Datasheet

0
–20
–40
–60
–80
–100
–120
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
Magnitude – dB
FrequencyNormalizedtof
S
ADCChannelResponseforDecimationFilterC
(RedLineCorrespondsto –60dB)
TLV320AIC3100
SLAS667A –NOVEMBER 2009–REVISED MAY 2012 www.ti.com
5.4.4.4.3 Decimation Filter C
Filter C along with an AOSR of 32 is specially designed for 192-ksps operation for the ADC. The pass
band, which extends up to 0.11 × f
S
(corresponding to 21 kHz), is suited for audio applications.
Table 5-23. ADC Decimation-Filter-C Specifications
Parameter Condition Value (Typical) Unit
Filter gain from 0 to 0.11 f
S
0…0.11 f
S
±0.033 dB
Filter gain from 0.28 f
S
to 16 f
S
0.28 f
S
…16 f
S
–60 dB
Filter group delay 11/f
S
s
Pass-band ripple, 8 ksps 0…0.11 f
S
0.033 dB
Pass-band ripple, 44.1 ksps 0…0.11 f
S
0.033 dB
Pass-band ripple, 48 ksps 0…0.11 f
S
0.032 dB
Pass-band ripple, 96 ksps 0…0.11 f
S
0.032 dB
Pass-band ripple, 192 ksps 0…20 kHz 0.086 dB
Figure 5-15. ADC Decimation-Filter-C Frequency Response
5.4.4.5 ADC Data Interface
The decimation filter and signal processing block in the ADC channel pass 32-bit data words to the audio
serial interface once every cycle of ADC_f
S
. During each cycle of ADC_f
S
, a pair of data words (for left
and right channel) is passed. The audio serial interface rounds the data to the required word length of the
interface before converting to serial data. Because the TLV320AIC3100 has only a mono ADC, it passes
the same data to both the left and right channels of the audio serial interface.
5.4.5 Updating ADC Digital-Filter Coefficients During Record
When it is required to update the ADC digital-filter coefficients during record, care must be taken to avoid
click and pop noise or even a possible oscillation noise. These artifacts can occur if the ADC coefficients
are updated without following the proper update sequence. The correct sequence is shown in Figure 5-16.
The values for the times listed are conservative and should be used for software purposes.
40 APPLICATION INFORMATION Copyright © 2009–2012, Texas Instruments Incorporated
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