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TPD1S514-2EVM: Schematic review and safe failure questions

Jason Rennie
Prodigy 90 points
Part Number: TPD1S514-2EVM
Other Parts Discussed in Thread: TPD1S514, BQ24074

Hi,

Could someone review my TPD1S514 schematic please?

I think it's OK but I'd just like confirmation.

I've configured it in "always on" mode and so I've not connected V_BUS_POWER to anything. And I've used 10uF caps that have at least 2.2uF capacitance at 5v.

I'd also like to know, what happens to the TPD1S514 if it's given more than 30v of DC voltage? 

  • Does it go open circuit?
  • Does it get hot?

Thanks for your help,

Kind regards,

-Jason

ps. the only part number it would accept in this form was the TPD1S514-2EVM

  • 0
    Prodigy 90 points

    I will probably use the TPD1S514-2 because it's cheapest and the BQ24074 can still function even if it's supplied 10v

  • +1 in reply to Jason Rennie
    TI__Genius 11790 points

    Hi Jason,

    You are correct, the device will act in the "always on" mode in the current configuration.  The schematic looks acceptable.  With the 10 uF caps on the system side of the device, I expect you will see more inrush current while charging VBUS_POWER and VBUS_SYS.  It will also take longer to discharge VBUS_SYS than what is shown in datasheet figure 12.  None of this is a major issue - just wanted to provide the information.

    When given more than 30V DC, the device will certainly experience gross failure.  I'm not certain which, but either the TVS surge clamp from VBUS_CON to GND or internal circuitry between the two pins will become overstressed and fail as short circuits.  The resulting inrush current through these pins will cause irreversible damage to the device.

    Regards,
    Eric

  • 0 in reply to Eric Hartigan
    Prodigy 90 points

    Thank you Eric, I appreciate your help.

    It would be great if TI had some info on failure cases at a few different DC voltages. My USB connector is very near my Lipo so I don't want any heat in this area. So I've placed the TPD1S514 a few mm from the connector and the Lipo, and added a footprint for a normal TVS as a fall back, just in case.

    Thanks again for your help.

    -Jason

  • 0 in reply to Jason Rennie
    TI__Genius 11790 points

    Jason,

    Sounds good - glad this solution works for you.  Please reach out if you have any additional questions.

    Regards,
    Eric