Issue with open load detection in PLAY mode.

[Aishwaryaum]

Hi all,

I am facing issue with Open Load detection in PLAY mode and it is working fine in MUTE mode.

I have flashed and tested  the example base code from STM(Autodevkit), Open Load Detection is not working in PLAY mode in this code(Placed the example code snippet below).

In MUTE mode, If either or both speakers are disconnected the signal is updating with value FAULT_OPEN_LOAD_MUTE as shown below-

In PLAY mode, If speakers connected or disconnected also both both conditions the value of signal is updated with "NO_FAULT_PLAY" as shown below-

The structure member "OPENLOAD_PLAY" of structure "FDA_Errors_t" which is getting value from the registers is itself not updating during PLAY mode.

Can anyone help me to come out of this issue.

Thanks,

Aishwarya UM

[ATROI · Accepted solution]

Hi Aishwarya UM

The FDA903D audio amplifier provides the ability to detect the open load even in play.
If the audio signal is judged to be good enough to provide a reliable result, the test result is valid. Otherwise, if the audio signal doesn't allow a reliable detection.
See paragraph (11.4) of the data sheet.
In addition, in the AVAS UM, in paragraph 7.1, step 12,
in the image it is emphasized that the "volume" variable in the demo code must be increased
to overcome the threshold under which the open Load in play detection test is not valid.

Hope this can help.

Thanks,

AutoDevKit Team

[Aishwaryaum]

Hi Atroi,

Thank you for your valuable information.

Even though I am using good quality sound files and even I am trying with different sound files and I have gone thorough your references also and I tried in the same ways but still the open load is not detected during the PLAY mode. So, can I get further more suggestions from your regarding this issue so that I can come out of this.

Thanks & Regards

Aishwarya UM

[Max VIZZINI]

Hi,

Please try changing the volume.

You should find that for certain volume levels the open load is detected while when you decrease the volume then it starts not to be detected.

It is clear that the IC will NOT detect the open in all playback condition.

If you want it to work in all condition, you need to implement a monitoring at the pin looking at the current in audio amp.

Best Regards,

AutoDevKit Team

[Aishwaryaum]

Hi Max VIZZINI,

Thank you for your informative feedback.

Actually I kept vol = 2 as constant and I am not varying it anymore. According to my requirement sound sound increase from 0kmph to 20kmph and decrease from 20kmph to 30kmph. So for this requirement I have kept the volume constant and I am varying the gain based on the speed. For these conditions I am unable detect the openload condition for PLAY mode.

Can you please help me out to figure out this issue.

Thanks & Regards

Aishwarya UM

PREVIEW

[Max VIZZINI]

Hi,

As said, please CHANGE the volume to understand from which level you can detect the Open in Play.

Again, the IC will NOT be able to detect all cases automatically anyway, so the coverage is partial.

For full coverage you need to implement current monitoring.

Best Regards,

AutoDevKit Team