge of ADCBCLK as ADCLRC and may be sampled on the rising edge

of ADCBCLK. ADCLRC and DACLRC are high during the left samples and low during the right

samples (Figure 13).

LEFT CHANNEL

RIGHT CHANNEL

DACLRC/

ADCLRC

DACBCLK/

ADCBCLK

DIN/

DOUT

1/fs

n-2 n-1

LSB

MSB

n-2 n-1

LSB

MSB

Figure 13 Left Justified Mode Timing Diagram

RIGHT JUSTIFIED MODE

In right justified mode, the LSB of DIN is sampled by the WM8778 on the rising edge of DACBCLK

preceding a DACLRC transition. The LSB of the ADC data is output on DOUT and changes on the

falling edge of ADCBCLK preceding a ADCLRC transition and may be sampled on the rising edge of

ADCBCLK. ADCLRC and DACLRC are high during the left samples and low during the right samples

(Figure 14).

LEFT CHANNEL

RIGHT CHANNEL

DACLRC/

ADCLRC

DACBCLK/

ADCBCLK

DIN/

DOUT

1/fs

n-2 n-1

LSB

MSB

n-2 n-1

LSB

MSB

Figure 14 Right Justified Mode Timing Diagram

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