TFP401A: maximum current allowed on _PD ESD pin

Keith Keller

Part Number: TFP401A

Hello,

We have an application where we have a TFP401APZP powered from a 3.3V supply and I need to drive the _DP input from a 5.0V source.

To protect the _DP input from an over-voltage/current condition I’ve added a series resistor to limit the input current into the _DP pin.

I am relying on the internal ESD diode to clamp the input voltage to a safe level.

However the datasheet does not have a specification on the current capacity of the ESD diodes on these input pins.

Can you help us determine what the maximum current capacity of the internal ESD diode is on the _PD pin on the TFP401APZP?

Thank you, Keith

over 6 years ago

0 Elias Villegas M. over 6 years ago

TI__Guru* 76130 points

Hello,
The inputs will not tolerate +5V, you should clamp the PD# input to a +3.3 voltage.
Regards

0 Michael Schmitt over 6 years ago in reply to Elias Villegas M.

Prodigy 60 points

I fully understand that they do not tolerate +5V. However I do not have a means to "clamp" the voltage externally to the pin. All I have at this time is a current limiting resistor in-series with this pin. Does the _PD have an ESD protection diode that would clamp the voltage to the VDD rail? If so, what is the current limit of the ESD protection diode? My intent is to set the value of the series resistor to a value to be well bellow the current rating of the ESD diode.

0 Elias Villegas M. over 6 years ago in reply to Michael Schmitt

TI__Guru* 76130 points

Hello,

I'm asking the Design Team for the current rating, we will come here shortly.

Regards

0 Michael Schmitt over 6 years ago in reply to Elias Villegas M.

Prodigy 60 points

Hello Elias,

Has there been any update on the request from the Design Team?

Best Regards,

-Mike

0 Elias Villegas M. over 6 years ago in reply to Michael Schmitt

TI__Guru* 76130 points

Hello,
I've been told that we don't normally specify that, I don't have the current capabilities of the diodes.
There is one evaluation module that uses 33K pull-ups to 3.3V for a high value and shorted to GND for a low value.
Regards

0 Michael Schmitt over 6 years ago in reply to Elias Villegas M.

Prodigy 60 points

Hello Elias,
Yes, I understand that the current capacity is not normally specified as it's not listed in the datasheet, however I was hoping that someone from the design team could provide information on how much current it was designed to support.
I also saw the application in the datasheet with a similar circuit (33K pull-up to 3.3 and shunt to GND). This circuit does not rely on using the ESD diodes at all and I wish I had the opportunity to limit the driver circuit to 3.3V to mimic this configuration.
Best Regards,
-Mike

0 Elias Villegas M. over 6 years ago in reply to Michael Schmitt

TI__Guru* 76130 points

Hello,

I've got feedback from the designer:

"The ESD current handling capability typically for 2KV HBM cell is about 1.3A"

Regards

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TFP401A: maximum current allowed on _PD ESD pin