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PMP40871: Line regulation

Hideki Hayashi1
Expert 8650 points
Part Number: PMP40871
Other Parts Discussed in Thread: TPS61391

Hi team,

How is the load regulation at >25mA? Customer's phantom power is 28mA as max. And is there any side effect over 20mA?

Best regards,

Hayashi

  • 0
    TI__Intellectual 2885 points

    Hi Hayashi,

    Sorry for the slow response.  If the input voltage is 3.3V, the TPS61391 will not be able to supply 48V output at 28mA, because it will be limited by the peak current limit and DCM operation (see section 8.2.2.2 of the TPS61391 data sheet.)  If the input voltage is 5V, you can use a 5.6uH inductor to keep the peak inductor current below the 800mA limit and remain in DCM with a 48V/28mA output.

    thanks,

    Brian

  • 0 in reply to Brian King
    TI__Expert 8650 points

    Hi Brian,

    I understand there is limitation when input voltage is 3.3V. But when I look the attached figure, there are voltage drop above 22.5mA. Will these be linear decrease above 25mA?

    Regards,

    Hayashi

  • 0
    TI__Intellectual 2885 points

    Hi Hayashi,

    It won't really be linear, but the output voltage will continue to decrease. It will behave more like a constant power limit, since the input current is limited by the peak current limit and the input voltage is fixed.

    thanks,
    Brian