WM8976_11 Datasheet, PDF (80/114 Pages) Wolfson Microelectronics plc – Stereo CODEC with Speaker Driver

WM8976
Production Data
RECOMMENDED POWER UP/DOWN SEQUENCE
In order to minimise output pop and click noise, it is recommended that the WM8976 device is
powered up and down using one of the following sequences:
Power-up when NOT using the output 1.5x boost stage:
1. Turn on external power supplies. Wait for supply voltage to settle.
2. Mute all analogue outputs.
3. Set L/RMIXEN = 1 and DACENL/R = 1 in register R3.
4. 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.
5. Set BIASEN = 1 in register R1.
6. Set L/ROUT1EN = 1 in register R2.
7. Enable other mixers as required.
8. Enable other outputs as required.
9. Set remaining registers.
Power-up when using the output 1.5x boost stage:
1. Turn on external power supplies. Wait for supply voltage to settle.
2. Mute all analogue outputs.
3. 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.
4. Set BUFDCOPEN = 1 and BUFIOEN = 1 in register R1.
5. Set SPKBOOST = 1 in register R49.
6. Set VMIDSEL[1:0] to required value in register R1. Wait for the VMID supply to settle. *Refer
notes 1 and 2.
7. Set L/RMIXEN = 1 and DACENL/R = 1 in register R3.
8. Set BIASEN = 1 in register R1.
9. 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):
1. Mute all analogue outputs.
2. Disable Power Management Register 1. R1 = 0x00.
3. Disable Power Management Register 2. R2 = 0x00.
4. Disable Power Management Register 3. R3 = 0x00.
5. Remove external power supplies.
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PD, Rev 4.5, November 2011
80