ALC DC offset calibration problem

We are using the ALC function of the DA7212 with success in several projects.

最近我们试图利用自动直流偏置calibration, accessible through

the ALC_CTRL_1 register.

However, when we have completed this procedure, following the recommended

sequence, the ALC will behave strangely:

- It will, as expected, lower the gain and thus the output volume when high sounds comes in

- It will NOT increase the gain again, unless there is SOME sound coming in.

If the input is quiet, the gain will stay low indefinetly.

We have tried in many ways to remedy this behaviour,

since it will NOT work in our application, but have not succeeded.

For example, playing around with the noise threshold, min and max gains, attack and sustain rates

seem to not affect this problem at all. IF we go to a fully digital ALC, then this problem

goes away, but we need to have analog + digital ALC

Does anyone have an explanation to why this is happening, and a proposed solution?