TAS6422-Q1: DC Load Diagnostic: About Open load Detection

Hi 

 Both DC and AC diag can't be used during PLAY state. Your testing results are correct. Only Real Time Load Diag could detect load status during PLAY, but this device doesn't have this feature. 

Göknur Setrekli said:

By the way I can not understand what Channel state DC diagnostics mode in 0x04 was.

Try it during Hi-Z state, and could consider try it with open load, then check 0x0C status. The normal load diag only takes 260ms and finished. Only when there's a fault, will keep in this status.

"Both DC and AC diag can't be used during PLAY state. Your testing results are correct. Only Real Time Load Diag could detect load status during PLAY, but this device doesn't have this feature." Thank you so much this info and feedback. 

"Try it during Hi-Z state, and could consider try it with open load, then check 0x0C status. ."

For you said above I tried the steps below:

1. Check the channel states from  the register 0x0F.

2. If one of them is Hi-Z, set the DC Load diag to the channel which is Hi-Z from the register 0x04..

3. Read  and monitor the diagnostic load states in 0x0C.

But it runs like in CASE 2. I couldn't understand that If the device has not the feature real time open load detection, it already can not be find the channel state in any time, too. Am I wrong?. Can you explain in detail above that you said?

Hi 

Göknur Setrekli said:

it already can not be find the channel state in any time, too. Am I wrong?. Can you explain in detail above that you said?

If the device already into PLAY state, and open load appears, then indeed there's no way for the device to detect it. Only the open load condition happens before device PLAY, could be detected.

But if it is short circuit, the OC protection would take effect, and device reprot FAULT. Then even you try to reset the device or clear the fault, the DC Load Diag will take effect, and detected there's still short ciruit, it won't back into PLAY.

Hi,

But if it is short circuit, the OC protection would take effect, and device reprot FAULT. Then even you try to reset the device or clear the fault, the DC Load Diag will take effect, and detected there's still short ciruit, it won't back into PLAY.

Yes, I have obtained the similar results for the short circuit. If the device is begin to run whose the load is shorted to GND, Amplifier is reported that it was shorted to GND. After the removed the jumper between GND and the load, it iwas run in PLAY and reported No Shorted to GND. But If it is begin to run in PLAY and normally, It could not be detect it even if I have shorted it to GND later and then didn't back to  PLAY.

I only tried AC diagnostic mode for open load detection. But it wasn't useful and effective because it has to be change channel state to Hi-Z and need to operate out of  its functionality itself even if I use the its sound as a test signal. 

Thanks a lot your feedback.

Yes I could test and read some impedance values of the load both when it was connected and when it was not  as follwing the step in the datasheet. (using the sound itself  for experimental purposes. the sound is very complex, whose the frequency band is wide.).  

Acc. to thedatasheet, "When the test is complete the channel reporting register indicates the status change from the AC diagnostic
mode to the Hi-Z state. The detected impedance is stored in the appropriate I2C register." So I waited to change of the CH state and then read the impedance. But it takes a time a bit ,It stays in MUTE until the changing the CH state That's why I don't find it practical term as its functionality.

Thanks a lot your all responses and for taking the time. Although I cannot perform real-time open load detection or any DC diagnostic etc., I now recognize the component."