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TPS2068: Reverse Current Blocking

Alen Barisic
Intellectual 1300 points
Part Number: TPS2068
Other Parts Discussed in Thread: TPS2051

Hello,

we need to modify the circuit below and thought to use 2x TPS2068 for that.

We use 2 USB ports

1x USB-C in device mode to the PC

1x USB-A in host mode for memory sticks

We want to remove the USB-A port and use the USB-C port for host / device.

• Device mode

The 5V USB from the PC goes to the LiIon Charger and supplies the whole system (up to 1.5A).

In the diagram below: Switch 1 = ON, Switch 2 = OFF. Is a default state if the uC has not yet booted.

• Host mode

The system is supplied by the LiIon battery, the system 5V comes from the boost converter, and this 5V is supposed to supply the stick in the USB-C port (blue line, currently USB-A switched by TPS2051). In the diagram below: Switch 1 = OFF, Switch 2 = ON. Switch 2 limited to approx. 600mA.

If we use 2x TPS2068 as,

Switch #1:

  • Vin to 5V USB, USB-C Port Site
  • EN# with Pull-down - Default on

Switch #2:

  • Vin auf System 5V
  • EN# with Pull-UP - Default off

Would that work in regard of „reverse current blocking“ without additional components?

 

Thanks,

Alen

  • 0
    TI__Expert 8420 points

    Hi,

    We will feedback you soon

  • 0
    TI__Mastermind 18031 points

    Hi Alen,

    The datasheet only indicates reverse current blocking function.

    But not sure the function works as on or off status.

    Need to have a test of this.

    Want to confirm that, you don't want S1 to turn off as reverse current charging, correct?

    For TI's policy, I will first click resolved button.

    If you have any other concern, contact me any time.

    If you think resolved, please help click 'Issue is solved button'.

    Thanks.

  • 0 in reply to Ziv Zhang
    TI__Intellectual 1300 points

    Hi Michael, Ziv,

    would be great if you could check that on the bench. Thank you.

    it will be only for the OFF status.

    When our device works as DEVICE, it is connected via USB-C to a PC or USB Charger, S1 will be ON and S2 OFF. There will be a 5V voltage on the output of S2, as well on its input, but they can be slightly different.

    When we switch the USB-C port to HOST mode, then we open S1 and may close S2. S1 will have 0V (S2 open) or 5V (S2 close) on its input, while having between 3.4V to 4.2V on its output (LiIon cell voltage).

    In fact this is a very close application to an Laptop USB-C port with both direction charging function.

    Regards,

    Alen

  • 0 in reply to Alen Barisic
    TI__Mastermind 18031 points

    Hi Alen,

    Have a test on EVM boards.

    The part only has the reverse current blocking function as IC is disabled.

    As IC is enabled, don't have the reverse current blocking function.

    For TI's policy, I will first click resolved button.

    If you have any other concern, contact me any time.

    If you think resolved, please help click 'Issue is solved button'.

    Thanks.