AM335x GPIO high Impedance Values in Ohm?

Dear Biser,

I just want know what is impedence(in terms value in Ohm) of pin when configured as a General purpose I/O. In both during Power on & off condition.

Best Regards,
Piyush

can i know approx value of high Impedance (in terms value in Ohm) for unpowered device AM335X of GPIO.

ok,
thanks for giving lovely support.

We do not provide this information because it is not a supported use case.

It is not a supported use case because connecting a voltage to an IO with the power turned off may damage the IO.

Regards,
Paul

hello paul,

ofcorse i agree with you.
but in my case i connect RTC chip with AM335x, for RTC chip coin battery cell is mandotary interface.and also i measuring coin battery cell voltage thorough AM335X GPIO.

think about when board is not power up, that time coin battery cell is direct connected with AM355X GPIO. so coin battery cell leakage current flow through this GPIO.

if we know GPIO impedance (in terms value in Ohm), so we can calculate leakage current of coin battery cell, when board is not power up.

regard,
piyush mathukiya

If you apply a voltage to an input pin that is 0.3 volts greater than the respective VDDSHVx power supply pin, an ESD protection diode will forward bias and the voltage source connected to the input will be sourcing current to the entire VDDSHVx power rail. In your case, current would flow from the battery through the internal ESD protection diode back out of the chip to all other devices connected to the respective VDDSHVx power rail.  Therefore it is not possible for me to tell you what the leakage would be into the input.

The internal ESD protection diode was not designed to conduct steady state current.  It is only designed to dissipate energy from ESD events up to the limits defined in the data sheet.

Do not apply a voltage greater than VDDSHVx + 0.3 to an input because it could damage the AM335x device.

Regards,
Paul

Dear paul,

please, can you send me internal circuit of GPIO (AM335X).
so, i can undertand more easily.

Regards,
Piyush

We do not provide a schematic of the IO cell.

An simple equivalent circuit for the unexpected current flow would be through a shottky diode connected between the input terminal and the respective VDDSHVx power supply terminal, where the Anode is connected to the input terminal and Cathode is connected to the respective VDDSHVx terminal.

Regards,
Paul