
AS3515 V15
austriamicrosystems
Data Sheet, Confidential
www.austriamicrosystems.com
Revision 3.1
24
- 66
6.7
Audio Output Mixer
6.7.1
General
The mixer stage sums up the audio signals of the following stages
Microphone Input 1
Microphone Input 2
Line Input 1
Line Input 2
Digital Audio Input (DAC)
The mixing ratios have to be with the volume registers of the corresponding input stages. Please be sure that the input signals of the
mixer stage are not higher than 1Vp. If summing up several signals, each has of course to be lower.
This shall insure that the output signal is also not higher than 1Vp to get a proper signal for the output amplifier. This stage has an
automatic gain control, which automatically avoids clipping.
6.7.2
AGC
The audio mixer includes an AGC, which is limiting the signal to 1Vp. The AGC has 12 steps with a dynamic range of about 18dB. The
AGC is ON by default but can be disabled by a register bit.
6.7.3
Register Description
The mixer stage has no direct associated registers.
Enabling the Summing / Mixer stage is done via a control bit in the audio settings register (AudioSet1 register 0x14h). Disabling the AGC
is done via AudioSet2 register (0x15h).
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