WM8731 / WM8731L
Production Data
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 SEQUENCE
•
Switch on power supplies. By default the WM8731 is in Standby Mode, the DAC is
digitally muted and the Audio Interface and Outputs are all OFF.
•
Set all required bits in the Power Down register (0Ch) to ‘0’; EXCEPT the OUTPD
bit, this should be set to ‘1’ (Default).
•
•
•
Set required values in all other registers except 12h (Active).
Set the ‘Active’ bit in register 12h.
The last write of the sequence should be setting OUTPD to ‘0’ (active) in register
0Ch, enabling the DAC signal path, free of any significant power-up noise.
POWER DOWN SEQUENCE
•
•
Set the OUTPD bit to ‘1’ (power down).
Remove the WM8731 supplies.
PD, Rev 4.8, April 2009
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