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TPS2051C: Output Capacitance when using device side used and DRP

Part Number: TPS2051C
Other Parts Discussed in Thread: TUSB320

Dear Specialists,

My customer is considering TPS2051C and has a question.

I would be grateful if you could advise.

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(1) When using TPS2051C on the device side, is the output capacitance(150uF) necessary ?

I think it's not necessary.

(2) When using DRP, is it necessary to switch the connection of the capacitor by the switch?

Is it correct?

If so, could you please let me know the example modell of the switch or needed spec.

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I appreciate your great help in advance.

Best regards,

Shinichi

  • Hi Shinichi,
    1. As we discussed before, large output capacitors are required to meet the USB standard. If it doesn't need to meet the standard, large capacitors are not required.
    2. I'm sorry, I don't know what you mean by DRP, could you please help to explain it ? and then I will reply to your questions

    Best Regards,
    Kevin
  • Hi Kevin,

    Thank you for your reply.

    The customer'd like to confirm about.

    (1) When TPS2051C uses for Host, it has to provide outside and need a large capacitor.

    On the other hand, at device side , the power comes from the host,  output cap is not need 150uF.

    (2) The customer'd like to use USB typeC, it can deliver power both side, called DRP(Dual Role Port)

    According to the TUSB320 datasheet, it shows the example of DRP in I2C mode.

    Could you please see below.

    In this schematic, when UFP mode, output capacitance of BUS Switch is disconnected and no capacitance in the VIN pin side.

    UFP(Upstream Facing Port) means USB device side.

    The power comes from VOUT pin side and output to VIN pin side. 

    This seems output capacitance is not needed for device side and  the reason the customer asked.

    Could you please advise.

    I appreciate your great help.

    Best regards,

    Shinichi

  • Hi Shinichi,

    it is right that the device side doesn't need 120uf capacitance. we can see from the section 7.2.4.1 of USB 2.0 Specification, the restrictions are as below picture, hope it can help you.

    Kevin

  • Hi Kevin,

    Thank you for your reply.

    The output capacitance is depended on the USB2.0 Specification.

    I'll share your information with the customer.

    If the customer has an additional question, I consult you again.

    I appreciate your great help.

    Best regards,
    Shinichi