WM8994 Datasheet, PDF (144/359 Pages) Wolfson Microelectronics plc – Multi-Channel Audio Hub CODEC for Smartphones

WM8994
Production Data
The line outputs incorporate a common mode, or ground loop, feedback path which provides rejection
of system-related ground noise. The return path, via LINEOUTFB, is enabled separately for
LINEOUT1 and LINEOUT2 using the LINEOUT1_FB and LINEOUT2_FB bits as defined in Table 77.
Ground loop feedback is a benefit to single-ended line outputs only; it is not applicable to differential
outputs, which already inherently offer common mode noise rejection.
REGISTER BIT
ADDRESS
LABEL
DEFAULT
DESCRIPTION
R55 (0037h) 7 LINEOUT1_FB
Additional
Control
0
Enable ground loop noise
feedback on LINEOUT1
0 = Disabled
1 = Enabled
6 LINEOUT2_FB
0
Enable ground loop noise
feedback on LINEOUT2
0 = Disabled
1 = Enabled
Table 77 Line Output Ground Loop Feedback Enable
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PD, April 2012, Rev 4.4
144