AM4372: Capacitor value connectable to LVCMOS pin

Sh.Sasaki

Guru 13625 points

Part Number: AM4372

Hi everyone,

My customers are considering connecting capacitors to the LVCMOS pins(For example, GPIO pins) for noise removal.

Since I had problems with the following links before,

I would like to know the value of connectable capacitors.

e2e.ti.com/.../738309

Best regards,
Sasaki

over 7 years ago

0 Biser Gatchev-XID over 7 years ago

TI__Guru**** 393215 points

Hi,

This depends on a lot of factors: whether the I/O is input or output, what is the signal frequency, pinmux mode, just to mention a few. Customers will need to calculate the capacitor value according to pin usage. There is universal recommended value.

0 Sh.Sasaki over 7 years ago in reply to Biser Gatchev-XID

Guru 13625 points

Hi Biser-san,

Thank you for your quick reply.

I/O is input.
I don't know the frequency.
The pinmux mode is various. (Such as GPIO

Could you tell me the formula for calculating it?

Best regards,

Sasaki

0 Biser Gatchev-XID over 7 years ago in reply to Sh.Sasaki

TI__Guru**** 393215 points

Dear Sasaki-san,

This is a standard RC low-pass filter. Formulas are widely available on the internet, e.g. en.wikipedia.org/.../RC_circuit

0 Sh.Sasaki over 7 years ago in reply to Biser Gatchev-XID

Guru 13625 points

Hi Biser-san,

Thank you for your support.

I will check it.

By the way, do you know the reason why the voltage did not go up to 1 V when 0.5 u capacitor was connected with the following link?

e2e.ti.com/.../738309

Like this link, my customers are worried about the problem that voltage does not rise.

Best regards,

Sasaki

0 Biser Gatchev-XID over 7 years ago in reply to Sh.Sasaki

TI__Guru**** 393215 points

I think JJD gave a good explanation on the link you mention. If you are asking about a different pin, we need to know all the details to give a good explanation.

0 Sh.Sasaki over 7 years ago in reply to Biser Gatchev-XID

Guru 13625 points

Hi Biser-san,

Thank you for your support.

I will organize the questions again.

Best regards,

Sasaki

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AM4372: Capacitor value connectable to LVCMOS pin