WM8978GEFLSLASHV datasheet(21/119 Pages) WOLFSON

21 / 119 page

Pre-Production

WM8978

PP Rev 3.0 May 2006

RECOMMENDED POWER UP/DOWN SEQUENCE

In order to minimise output pop and click noise, it is recommended that the WM8978 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.

Mute all analogue outputs.

Set L/RMIXEN = 1 and DACENL/R = 1 in register R3.

Set BUFIOEN = 1 and VMIDSEL[1:0] to required value in register R1. Wait for the VMID supply

to settle. *Refer notes 1 and 2.

Set BIASEN = 1 in register R1.

Set L/ROUT1EN = 1 in register R2.

Enable other mixers as required.

Enable other outputs as required.

Set remaining registers.

Power-up when using the output 1.5x boost stage:

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

Mute all analogue outputs.

Enable unused output chosen from L/ROUT2, OUT3 or OUT4. If unused output not available,

chose one of these outputs not required at power up.

Set BUFDCOPEN = 1 and BUFIOEN = 1 in register R1.

Set SPKBOOST = 1 in register R49.

Set VMIDSEL[1:0] to required value in register R1. Wait for the VMID supply to settle. *Refer

notes 1 and 2.

Set L/RMIXEN = 1 and DACENL/R = 1 in register R3.

Set BIASEN = 1 in register R1.

Set L/ROUT2EN = 1 in register R3. *Note 3.

10. Enable other mixers as required.

11. Enable other outputs as required.

12. Set remaining registers.

Power Down (all cases):

Mute all analogue outputs.

Disable Power Management Register 1. R1 = 0x00.

Disable Power Management Register 2. R2 = 0x00.

Disable Power Management Register 3. R3 = 0x00.

Remove external power supplies.

WM8978GEFL/V датащи(PDF) 21 Page - Wolfson Microelectronics plc