AM3352: intermediate potenatial on MDC terminal when power on

takeshi matsuzaki

Expert 2030 points

Part Number: AM3352

Hi
I'd like to know about intermediate potenatial(over VIL and under VIH) while power on sequence.

This wave from is from my customer..

AM335x MDC terminal becomes 0.82V while about 150ms on power on sequence.
This 0.82V comes from their other circut like Pull Up resister or something.

Does this 0.82V of 150ms give any damages to AM335x?
AM335x MDC terminal has Hysteresis Characteristic from AM335x data sheet so I think this will be OK..

Is it OK?

Regards,
Takeshi Matsuzaki

over 7 years ago

0 Biser Gatchev-XID over 7 years ago

TI__Guru**** 393215 points

Hi,

You must ensure that no external voltages are applied to AM335x I/O pins before all AM335x supply voltages have fully ramped up and stabilized. In your case I suspect that this has something to do with the blue signal on the scope picture, however I cannot be more specific without seeing the schematic. My advice is to ask your customer to check in this direction.

0 takeshi matsuzaki over 7 years ago in reply to Biser Gatchev-XID

Expert 2030 points

Hi Biser,

> You must ensure that no external voltages are applied to AM335x I/O pins before all AM335x supply voltages have fully ramped up and stabilized.

This point is clear on the waveform I put because 0.82V of MDC terminal is after PWRONRSTn.

> In your case I suspect that this has something to do with the blue signal on the scope picture,

blue signal has nothing to do with this case.

My question is whether the 0.82V of green signal will damage AM335x or not.

As I mentioned earlier,AM335x MDC terminal has Hysteresis Characteristic.
So I think 0.82V of green sinal won't damage.

Regards,
Takeshi Matsuzaki

0 Biser Gatchev-XID over 7 years ago in reply to takeshi matsuzaki

TI__Guru**** 393215 points

No, in this case there will be no damage to the I/O pin.

0 takeshi matsuzaki over 7 years ago in reply to Biser Gatchev-XID

Expert 2030 points

Biser,
You make me clear, Thanks!

Regards,
Takeshi Matsuzaki

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AM3352: intermediate potenatial on MDC terminal when power on