WM8976 Wolfson Microelectronics Ltd., WM8976 Datasheet - Page 25

• 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
ANALOGUE TO DIGITAL CONVERTER (ADC)
Figure 10 ADC Digital Filter Path
w
Figure 9 Microphone Bias Schematic
ADC DIGITAL FILTERS
Table 11 ADC Enable Control
The WM8976 uses a multi-bit, oversampled sigma-delta ADC. The use of multi-bit feedback and
high oversampling rates reduces the effects of jitter and high frequency noise. The ADC Full Scale
input level is proportional to AVDD. With a 3.3V supply voltage, the full scale level is 1.0V
voltage greater than full scale may overload the ADC and cause distortion.
The ADC filters perform true 24 bit signal processing to convert the raw multi-bit oversampled data
from the ADC to the correct sampling frequency to be output on the digital audio interface. The
digital filter path for each ADC channel is illustrated in Figure 10.
The ADC is enabled by the ADCENL/R register bit.
R2
Power
management 2
REGISTER
ADDRESS
VMID
0
BIT
ADCENL
LABEL
internal
resistor
internal
resistor
0
DEFAULT
AGND
Enable ADC:
0 = ADC disabled
1 = ADC enabled
MB
DESCRIPTION
MBVSEL=0
MICBIAS
= 1.8 x VMID
= 0.9 x AVDD
MBVSEL=1
MICBIAS
= 1.3 x VMID
= 0.65 x AVDD
PP Rev 3.0 April 2006
WM8976
rms
. Any
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