Audio Codec '97

AC ‘97 Component Specification Revision 2.3 Rev 1.0
86
Digital
DAC
Analog
DAC
I/O
Pad
Digital
ADC
Analog
ADC
I/O
Pad
Digital Analog
AB C DE
AC
Link
FG H IJ
DAC output
ADC input
Figure 26. Loopback points
6.7.1 ADC Loopback '001'
The ADC Loopback takes the line input signal to the ADC and routes it back to the Line output. This loop includes
the analog functions in the receive and transmit path. The path is from the ADC input all the way to point G where
it is then looped back to point B and out to the DAC output.
6.7.2 Local analog Loopback '010'
The appropriate outgoing slot of the AC-link is passed through the DAC and the analog filters, looped back through
the ADC, then onto the appropriate incoming stream slot of the AC-link. This is commonly used in modem modes
to troubleshoot problems. This path is from the link (point A) to point D where it is looped back to point I and back
through the ADC to the link.
6.7.3 DAC Loopback '011'
This digital test loops back the digital transmit path (outgoing stream) to the digital receive path (incoming stream).
This path is from the link (point A) to through the Digital portion of the DAC to point C where it is looped back to
point H and back through the digital section of the ADC.
6.7.4 Remote analog Loopback '100'
The Line input signal is routed back to the Line output. This loop includes the analog receive functions, but no ADC
or DAC. This path is from the ADC input to point J where it is looped back to point E and out to the DAC output.