64 Circuit Descriptions TP9100 Service Manual
© Tait Electronics Limited May 2005
Accessory Audio
Output
The source for the accessory audio output signal CDC AUD TAP OUT is provided
by IC204 (
RAMPDAC ball). The DAC output of IC204 is low-pass filtered to
remove high-frequency artefacts. The low-pass filter, formed by IC201
(pins 1 to 3), R219, R221, R224, C206, C208 and C210, is a third-order
Butterworth type with a cut frequency of approximately 12 kHz.
The output of the low-pass filter is buffered by IC201 (pins 5 to 7), and fed
via R207 and R208 to drive the
CDC AUD TAP OUT interface line. The DC bias
for this signal path is provided by IC204 and is approximately 1.2V when
operational. The offset at
CDC AUD TAP OUT is approximately 1.2V owing to
the gain of the buffer amplifier.
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