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TPS2121 Multiple controller to one battery charger via power mux

Cristian Gantner
Prodigy 10 points
Part Number: TPS25751
Other Parts Discussed in Thread: TPS2121, BQ25713,

Tool/software:

Hello,

We currently develop a product that has 3 usb-c gen 3.2 ports, sink only, and each of those can charge the battery. For this i need to the the PPHV(15V max) outputs together, so that it does not matter in which the USB-C cable is plugged.

1. Can i tie them together or should i separate them with a diode? 

After the PD controllers we use a TPS2121 to mux the USB voltage with an output form an POE DC-DC controller(12V max). The output voltage of the TPS2121 goes to an BQ25713 battery charger IC where it provides system voltage and charges the 2S battery.

2. Does the TPS25751 need direct connection to the BQ25713?

3. Do you have a part like TPS2121 that has 3 inputs and one output and supports USB-C PD voltages?

Thank you.

  • 0
    TI__Mastermind 34676 points

    Hi Cristian, 

    Cristian Gantner said:
    We currently develop a product that has 3 usb-c gen 3.2 ports, sink only, and each of those can charge the battery. For this i need to the the PPHV(15V max) outputs together, so that it does not matter in which the USB-C cable is plugged.

    Do you have a block diagram of what your full-system would look like? Also with three USB-C port, does your system have an MCU for port power management? 

    Cristian Gantner said:
    1. Can i tie them together or should i separate them with a diode? 

     Ideally you would need to include diode to prevent back-feeding from one USB-C port to another. 

    Cristian Gantner said:
    2. Does the TPS25751 need direct connection to the BQ25713?

    Can you elaborate on what kind of connection are you referring to? TPS25751 does have integrated I2C control for BQ25713 however that is intended for single-port design (one PD controlling one BQ). Since your application has multiple Type-C port (and multiple PD controllers) you will not be able to use TPS25751 integrated I2C control for this application. 

    Cristian Gantner said:
    3. Do you have a part like TPS2121 that has 3 inputs and one output and supports USB-C PD voltages?

    I'll forward your thread to the power switch team for their input on TPS2121 alternatives. 

    Thanks and Regards,

    Raymond Lin

  • 0 in reply to Raymond Lin
    Prodigy 10 points

    Hi Raymond,

    I attached a diagram of the power tree.

    The diodes are currently missing. Each port is sink only and goes to the TPS2121 chip. The charger is set to not pull more amps than available.

    I mean the I2C connection. I would tie the BQ25713 to the main MCU, not to any of the three TPS25751.

    What do you mean with "MCU for power management"? Do you have an example of one?

    Thank you for forwarding.

  • 0 in reply to Cristian Gantner
    TI__Guru* 79181 points

    Hi Cristian,

    We do not have a part with 3 inputs.

    Regards

    Kunal Goel