WM8912 Datasheet, PDF (92/129 Pages) Wolfson Microelectronics plc – Ultra Low Power DAC with Headphone Driver for Portable Audio Applications

WM8912
REGISTER
ADDRESS
R108 (6Ch)
Write Sequencer 0
R111 (6Fh)
Write Sequencer 3
R33 (21h)
DAC Digital 1
VALUE
0100h
0100h
0000h
Table 62 Quick Start-up Control
DESCRIPTION
WSEQ_ENA = 1
WSEQ_WRITE_INDEX = 0_0000
WSEQ_ABORT = 0
WSEQ_START = 1
WSEQ_START_INDEX = 0_0000
DAC_MONO = 0
DAC_SB_FILT = 0
DAC_MUTERATE = 0
DAC_UNMUTE_RAMP = 0
DAC_OSR128 = 0
DAC_MUTE = 0
DEEMPH = 00
Production Data
The WSEQ_BUSY bit (in Register R112, see Table 56) will be set to 1 while the sequence runs.
When this bit returns to 0, the device has been set up and is ready for DAC playback operation.
FAST START-UP FROM STANDBY
The default start-up sequence runs the DC Servo to remove DC offsets from the outputs. The offset
for this path selection is then stored in memory. Provided that power is maintained to the chip, and a
software reset is not performed, then the DC offset correction will be held in memory on the WM8912.
This allows the DC Servo calibrations to be omitted from the start-up sequence if the offset correction
has already been performed. By omitting this part of the start-up sequence, a fast start-up time of less
than 50ms can be achieved.
The register write sequence described in Table 63 replaces the default DC Servo operation with
dummy operations, allowing a fast start-up to be achieved, assuming the device is initially in a
standby condition with DC offset correction previously performed.
Note that, if power is removed from the WM8912 or if a software reset is performed, then the default
sequence will be restored, and the DC offset correction will be necessary on the output paths once
more.
REGISTER
ADDRESS
R108 (6Ch)
Write Sequencer 0
R109 (6Dh)
Write Sequencer 1
R110 (6Eh)
Write Sequencer 2
R111 (6Fh)
Write Sequencer 3
R33 (21h)
DAC Digital 1
VALUE
0111h
00FFh
0000h
0100h
0000h
DESCRIPTION
WSEQ_ENA = 1
WSEQ_WRITE_INDEX = 1_0001
WSEQ_DATA_WIDTH = 000
WSEQ_DATA_START = 0000
WSEQ_ADDR = 1111_1111
WSEQ_EOS = 0
WSEQ_DELAY = 0000
WSEQ_DATA = 0000_0000
WSEQ_ABORT = 0
WSEQ_START = 1
WSEQ_START_INDEX = 00_0000
DAC_MONO = 0
DAC_SB_FILT = 0
DAC_MUTERATE = 0
DAC_UNMUTE_RAMP = 0
DAC_OSR128 = 0
DAC_MUTE = 0
DEEMPH = 00
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PD, Rev 4.1, February 2013
92