GPIO terminal on AM3352

Hi Nomoto-san,

I cannot understand your question. What do you mean by "input voltage"? Can you explain in more detail?

Hello Biser-san,

Thank you for your reply.

I mean "input voltage" is power supply.
All power pins are not supplied power.

Best Regards,

Nomoto

This is absolutely incorrect usage of the processor. All power rails must be present for the processor to function properly. The only exceptions allowed are listed here: http://processors.wiki.ti.com/index.php/AM335x_Schematic_Checklist#Unused_Power_Rails

Hello Biser-san,

Thank you for your reply.

It may be incorrect usage of the processor, however could you give me a advise for the following circuit?
My customer cannot forward the project.

The followings are explanation for the circuit.
- VccA and VccB are the individual power in each other.
- VccA is power (red line) for Circuit A and AM3352.
- VccB is power (blue line) for Circuit B via FET.
- VccA is off and VccB is on. Therefore, AM3352 is not supplied power.

Under above condition, my customer wants to switch off FET to block the power supply for Circuit B.
Wherein, to know the voltage of Gate of FET, I want to know the GPIO terminal (pad) condition when the power isn't supplied to AM3352.

Best Regards,

Nomoto

There is no circuit attached to your post. You can simply drag-and-drop it in your reply window.

Hello Biser-san,

I apologize to miss the figure.
Now, I attach the figure on the above thread.

Best Regards,

Nomoto

OK, I see it now. For this use case the best solution would be to have external circuitry (pullup/pulldown or buffer) to hold the FET gate at the desired voltage level when AM335X is powered off.

Please also note that no voltages should be present at AM335X I/O pins when the device is powered off. See section 5.1 of the AM335X Datasheet Rev. G, parameter "Steady State Max. Voltage at all IO pins", and Note 8 below the table for details.

Your advice is very helpful for me.

I will tell to my customer.

Best Regards,

Nomoto