WM8731 / WM8731L
Production Data
Once the WM8731/L has acknowledged a correct address, the controller will send eight data bits (bits
B15-B8). WM8731/L will then acknowledge the sent data by pulling SDIN low for one clock pulse.
The controller will then send the remaining eight data bits (bits B7-B0) and the WM8731/L will then
acknowledge again by pulling SDIN low.
A stop condition is defined when there is a low to high transition on SDIN while SCLK is high. If a start
or stop condition is detected out of sequence at any point in the data transfer then the device will
jump to the idle condition.
After receiving a complete address and data sequence the WM8731/L returns to the idle state and
waits for another start condition. Each write to a register requires the complete sequence of start
condition, device address and R/W bit followed by the 16 register address and data bits.
POWER DOWN MODES
The WM8731/L contains power conservation modes in which various circuit blocks may be safely
powered down in order to conserve power. This is software programmable as shown in the table
below.
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
0000110
0
1
LINEINPD
1
Line Input Power Down
1 = Enable Power Down
0 = Disable Power Down
Power Down
Control
MICPD
1
Microphone Input an Bias
Power Down
1 = Enable Power Down
0 = Disable Power Down
ADC Power Down
2
3
4
5
6
7
ADCPD
1
1
1
0
0
1
1 = Enable Power Down
0 = Disable Power Down
DAC Power Down
DACPD
1 = Enable Power Down
0 = Disable Power Down
Line Output Power Down
1 = Enable Power Down
0 = Disable Power Down
Oscillator Power Down
1 = Enable Power Down
0 = Disable Power Down
CLKOUT power down
1 = Enable Power Down
0 = Disable Power Down
Power Off Device
OUTPD
OSCPD
CLKOUTPD
POWEROFF
1 = Device Power Off
0 = Device Power On
Table 26 Power Conservation Modes Software Control
The power down control can be used to either a) permanently disable functions when not required in
certain applications or b) to dynamically power up and down functions depending on the operating
mode, e.g.: during playback or record. Please follow the special instructions below if dynamic
implementations are being used.
LINEINPD: Simultaneously powers down both the Line Inputs. This can be done dynamically without
any audible effects either on the ADC or to the Line Outputs in Bypass mode. This is of use when the
device enters Playback, Pause or Stop modes or the Microphone input has been selected.
PD, Rev 4.9, October 2012
47
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
