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Original question:

TPS65987D: Questions regarding a TPS65987D design

TPS65987D: Working with both PD and non PD power supply

Nir Dvash1
Intellectual 470 points
Part Number: TPS65987D
Other Parts Discussed in Thread: TPS25750, TPS25750EVM,

I have a system which needs to charge a battery by either a PD power supply or a non PD power supply - the user may connect one kind or the other and I have no control over that.

The battery is charged using a TI charger IC.

I want to design my system so that in any case, power will be available to the charger IC and I was thinking of using this board but connect the VBUS pin DIRECTLY to the charger IC (which can handle 5 to 15 volts). I see two options here:

If a PD power supply is connected, the 65987 will negotiate a contract and the agreed power will be supplied on VBUS. If a non PD power supply is connected, the 65987 will negotiate nothing but in any case VBUS will have power (since any regular USB C power supply will power that pin)

Do you think this can work?

Nir

  • 0
    TI__Mastermind 30000 points

    Hello,

    Have you considered using a different PD controller such as the TPS25750? This device has built in charger control functionality to control a battery charger without need for additional programming. Can refer to the TPS25750EVM as well which uses a battery charger on the EVM itself

    As far as your design setup, I would not recommend connecting the input to the battery charger directly to VBUS. The USB spec only allows for a maximum capacitance of 10uF to be present on VBUS, so you will need some type of switch to isolate the capacitance needed for the battery charger. The TPS25750 or TPS65987D have this capability to isolate VBUS, and close their respective power path when a source device has been connected to the Type-C port

  • 0 in reply to Adam Mc Gaffin
    Intellectual 470 points

    Hello Adam

    Thank you for advice. I will check the TPS25750 solution you have suggested but still my question remains - what will happen if the user connectes a non PD power

    supply to our product?

    Nir.

  • 0 in reply to Nir Dvash1
    TI__Mastermind 30000 points

    Its the same as if a PD device has been connected. We will see that a charger has been connected based on the Rp on the CC pins, and close the power path accordingly. Your request of providing power to a charger regardless if the attached source is PD capable or not is a very reasonable/common one, the PD controller accounts for a non-PD source being connected as well