WM9093ECSSLASHR datasheet(52/84 Pages) WOLFSON

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WM9093

Production Data

PD, March 2012, Rev 4.2

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

1:0

DCS_STARTUP_C

OMPLETE [1:0]

DC Servo Start-Up status

0 = Start-Up DC Servo mode not

completed.

1 = Start-Up DC Servo mode

complete.

Bit [1] = HPOUT1R

Bit [0] = HPOUT1L

Table 28 DC Servo Enable and Start-Up Modes

DC SERVO ACTIVE MODES

The DC Servo modes described above are suitable for initialising the DC offset correction circuit on

the Headphone outputs as part of a controlled start-up sequence which is executed before the signal

path is fully enabled. Additional modes are available for use whilst the signal path is active; these

modes may be of benefit following a large change in signal gain, which can lead to a change in DC

offset level. Periodic updates may also be desirable to remove slow drifts in DC offset caused by

changes in parameters such as device temperature.

The DC Servo circuit is enabled on HPOUT1L and HPOUT1R by setting DCS_ENA_CHAN_0 and

DCS_ENA_CHAN_1 respectively, as described earlier in Table 28.

Writing a logic 1 to DCS_TRIG_SINGLE_n initiates a single DC offset measurement and adjustment

to the associated output; (‘n’ = 0 for Left channel, 1 for Right channel). This will adjust the DC offset

correction on the selected channel by no more than 1LSB (0.25mV).

Setting DCS_TIMER_PERIOD_01 to a non-zero value will cause a single DC offset measurement

and adjustment to be scheduled on a periodic basis. Periodic rates ranging from every 0.52s to in

excess of 2hours can be selected.

Writing a logic 1 to DCS_TRIG_SERIES_n initiates a series of DC offset measurements and applies

the necessary correction to the associated output. The number of DC Servo operations performed is

determined by DCS_SERIES_NO_01. A maximum of 128 operations may be selected, though a

much lower value will be sufficient in most applications.

The DC Servo control fields associated with active modes (suitable for use on a signal path that is in

active use) are described in Table 29.

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