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USB EZ-PD Type-C

TeMa_2997106
Contributor II

What are the selection criteria for VBUS FET?

If there are guidelines somewhere, please let me know.

- Vgs(Vth)

- Vds

- Id

- Rds(on) : The smaller the better?

If VBUS is fixed at 5V, should Vgs also be 5V?

Thanks,

Tetsuo

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1 Solution
PranavaYN
Moderator
Moderator

Hi,

FET with Vgs(Vth) in -1V to -2.2V range with Id rating based on your application (5A maximum under USB-PD spec) can be selected for the application.

Since VBUS voltage is fixed at 5V, Vds value greater than 5V with the above Vgs(Vth) and Id parameters can be used.

Regards,

Pranava

Best regards,
Pranava

View solution in original post

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4 Replies
PranavaYN
Moderator
Moderator

Hi Tetsuo-san,

We do not have any specific document for selection criteria for VBUS FET.

You can refer to the datasheet of FET used in our CY4532 EVK https://www.vishay.com/docs/66719/si7997dp.pdf .for the parameters.

You can refer to KBA227425 for more information on VBUS FET usage.

Regards,

Pranava

Best regards,
Pranava
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TeMa_2997106
Contributor II

Pranava-san,

Thank you for your reply.

I have already checked the Vishay FET.

This FET has a very large Vgs(20V) and Vds(30V).

If VBUS is fixed at 5V, I think it is not necessary large Vgs/Vds.

Is it correct?

Thanks,

Tetsuo

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PranavaYN
Moderator
Moderator

Hi,

FET with Vgs(Vth) in -1V to -2.2V range with Id rating based on your application (5A maximum under USB-PD spec) can be selected for the application.

Since VBUS voltage is fixed at 5V, Vds value greater than 5V with the above Vgs(Vth) and Id parameters can be used.

Regards,

Pranava

Best regards,
Pranava

View solution in original post

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TeMa_2997106
Contributor II

Pranava-san

Thank you for your support.

I understood all things.

Thanks,

Tetsuo

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