TPS25751: TPS25751's SOP' communication capability

Hi Zong,

zong xu said:

1. Is TPS25751 SOP' communication capable? I believe it's yes since TPS25751 is capable to deliver 20V/5A.

Yes, the TPS25751 is SOP' capable.

zong xu said:

2. For TPS25751, the SOP' communication happens before source capability advertisement or after explicit PD contract establishment?

Yes, the TPS25751 will send SOP' communication before source capability advertisement.

zong xu said:

3. Is there a designated register to contain the electronically marked cable's  response to a SOP' communication (discover identity command)? just like TPS65988's register 0x48/49, I didn't make it to find that in TPS25751's TRM and datasheet.

No, as you have noticed, the TPS25751 does not have a register that contains the cable's response.

Thanks and Regards,

Chris

Hi Chris,

Thanks for your timely reply.

Based on the fact that TPS25751 does not have a register that contains the cable's response, is there a way for TPS25751 to distinguish the attached cable? If not, could you please recommend an alternative for TPS25751, many thanks!

Requirement: The application needs TPS25751 to source 5V/3A to sink device when the authorized cable is attached, but source 5V/0.5A when the unauthorized cable attached

BR

Zong,

Why would you only want to provide higher power based off of vendor ID cable response? I've seen cases where the source checks the SOP for it's ID, but I haven't seen your case before.

Thanks and Regards,

Chris

Hi Chris,

The context is that the FG level product we are buiding has a mated cable, the product will source 5V/0.5A by default with normal cable, and when the mated cable attached, it will source higer power.

It doesn't have to be the vendor ID in cable response to discover identity command from source, it can be any activity as long as the host can be notified that the mated  cable is attached.

And that's why originally i want to confirm whether there is any register which contain the cable response to SOP'.

Hi Zong,

Thanks for the clarification. Could you also check SOP? Is there a specific reason you need SOP'? I would assume the product also has a specific VID?

I still don't think there is a register that will provide you the VID for SOP or SOP' in the TPS25751, but let me double check with the team and get back to you.

Thanks and Regards,

Chris

Hi Chris,

Is there a specific reason you need SOP'? 

Reply: based on the premise that it need to distinguish the mated cable from other cables, and yes, the mated cable does have a VID; regarding the fact that cable VID is usually stored in the cable's discover identity command response via SOP', that's why i originally focus on SOP'.

And you remind me the possibility of SOP to achieve it, and i will double check that in USB PD specification, and thanks for your effort and we can perform this investigation in parallel.

BR

Hi Zong,

I'm still waiting from feedback from the team and will try to give you an update by the end of the week.

Thanks and Regards,

Chris

Hi Chris,

Thanks for your help!

and is there any progress? TPS25751 is the alternative for TPS65988, Since TPS65988 has register(0x48/49) to contain the cable response, i'm inclined to that TPS25751 also has the same capability. Anyway, looking forward to your reply.

BR

Hi Chris,

Appreciated and it really helps a lot.

and regarding the fact that the Discover Identity Command & Discover Identity Command ACK is sent and received via SOP, which means it happens after an explicit contract has been established.

I would like to confirm that TPS25751 will send Discover Identity Command by default, or need host to inform TPS25751 to send the command after explicit contract established.If it need host involvement, could you please also kindly share the detailed steps to achieve it.

Sorry for reaching out so frequently and thanks in advance.

BR