Cirrus Logic CDB42L56 - Manual (Page 21)

DS851DB1 21
CDB42L56
6. PERFORMANCE PLOTS
Test conditions (unless otherwise specified): T
A
= 25°C; VA=VCP=VLDO=VL=1.8 V; input test signal is a full-scale
997 Hz sine wave; dB values relative to full-scale output; measurement bandwidth 20 Hz to 20 kHz (un-weighted);
Sample Frequency = 48 kHz; +2 dB analog gain for Line Output path; -4 dB analog gain for Headphone Output path;
Headphone test load: R
L
= 16  ; no LPF option for Headphone Output path.
Note: The total harmonic distortion + noise (THD+N) performance of the ADC in the CS42L56 is determined by
the value of the capacitor on the FILT+ pin. Larger capacitor values yield significant improvement in THD+N
at low frequencies.
Fig. 10 shows the THD+N vs. frequency performance measured with several FILT+ ca-
pacitor values.
-100
-60
-98
-96
-94
-92
-90
-88
-86
-84
-82
-80
-78
-76
-74
-72
-70
-68
-66
-64
-62
d
B
F
S
20 20k 50 100 200 500 1k 2k 5k 10k
Hz
-100
-60
-98
-96
-94
-92
-90
-88
-86
-84
-82
-80
-78
-76
-74
-72
-70
-68
-66
-64
-62
d
B
F
S
-120 -20 -100 -80 -60 -40
dBr
Figure 10. THD+N vs. Freq. - Analog In to Digital Out Figure 11. THD+N vs. Amplitude - Analog In to Digital Out
2.2µF
10µF
22µF
-140
+0
-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
d
B
F
S
20 20k 50 100 200 500 1k 2k 5k 10k
Hz
-140
+0
-130
-120
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
d
B
F
S
20 20k 50 100 200 500 1k 2k 5k 10k
Hz
Figure 12. FFT - Analog In to Digital Out @ -1 dBFS Figure 13. FFT - Analog In to Digital Out @ -60 dBFS