WM8510GEDSSLASHV datasheet(48/56 Pages) WOLFSON

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WM8510

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PP Rev 1.2 December 2004

RECOMMENDED POWER UP/DOWN SEQUENCE

In order to minimise output pop and click noise, it is recommended that the WM8510 device is

powered up and down using one of the following sequences:

Power Up When NOT Using the Output 1.5x Boost Stage:

Turn on external power supplies. Wait for supply voltage to settle.

Set BIASEN = 1, BUFIOEN = 1 and also the VMIDSEL[1:0] bits in the Power Management

1 register. * Notes 1 and 2.

Wait for the VMID supply to settle. * Note 2.

Enable DAC by setting DACEN = 1.

Enable mixers as required.

Enable output stages as required.

Unmute DAC by setting DACMU = 0.

Power Up When Using the Output 1.5x Boost Stage:

Turn on external power supplies. Wait for supply voltage to settle.

Enable 1.5x output boost. Set MONOBOOST = 1 and SPKBOOST = 1 as required.

Set BIASEN = 1, BUFIOEN = 1, BUFDCOPEN = 1 and also the VMIDSEL[1:0] bits in the

Power Management 1 register. * Notes 1 and 2.

Wait for the VMID supply to settle. * Note 2.

Enable DAC by setting DACEN = 1.

Enable mixers as required.

Enable output stages as required.

Unmute DAC by setting DACMU = 0.

Power Down (all cases):

Soft mute DAC by setting DACMU = 1.

Disable all output stages.

Turn off external power supplies.

Notes:

This step enables the internal device bias buffer and the VMID buffer for unassigned

inputs/outputs. This will provide a startup reference voltage for all inputs and outputs. This will

cause the inputs and outputs to ramp towards VMID (NOT using output 1.5x boost) or 1.5 x

(AVDD/2) (using output 1.5x boost) in a way that is controlled and predictable (see note 2).

Choose the value of the VMIDSEL bits based on the startup time (VMIDSEL=10 for slowest

startup, VMIDSEL=11 for fastest startup). Startup time is defined by the value of the VMIDSEL

bits (the reference impedance) and the external decoupling capacitor on VMID.

In addition to the power on sequence, it is recommended that the zero cross functions are used when

changing the volume in the PGAs to avoid any audible pops or clicks.

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