AM4372: Sink current of AM4372 EXTINTn pin at high temperature

Sh.Sasaki

Other Parts Discussed in Thread: AM4372

Hi,

Does the sink current in the AM4372's EXTINTn pin increase at high temperature?

When turning on the board when the device temperature is about 80 ℃, this pin on my customer's board will only rise up to about 1V.

The circuit and wave form are as follows.

Best regards,

Sasaki

over 5 years ago

0 Biser Gatchev-XID over 5 years ago

TI__Guru**** 393215 points

Hi,

Have you tried to remove C383?

0 Sh.Sasaki over 5 years ago in reply to Biser Gatchev-XID

Guru 13625 points

Hi Biser-san,

Thank you for your reply.

My customer tried to remove R and C from the board and it got up to 3.3V without any problem.

However, they can not remove this C due to the power sequence.

So I have a question.

Why does not it rise to 3.3 V when C is present?
Is there a recommended design method for this pin?
If so, where is it being described?

Best regards,

Sasaki

0 Biser Gatchev-XID over 5 years ago in reply to Sh.Sasaki

TI__Guru**** 393215 points

This capacitor has nothing to do with the power sequence and should not be mounted. Refer to the AM437x GP EVM Rev. 1.5B schematic: processors.wiki.ti.com/.../AM437X_EVM_Boards

0 Sh.Sasaki over 5 years ago in reply to Biser Gatchev-XID

Guru 13625 points

Hi Biser-san,

Thank you for your support.

I have three additional questions.

1) Please let me know principle why this is the case?

2) Is there a pin (other than nNMI) that has the same problem
when connecting a capacitor to AM4372's input pin?

3) A capacitor is prepared for SK board. Is this a design mistake?
My customers are designing boards based on SK.

Best regards,
Sasaki

0 JJD over 5 years ago in reply to Sh.Sasaki

TI__Guru 68880 points

Sasaki, is D3R3V connected to VDDSHV3? The capacitor on the SK board is meant to debounce the push button connected to the interrupt. It looks like you customer is just trying to pull up the NMI (maybe to avoid spurious interrupts), so only the pull up is needed. What is the reason they need to use a cap on another input? What is the application?

Regards,
James

0 Sh.Sasaki over 5 years ago in reply to JJD

Guru 13625 points

Hi James-san,

Thank you for your support.

I ask the customer to remove the CAP.
We will review the details about this issue again, so close the thread once.

Best regards,

Sasaki

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AM4372: Sink current of AM4372 EXTINTn pin at high temperature