AM625:USB0 does not work intermittently after repeatedly turning it on and off.

Hello iris kang

Thank you for the query.

I'm having issues with USB0 being recognized, and then once it's not recognized, it won't come back to life no matter how many times I turn it on and off.

Please elaborate.

Are you switching off the SOC power or the VBUS input to SOC VBUS

Do you have any capacitors on the VBUS input on the SOC board?

Regards,

Sreenivasa

Hello iris kang

Refer below additional input from the device expert.

The snapshot they inserted doesn’t show any capacitance on VBUS.  If that is the case, the voltage applied to our VBUS input should drop almost instantly since the signal trace is the only capacitance and it would be discharged to ground via the 30k ohm path through the voltage divider circuit.

 Is there a chance they are using a Type-C cable with an active circuit that has a capacitor connected to VBUS.  Ask which end of the cable is being plugged and unplugged.  If they are plugging and unplugging the host end, ask if they get the same result when plugging and unplugging the device end.

Regards,

Sreenivasa

Hello, Kallikuppa Sreenivasa

In this circuit, there is no capacitor on the VBUS line.
I tried adding 10 nF, with the same result.

I also tested the circuit with the generator diode removed, and it works fine.

I think there shouldn't be any problem with removing the Zener diode, so I'm going to remove it and use it.

Best regards,

Iris Kang.

Hello iris kang

Thank you.

iris kang said:

I also tested the circuit with the generator diode removed, and it works fine.

I think there shouldn't be any problem with removing the Zener diode, so I'm going to remove it and use it.

Help me understand what you meant by generator diode.

Regards,

Sreenivasa

Hello, Kallikuppa Sreenivasa

There was an error in the translator: generator diode -> zener diode.

Best regards,

Iris Kang.

Hello iris kang

Thank you.

I guess you removed D103. 

Regards,

Sreenivasa

Hello iris kang

I am closing the thread.

Please reply the above query when you get a chance.

Regards,

Sreenivasa

Hello, Kallikuppa Sreenivasa

You are correct that you removed D103,

I still have the problem when testing after further removal.

It happens more when the data lines are connected but only the VBUS is disconnected (using a USB hub).

Let me know if there is anything else I can look into.

Best regards,

Iris Kang.

Hello iris kang

Thank you for the inputs.

iris kang said:

It happens more when the data lines are connected but only the VBUS is disconnected (using a USB hub).

I suspect this is not a valid use case.

I would expect the VBUS to be applied before the data lines connect.

Can you  please follow the recommendations and let me know if this helps.

Regards,

Sreenivasa