WM8985
Pre-Production
AUXILLIARY INPUTS
There are two auxiliary inputs, AUXL and AUXR which can be used for a variety of purposes such as
stereo line inputs or as a ‘beep’ input signal to be mixed with the outputs.
The AUXL/R inputs can be used as a line input to the input BOOST stage which has adjustable gain
of -12dB to +6dB in 3dB steps, with an additional "off" state (i.e. not connected to ADC input). See
the INPUT BOOST section for further details.
The AUXL/R inputs can also be mixed into the output channel mixers, with a gain of -15dB to +6dB
plus off.
INPUT BOOST
Each of the stereo input PGA stages is followed by an input BOOST circuit. The input BOOST
circuit has 3 selectable inputs: the input microphone PGA output, the AUX amplifier output and the
L2/R2 input pin (can be used as a line input, bypassing the input PGA). These three inputs can be
mixed together and have individual gain boost/adjust as shown in Figure 17.
Figure 17 Input Boost Stage
PP, Rev 3.4, October 2006
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
