Datasheet

100
4341H–MP3–10/07
AT8xC51SND2C/MP3B
15.3.1 Audio DAC Start-up Sequence
In order to minimize any audio output noise during the start-up, the following sequence should
be applied.
15.3.1.1 Example of power-on: Path DAC to Headset Output
• Desassert the Reset: write 07h at address 10h.
• All precharge and Master on: write FFh at address 0Ch.
• Line Out On: write 30h at address 00h.
• Delay 500 ms.
• Precharge off: write 0Ch at address 01h.
• Delay 1 ms.
• Line Out on, DAC On: write 3Ch at address 00h.
15.3.1.2 Example of power-off: Path DAC to Headset Output
• DAC off: write 30h at address 00h.
• Master off: write 00h at address 0Ch.
• Delay 1 ms.
• All off: write 00h at address 00h
15.3.1.3 Example Start I2S
• Start DCLK.
• RSTMASK=1.
• RESFILZ=0 and RSTZ=0.
• RESFILZ=1 and RSTZ=1.
• RSTMASK=0.
• Delay 5 ms.
• ONDACL=1 and ONDACR=1.
• Program all DAC settings: audio format, gains...
15.3.1.4 Example Stop I2S:
• DAC off: ONDACL=0 and ONDACR=0.
• Stop I2S and DLCK.
15.3.2 Audio PA Sequence
15.3.2.1 PA Power-On Sequence
To avoid an audible ‘click’ at start-up, the input capacitors have to be pre-charged before the
Power Amplifier.
15.3.2.2 PA Power-Off Sequence
To avoid an audible ‘click’ at power-off, the gain should be set to the minimum gain (-22dB)
before setting the Power Amplifier.