Cirrus Logic CS470xx - Manual (Page 22)

DS787PP9 22
5.16 ADC Characteristics
5.16.2 Analog Input Characteristics (Automotive)
Test Conditions (unless otherwise specified): TA = –40–85°C; VDD = 1.8V±5%, VDDA (VA) = 3.3V±5%; kHz sine wave
driven through the passive input filter (R
i
= 10 k ) in Fig. 5-13 or Fig. 5-14 ; DSP running test application; Measurement
Bandwidth is 10 Hz–20 kHz.
1. dB units referred to the typical full-scale voltage.
2. These full-scale values were measured with R
i
=10k for both the single-ended and differential mode input circuits.
3. The full-scale voltage can be changed by scaling R
i
.
Differential Full-Scale (Vpp) = 3.7*VDDA*(Ri+200)/(10k+200)
Single-Ended Full-Scale (Vpp) = 1.85*VDDA*(Ri+200)/(10k+200)
4. Measured between AIN_xx+ and AN_xx–.
5. Measured between AIN_xx+ and AGND.
6. Decreasing full-scale voltage by reducing R
i
causes the noise floor to increase.
7. Common mode input current should be kept to less than ±160uA to avoid performance degradation: |(I
ip
+I
in
)/2| < 160uA. This corresponds to ±1.6V
for R
i
=10 k  in the differential case.
8. This number was measured using perfectly matched external resistors (R
i
). Mismatch in the external resistors typically reduces CMRR by 20 log
(|

R
i
|/R
i
+ 0.001).
9. C
L
represents the parasitic load capacitance between R
i
on the input circuit and the input pin of the CS47048 package.
10. This measurement is not applicable to the CS47028 and CS47024 devices.
Figure 5-13. ADC Single-ended Input Test Circuit
Differential Single-ended
Parameter Min Typ Max Min Typ Max Unit
Fs = 96 kHz
Dynamic Range
1,6,7
A-weighted
Unweighted
40 kHz bandwidth unweighted 97
94
—
105
102
99
—
—
— 94
91
—
102
99
96
—
—
— dB
dB
dB
Total Harmonic Distortion + Noise 6,7
–1 dB
–20 dB
–60 dB
40 kHz bandwidth –1 dB —
—
—
— –98
–82
–42
–90 –90
—
—
—
—
—
—
— –95
–79
–39
–90 –87
—
—
—
dB
dB
dB
dB
AIN_1A/B Interchannel Isolation 10 — 95 — — 95 — dB
AID_[2.6]A/B MUX Interchannel Isolation — 95 — — 95 — dB
DC Accuracy
Interchannel Gain Mismatch — 0.1 — — 0.1 — dB
Gain Drift — ±120 — — ± 120 — ppm/°C
Analog Input
Full-scale Input Voltage 2,3 3.3 3.7 • VA 3.9 1.65 1.85 • VA 1.95 V
PP
Differential Input Impedance 4 — 400 — — — — 
Single-ended Input Impedance 5 — — — — 200 — 
Common Mode Rejection Ratio (CMRR) 8 — 60 — — — — dB
Parasitic Load Capacitance (C
L
) 9 — — 20 — — 20 pF
10µF
C
L
R
i AIN
100K
AIN_xA+
AIN_xB+
or
+