Limiter shows weird behaviour after Reset in ADAU1452


i am using a limiter in an ADAU1452 hardware project. After every reset of the adau1452 and loading of the dsp programm and parameter the limiter starts with <-70dB gain and then slowly over several minutes runs up to 0 dB gain. This happens even for small input signals.


It shows that the behaviour is dependant of the decay value.

The higher the value the slower the gain moves up.

This can be reproduced with the evalboard,

Unfortunatly i don't arrive to share the project here, so i only have a screenshot.

My SigmaStudio version is 4.6

Can anyone reproduce this behavior?

And can anyone explain it?

  • Maybe the explanation is that the Decay unit is not dB/s but ms or at least a time.

    The lower the decay the higher is the distortion.

    So decay 8 fits about 10ms and decay 23 about 10 000ms.

    Now i found one remark in the help: 

    Larger values result in longer decays, with 23 never recovering to the original gain.

    Butvi also find the formula:

    Decay dB/s Value stored in RAM = (fs / 26373 * Decay), where “Decay” is the value entered in the block.

    Seems to be some discrepancy between the two definitions in the help.