CS4235 Datasheet, PDF (78/94 Pages) Cirrus Logic – CrystalClear Low Cost ISA Audio System

VDF1 through VDF3 provide power to internal
digital sections of the codec and should be qui-
eter than VD1. This can be achieved by using a
ferrite bead to the VD1 supply.
VA provides power to the sensitive analog sec-
tions of the chip and should have a clean,
regulated supply to minimize power supply cou-
pled noise in the analog inputs and outputs.
ADC/DAC FILTER RESPONSE PLOTS
Figures 25 through 30 show the overall fre-
quency response, passband ripple, and transition
band for the ADCs and DACs. Figure 31 shows
the DACs’ deviation from linear phase. Since the
filter response scales based on sample frequency
selected, all frequency response plots x-axis are
shown from 0 to 1, where 1 is equivalent to Fs.
Therefore, for any given sample frequency, mul-
tiply the x-axis values by the sample frequency
selected to get the actual frequency.
CS4235
CrystalClear ^TM Low Cost ISA Audio System
10
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
Input Frequency ( x Fs)
Figure 25. ADC Filter Response
0.2
0.1
0.0
-0.1
-0.2
-0.3
-0.4
-0.5
-0.6
-0.7
-0.8
0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40 0.45 0.50
Input Frequency ( x Fs)
Figure 26. ADC Passband Ripple
78
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
0.40
0.45
0.50
0.55
0.60
0.65
0.70
Input Frequency ( x Fs)
Figure 27. ADC Transition Band
DS252PP2