WM8976 Wolfson Microelectronics Ltd., WM8976 Datasheet - Page 77

• Manufacturer Part Number: WM8976
• Description: The WM8976 is a low power, high quality stereo codec designed for portable applications such as Digital still camera or Digital Camcorde
• Manufacturer: Wolfson Microelectronics Ltd.

Pre-Production
RECOMMENDED POWER UP/DOWN SEQUENCE
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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.
2.
3.
4.
5.
6.
7.
8.
9.
Power-up when using the output 1.5x boost stage:
1.
2.
3.
4.
5.
6.
7.
8.
9.
10. Enable other mixers as required.
11. Enable other outputs as required.
12. Set remaining registers.
Power Down (all cases):
1.
2.
3.
4.
5.
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.
Enable other mixers as required.
Enable other outputs as required.
Set remaining registers.
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.
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.
Set L/ROUT1EN = 1 in register R2.
PP Rev 3.0 April 2006
WM8976
77