Cirrus Logic AN314 - Manual (Page 7)

AN314REV1 7
AN314
Figure 6. 2-input, Single-ended-to-differential, Multiple Input Range, Multiplexed System
In Figure 6 , the differential device, CS5560, is multiplexed between two inputs which use single-ended-to-differential
conversion circuits. As illustrated, each of these circuits can be configured to attenuate or amplify the single-ended
input signal to use the full-scale range of the converter which is differentially ±4.096V. C4 is an optional capacitor
which can be used to attenuate out-of-band noise to improve overall noise performance. The corner frequency with
the components shown is 18 kHz. The 100 pF to 150 pF capacitors in the feedback of each amplifier are required
to compensate for the capacitive load of the 4700 pF capacitors on the inputs of the multiplexer. The 4700 pF ca-
pacitors provide a charge reservoir for the switched-channel capacitance of the multiplexer and also provide dynam-
ic input current when the converter samples.