WM8728
Production Data
DE-EMPHASIS MODE
Setting the DEEMPH register bit puts the digital filters into de-emphasis mode:
REGISTER ADDRESS
0010
BIT
LABEL
DEFAULT
DESCRIPTION
1
DEEMPH
0
De-emphasis mode select:
0 : De-emphasis Off
DAC Control
1: De-emphasis On
Table 12 De-emphasis Control
POWERDOWN MODE
Setting the PWDN register bit immediately connects all outputs to VMID and selects a low power
mode. All trace of the previous input samples is removed, and all control register settings are
cleared. When PWDN is cleared again the first 16 input samples will be ignored, as the FIR will
repeat it's power-on initialisation sequence.
REGISTER ADDRESS
0010
BIT
LABEL
DEFAULT
DESCRIPTION
Power Down Mode Select:
0 : Normal Mode
2
PWDN
0
DAC Control
1: Power Down Mode
Table 13 Powerdown control
DIGITAL AUDIO INTERFACE CONTROL REGISTERS
The WM8728 has a fully featured digital audio interface that is a superset of that contained in the
WM8716. Interface format is selected via the IWL[2:0] register bits in register M2 and the I2S
register bit in M3.
REGISTER ADDRESS
0010
BIT
LABEL
DEFAULT
DESCRIPTION
5:3
IWL[2:0]
000000
Interface format Select
DAC Control
0011
0
I2S
0
Interface format Select
Interface Control
Table 14 Interface Format Controls
IW2
I2S
IW1
IW0
AUDIO INTERFACE DESCRIPTION
(NOTE 1)
0
0
0
0
0
0
0
0
1
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
1
0
1
0
16 bit right justified mode
20 bit right justified mode
24 bit right justified mode
24 bit left justified mode
16 bit I2S mode
24 bit I2S mode
20 bit I2S mode
20 bit left justified mode
16 bit DSP mode
20 bit DSP mode
24 bit DSP mode
32 bit DSP mode
16 bit left justified mode
Table 15 Audio Data Input Format
Note:
In all modes, the data is signed 2's complement. The digital filters always input 24-bit data. If the
DAC is programmed to receive 16 or 20 bit data, the WM8728 pads the unused LSBs with
ZEROS. If the DAC is programmed into 32-bit mode, the 8 LSBs are treated as zero.
PD Rev 4.2 April 2004
21
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
