WM8351 datasheet(62/330 Pages) WOLFSON

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WM8351

Production Data

PD, April 2012, Rev 4.5

13.3 ENABLING THE AUDIO CODEC

Before the audio CODEC can be used, it must be enabled by writing to the CODEC_ENA,

SYSCLK_ENA and BIAS_ENA register bits.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R12 (0Ch)

Power

Mgmt 5

CODEC_ENA

Master codec enable bit. Until this bit is set, all

codec registers are held in reset.

0 = All codec registers held in reset

1 = Codec registers operate normally.

R11 (0Bh)

Power

Mgmt 4

SYSCLK_ENA

CODEC SYSCLK enable

0 = disabled

1 = enabled

R8 (08h)

Power

Mgmt 1

BIAS_ENA

Enables bias to analogue audio CODEC

circuitry

0 = disabled

1 = enabled

Table 19 Enabling the Audio CODEC

Each individual part of the audio CODEC (e.g. left/right ADC, left/right DAC, each analogue output

pin, mic bias etc.) also has its own enable bit, which must be set before that part of the CODEC can

be used. These enable bits are described in the sections that follow.

In order to minimize output pop and click noise, it is recommended that the WM8351 device is

powered up and down under control using the following sequences:

Power Up:

Ensure the CODEC power supplies are available before the CODEC is enabled

R12[CODEC_ENA]=1 . The order in which this is done should be DCVDD, DBVDD then

HPAVVD And/Or AVDD

Mute all outputs

Enable the anti-pop circuits by setting ANTI_POP. There are three Anti-pop setting options.

Recommended value is ANTI_POP = 01.

Ensure external capacitors are full discharged on all outputs that are used by delaying 250ms

Set the mixers and DAC volume to required settings

Enable VMID by setting VMID_ENA = 1. VMID should raise in a controlled fashion and charge

the output capacitors

Wait approx 500ms to allow VMID to charge.

Disable the anti-pop circuits by setting ANTI_POP = 00.

Un-mute all outputs

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