WM8972LEFLSLASHR datasheet(46/49 Pages) WOLFSON

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WM8972L

Preliminary Technical Data

PTD Rev 2.2 June 2004

MINIMISING POP NOISE AT THE ANALOGUE OUTPUTS

To minimise any pop or click noise when the system is powered up or down, the following procedures

are recommended.

POWER UP

•

Switch on power supplies. By default the WM8972L is in Standby Mode, the DAC is

digitally muted and the Audio Interface, Line outputs and Headphone outputs are all OFF

(DACMU = 1 Power Management registers 1 and 2 are all zeros).

•

Enable Vmid and VREF, then wait for time TBD

•

Enable DAC as required

•

Enable line and / or headphone output buffers as required.

•

Set DACMU = 0 to soft-un-mute the audio DAC.

POWER DOWN

•

Set DACMU = 1 to soft-mute the audio DAC.

•

Disable all output buffers, then wait for time TBD.

•

Switch off the power supplies.

POWER MANAGEMENT EXAMPLES

OPERATION MODE

POWER

MANAGEMENT (1)

POWER

MANAGEMENT (2)

ADC

DAC Output Buffers

O2+

O2-

Line-in Record

Mono Microphone Record

Microphone to mono out

Speaker Phone Call [OUTINV = 1]

Record Phone Call [L channel = mic with

boost, R channel = RX, enable mono mix]

Table 37 Register Settings for Power Management

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