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TPS25740B: GDNG does not stay on

Edgar Laurrence Osis
Prodigy 170 points
Part Number: TPS25740B
Other Parts Discussed in Thread: TPS25810, TPS25740, TPS25740A, TPS2514A, TPS65987D

Hi! I am using TPS25740B for a 5V/3A charger application.

I have a problem with the GDNG pin as it turns on and off. Upon checking the datasheet, the GDNG will output a square wave when

1) it detects a short between the VBUS and GND, and

2) when the junction temperature Tj exceeds Tj1.

When I checked, my VBUS and GND are not shorted and the IC is not hot.

What may be the other cause for the continuous turning on and off of the GDNG?

  • 0
    TI__Mastermind 27605 points

    Hello Edgar,

    Are you only source 5V/3A? If so, why are you using the TPS25740B instead a Type-C controller like the TPS25810. The TPS25740B is intended for power delivery applications where greater than 5V is required.

    What is the source that you have plugged into the external FET connected to the TPS25740B? If you only have 5V connected, you could be triggering a UVP event. THE TPS25740B is designed to advertise either 5V/9V/15V/20V or 5V/9V/12V/15V depending on the connection to HIPWR. The TPS25740B will advertise these PDO's to the sink device regardless of what is connected as the source. So if you connect a sink device, the TPS25740B will advertise that it can source 5V/9V/15V/20V or 5V/9V/12V/15V. The sink device can then decide it would like to sink 20V from the TPS25740B, send the request to the TPS25740B and then 20V is supposed to be presented on VBUS. However, if this doesn't happen and VBUS stays at 5V, the TPS25740B will read this as a under voltage event.

    If you would like to have a Type-C charger that can only source 5V/3A, I would recommend using the TPS25810

  • 0 in reply to Adam Mc Gaffin
    Prodigy 170 points

    Hi! Sorry for the late reply.

    I see now why the GDNG pin is showing a series of pulses instead of a step waveform. I am using only a 5V, 3A source because I thought that the voltages displayed are individually advertised. And also, I used TPS25740B because I thought that it can be incorporated into other designs by just changing the power supply connected.

    Thank you for the suggestion. But can I ask if I can use TPS25740/A since they also have 5V only options?

    Thank you!

    Edgar

    EDIT: I asked for TPS25740A since I want to also provide 900mA in case the device is not asking for 3A. Thank you!

    EDIT 2: I can use TPS2514A for TPS25810 to support lower than 3A. So the question for the TPS25740 and TPS25740A is the one remaining.

  • 0 in reply to Edgar Laurrence Osis
    Prodigy 170 points
    Also, if I want to use USB-PD protocol, can I use TPS25810? Because as I've read, it is only for DFP, not for USB PD. Thank you!
  • 0 in reply to Edgar Laurrence Osis
    TI__Mastermind 27605 points

    Hello Edgar,

    Yes, you can use the TPS25740 or TPS25740A following the tables below.

    However, I would not recommend using either of these devices as we are discontinuing our support for them, and are manufacturing/supporting them only for existing customers and designs. The device we recommend in its place is the TPS65987D.

    If you are wanting to only advertise 5V/3A, then the TPS25810 is the correct part to use. You are correct in that it cannot support USB-PD protocol, but if you are only supporting 5V and no alternate modes, then their is not need for a PD controller.

    Hope this answers your question. If so, please click THIS RESOLVED MY ISSUE

  • 0 in reply to Adam Mc Gaffin
    Prodigy 170 points
    Thank you for the help!