COR and Disable Input Range
20.0
6.5
4.5
0.0
On State
Off State
Audio In
Audio Out
Test Point A/D1
to uProcessor
0 V
0 V
0 V
0 V
Test Point
Aud 1
Test Point
A/D 1
Pin 2
of U11
Figure 1. Sample Waveforms for Alignment
Audio In TP Aud 1 Pin 2 TP A/D 1
1 KHz 2 V p-p 1 V p-p 0.1 V
3 KHz 2 V p-p 1 V p-p 2.0 V
5 KHz 2 V p-p 1 V p-p 3.5 V
Op Amp
with variable
gain
High Pass Filter
High Pass Filter
with gain and
rectifier
