STUSB4500 Dual power supply and communication circuitry enabling option using ATTACH pin

[AV.6]

Hi,

in STUSB4500 if we are planning to use the chip for Power delivery and communication enabling circuit, then will it be necessary to do adjustments in the Vbus when and external 3v3 is applied to the Vsys pin.

In case of a Power delivery available port, then the Vbus will be able to power up the Vdd.

But in case of a non PD cable comes in contact for communication, for the ATTACH and AB_side detection, wont we require an external power on the Vsys pin..?

whether the ATTACH and AB_ Side pin wont be sufficient for communication circuit triggering.?

Have anyone tried this usecase for the STUSB4500.?

DO you have any suggestions on the same..?

Please share your views on this..

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Best regards,

Akshay Vavukkal

[Winfred LU]

STUSB4500 can be supplied in 3 different ways.

In your application, the ways being used is to be supplied through the VDD and VSYS pins for applications powered by VBUS with a system power supply delivering 3.3 V.

There seems to be no need for adjustments in VBUS.

Please refer to STEVAL-ISC005V1, where VSYS is connected to 3V3.

https://www.st.com/content/st_com/en/products/evaluation-tools/solution-evaluation-tools/psu-and-converter-solution-eval-boards/steval-isc005v1.html

[AV.6]

Hi Winfred,

If I use Vsys as an external supply and do not give power for Vdd at all,

Will the STUSB negotiations take place ..?

Will the AB_Side output be obtained as cable Is connected in the port..?

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Thanks & Regards,

Akshay V

[Winfred LU]

>If I use Vsys as an external supply and do not give power for Vdd at all,

According to datasheet it shall also work properly, although in most cases STUSB4500 should be powered by VDD pin only.

>Will the AB_Side output be obtained as cable Is connected in the port..?

No. But, ATTACH pin can be used instead.

This pin is asserted when a valid source-to-sink connection is established.