wm9081 Wolfson Microelectronics plc, wm9081 Datasheet - Page 29

• Manufacturer Part Number: wm9081
• Description: Mono Dac With 2.6w Class Ab/d Speaker Driver, Dynamic Range Controller And Retune Mobile Parametric Equalizer
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
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Table 8 Write Sequencer Control
DEFAULT SEQUENCES
When the WM9081 is powered up, a number of default Control Write Sequences are available in
non-volatile memory. The pre-programmed default settings include Start-Up and Shut-Down
sequences for each of the output drivers. Note that the internal clock, CLK_SYS, must be enabled in
order to run these sequences.
The following default control sequences are provided:
1. Class D Speaker Enable Sequence
Class D Speaker Enable - This sequence powers up the speaker driver in Class D mode, and
enables the DAC signal path. The soft-start VMID circuit is selected as part of this sequence. On
completion, the Lineout is clamped to VMID.
The Class D Speaker Enable sequence is initiated by writing 8100h to Register 38 (26h). This single
operation starts the Control Write Sequencer at Index Address 0 (00h). For typical clocking
configurations, this sequence takes approximately 42ms to run.
Note that this sequence is optimized for pop suppression on the Speaker output. For pop
suppression on the Line Output, please refer to sequence 3.
2. Class D Speaker Disable Sequence
Class D Speaker Disable - This sequence powers down the Class D speaker driver. As part of this
sequence, the DAC is muted and disabled, the Lineout is discharged to AGND and the
reference/bias circuits are disabled. This sequence is applicable to the Class D speaker mode.
R39 (27h)
Write
Sequencer 1
10:4
6:0
9
8
0
WSEQ_ABORT
WSEQ_START
WSEQ_START_
INDEX [6:0]
WSEQ_CURRE
NT_INDEX [6:0]
(read only)
WSEQ_BUSY
(read only)
000_0000
000_0000
0
0
0
Writing a 1 to this bit aborts the
current sequence and returns control
of the device back to the serial
control interface.
Writing a 1 to this bit starts the write
sequencer at the memory location
indicated by the
WSEQ_START_INDEX field. The
sequence continues until it reaches
an “End of sequence” flag. At the
end of the sequence, this bit will be
reset by the Write Sequencer.
Sequence Start Index. This is the
memory location of the first
command in the selected sequence.
Sequence Current Index. This is the
location of the most recently
accessed command in the write
sequencer memory.
Sequencer Busy flag (Read Only).
0 = Sequencer idle
1 = Sequencer busy
Note: it is not possible to write to
control registers via the control
interface while the Sequencer is
Busy.
PP, Rev 3.0, April 2009
WM9081
29