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LP8861-Q1 - without Power Line FET

Ryuji
Guru 20090 points
Other Parts Discussed in Thread: LP8861-Q1

Hello,

Our customer would like to remove the Power Line FET for reducing the parts number.
When they don't use Power Line FET, the power line is not isolated from the output.
Could you please let me know the concerning point on this usage?

Also the customer use LP8861-Q1 on the following conditions without Power line FET.
If there is any concern, please let me know.

Vin=8.7V, Vboost=22V, Iled=40mA x 4string =160mA, Fsw=2.2MHz
Cin=10uF cer. x 3pcs, Cout=10uF cer. x 3pcs


Best Regards,
Ryuji Asaka 

  • 0
    Guru 20090 points
    Hello team,

    I'm looking forward to the reply.

    Best Regards,
    Ryuji Asaka
  • 0
    TI__Intellectual 1235 points
    Hi Ryuji,

    As you know the Power-line FET is an optional feature that allows further protection in boost/SEPIC overcurrent state. The power-line FET is intended not only to protect device but also boost components, and LEDs in case of shorted Vboost and too-high Vin voltage. I understand your conditions are not extreme ones but keep in mind that power-line FET control also features soft-start which reduces the peak current from the power line during start-up. So as you see although it is a matter of choice I think that by removing the power line transistor you could potentially compromise or limit to some extent system performance unless you have other means to disconnect the input supply from the system in the event of a fault, reduce inrush current and standby power consumption.

    Kind Regards,
    David D Quintana