Cirrus Logic AN331 - Manual (Page 3)

AN331
3
3. Recommended Analog Input Buffers for the CS5381 in Mono-Mode
An implementation with the CS5381 requires separate input buffer stages for the differential analog inputs. A single
buffer driving both differential inputs has been shown to result in an unacceptable level of distortion. The recom-
mended buffer topologies are nearly identical to that shown on the CS5381 evaluation board, CDB5381. The sche-
matic in Figure 2 is a suggested buffer implementation for the equation e
o
= A/2 + B/2. Notice that the AIN+
connection is routed to the AINR+ and the AINL+, and the AIN- connection is routed to the AINR- and the AINL-
which results in the signals being in-phase.
Figure 2. CS5381 Recommended Buffer Implementation for Non-inverting Configuration
VQ
10 k Ω
10 k
Ω
+
634
Ω
634 Ω
91 Ω
91 Ω +
-
-
2700 pF
470 pF
470 pF
COG
COG
10 uF
10 uF
AINL+
AINL-
COG
+
634 Ω
634
Ω
91
Ω
91 Ω +
-
-
2700 pF
470 pF
470 pF
COG
COG
AINR+
AINR-
COG
AIN-
100 k Ω
AIN+
100 k Ω