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LM3150: Bootstrap capacitor

Guru 16770 points
Part Number: LM3150

Hi

The Cboot of LM3150 is recommended as 0.33uF to 0.47uF.

1.

What is impact for operation if larger capacitance value than recommendation is?

2.

What is impact for operation if smaller capacitance value than recommendation is?

BestRegards

  • 1. Too large means it may take a few switching cycles to charge CBOOT to the steady-state value. This may affect startup operation but should not damage anything. It will also cost more and may take more space for the larger cap.

    2. Too small means the cap might not have enough energy to maintain the steady state voltage during switching cycles. This would reduce the effective gate voltage on the FET which would not turn on the FET as well which would lead to more power dissipation in the FET / worse efficiency overall.

    -Sam
  • Hi Samuel

    Thank you for your reply.
    It is helpful!

    BestRegards