HD3SS3220: Diode on VDD5 when powered from VBUS

Shmuel Davis

Part Number: HD3SS3220
Other Parts Discussed in Thread: TUSB320

In the following thread :-

Since the VDD5 for the HD3SS3220 I am powering from VBUS it was recommended that I use a diode similar to the implementation shown for the TUSB320 UFP configuration

1. What is the purpose of this diode for the HD3SS3220 ?

2. As far as I understand the VBUS range is 4.75V - 5.5V. If VBUS drops close to 4.75 won't the diode drop the VDD5 for the HD3SS3220 to below 4.5V min ?

Thank you

Shmuel

over 7 years ago

0 Michael.Walker over 7 years ago

TI__Mastermind 19720 points

That E2E post is incorrect HD3SS3220 does not need the diode and can be attached directly to VBUS.
The Diode is there for the TUSB320 so that the VBUS voltage range(4.75V to 5.5V) is dropped down to a safe voltage range between spec of the TUSB320(2.7V to 5V). The HD3SS3220 actually integrates this diode internally so that the device can be attached directly to VBUS because they have compatible voltage ranges(4.75V to 5.5V for VBUS and 4.5V to 5.5 for HD3SS3220).

0 Shmuel Davis over 7 years ago in reply to Michael.Walker

Expert 2930 points

Thank you so much, Maybe someone should tell Expert Jorge Llamas about the mistake !!!!!

Also I sent my schematic to be reviewed by TI and this was not picked up on ????

0 Michael.Walker over 7 years ago in reply to Shmuel Davis

TI__Mastermind 19720 points

I have updated the thread that was incorrect.

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HD3SS3220: Diode on VDD5 when powered from VBUS