WM8993 datasheet(144/229 Pages) WOLFSON

144 / 229 page

WM8993

Production Data

PD, November 2010, Rev 4.0

144

The following default control sequences are provided:

Headphone Cold Start-Up - This sequence powers up the headphone driver and charge pump.

It commands the DC Servo to perform offset correction. It enables the master bias required for

analogue functions. This sequence is intended for enabling the headphone output after initial

power-on, when DC offset correction has not previously been run.

Headphone Warm Start-Up - This sequence is similar to the Headphone Cold Start-Up, but

does not include the DC Servo operation. This sequence is intended for fast enabling of the

headphone output when DC offset correction has previously been scheduled and provided the

analogue gain settings have not been updated since scheduling the DC offset correction.

Speaker Start-Up - This sequence powers up the stereo speaker driver. It also enables the

master bias required for analogue functions.

Earpiece Start-Up - This sequence powers up the earpiece driver. It also enables the master

bias required for analogue functions. The soft-start VMID option is used in order to suppress

pops when the driver is enabled. This sequence is intended for enabling the earpiece driver

when the master bias has not previously been enabled.

Line Output Start-Up - This sequence powers up the line outputs. Active discharge of the line

outputs is selected, followed by the soft-start VMID enable, followed by selection of the master

bias and un-muting of the line outputs. This sequence is intended for enabling the line drivers

when the master bias has not previously been enabled.

Speaker and Headphone Fast Shut-Down - This sequence implements a fast shutdown of the

speaker and headphone drivers. It also disables the DC Servo and charge pump circuits, and

disables the analogue bias circuits using the soft-start (ramp) feature. This sequence is

intended as a shut-down sequence when only the speaker or headphone drivers are enabled.

Generic Shut-Down - This sequence shuts down all of the WM8993 output drivers, DC Servo,

charge pump and analogue bias circuits. It is similar to the Fast Shut-Down sequence, with the

additional control of the earpiece and line output drivers. Active discharge of the line outputs is

included and all drivers are disabled as part of this sequence.

Specific details of each of these sequences is provided below.

WM8993 Datasheet(PDF) 144 Page - Wolfson Microelectronics plc