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Original question:

TPS25751: Do I need to supply 5v if sinking only?

TPS25751: Powering PP5V below 4.9V for Sink-only applications with Vconn support

TG-Techie
Prodigy 10 points
Part Number: TPS25751

Tool/software:


## Background

- Building on Chad Krause's question "TPS25751: Do I need to supply 5v if sinking only?": 

- The USB Type-C Specification permits Vconn to be within 3.0V - 5.5V (Section "2.5 Vconn" in  "USB Type-C Spec R2.4").

- The Recommended Operating Conditions for the PP5V pin in the TPS25751's datasheet (Sections 6.3.1 and 6.3.2) recommend no less than 4.9V and up to 5.5V.

- I’m implementing a single-cell lipo wearable device that's has USB Type-C, is Sink-only, and does need to support VConn Powered Accessories.  At present, that design does not include any form of DC/DC converter to boost the battery voltage up to ~5V.

## Question

Since the application would be Sink-only, do you know of any design contains that would prevent one from supplying a non-boosted battery voltage to the PP5V pin? 

Else, do you have any other recommendations for (near) stand-alone Type-C port controllers similar to the TPS25751 (Debug accessory pin, integrated VConn switch, orientation pin, etc)? 
(And/or does my parsing of the USB Type-C spec match others' understanding)


Best and thank you,
    ~ TG-Techie

  • 0
    TI__Mastermind 37855 points

    Hi TG,

    Thanks for reaching out, we will aim to provide you feedback by the end of the week.

    Thanks and Regards,

    Chris

  • 0 in reply to Christopher Lim1
    TI__Mastermind 37855 points

    Hi TG,

    TG-Techie said:
    Since the application would be Sink-only, do you know of any design contains that would prevent one from supplying a non-boosted battery voltage to the PP5V pin? 

    Per the DS, we do not recommend supplying PP5V with a voltage under 5-V.

    I reached out to the team internally, but we could not find any data points on this.

    Doing some testing in the lab, the PD controller negotiation did not always negotiate correctly when PP5V was set to a voltage less than 5-V, so I would not recommend using the TPS25751 in the application you are looking for if this is a requirement.

    I tested at 5-V, 4.5-V, 4.2-V, 4-V, and 3.5-V. 4.5-V seemed the best, with a PD negotiation sometimes correctly negotiating. At the lower voltages, it appeared that the PP5V voltage was too low for the TPS25751 as Hard Resets would occur. 

     

    Unfortunately, I do not know of a device that supports your requirements.

    Thanks and Regards,

    Chris