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TPS23753: an operation when power consumption is out of range

Part Number: TPS23753

Dear Specialists,

My customer is considering TPS23753 to the their system and has an inquiry.

I would be grateful if you could advise.

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We are currently considering to install in our products, we are making a study useing in Class 4 at the point of maximum power consumption.

 However, since the minimum power consumption is about 9 W, it does not match the PD Class 4 range (12.95 - 25.5 W) in the table above. If the power consumption deviates from the class 4 power range, what will happen? Please tell me about both cases where it falls below or exceeds the power range.

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I appreciate your great help in advance.

Best regards,
Shinichi

  • Hi Shinichi,

    If the PD falls below the Class 4 power range, the PSE will just supply less power. The class is an indicator of max expected power. The device does not have to operate in this range the whole time.

    For the case of the PD rises exceeding the power range: Since the PD has already communicated what power class its configured for, the PSE will limit the supplied power to maintain the amount of power budgeted for the PD.

    In the case of the TPS32880, the PSE will enter foldback current limiting (See section 2.2 of www.ti.com/.../snva736.pdf), while other PSEs may do simple current limiting while maintaining a voltage.

    The current limit of the PSE is lower than the current limit of the PD, so the PSE can maintain power budgeting & sense faults. The PD current limiting is more for quickly protecting the DC/DC circuit & PD controller from short circuit events.

    Thanks,
    Tom
  • Hi Tom,

    Thank you for your reply.

    I'll share your information with the customer.

    If he has an additional question, I cousult you again.

    I appreciate your great help.

    Best regards,
    Shinichi