WM8774
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EXTERNAL CIRCUIT CONFIGURATION
In order to allow the use of 2V rms and larger inputs to the ADC and AUX inputs, a structure is used
that uses external resistors to drop these larger voltages. This also increases the robustness of the
circuit to external abuse such as ESD pulse.
Figure 32 shows the ADC input multiplexor circuit with external components allowing 2Vrms inputs to
be applied.
5K
AINOPL
AINVGL
10uF 10K
AIN1L
10uF 10K
AIN2L
10uF 10K
AIN3L
10uF 10K
AIN7L
10uF 10K
AIN8L
5K
SOURCE
AINOPR
SELECTOR
INPUTS
AINVGR
AIN1R
10uF 10K
10uF 10K
10uF 10K
AIN2R
AIN3R
10uF 10K
10uF 10K
AIN7R
AIN8R
Figure 32 ADC Input Multiplexor Confiuration
10K
DAC
AUX
BYPASS
INPUTS
MX[0]
MX[1]
MX[2]
10uF
DACL/R
10K
10K
10K
AUXL/R
BYPASSL/R
Figure 33 5.1 Channel Input Multiplexor Configuration
PP Rev 1.0 June 2002
38
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
