LM3481: LM3481 current spike when mosfet turn on

Yangbo

Part Number: LM3481

Hi Team,

My customer is evaluating the LM3481 flyback demo, below is the schematic:

They saw a huge current spike when the mosfet turn. Can you help to understand the root cause of this sspike and how to kill it?

Thanks a lot!

Yangbo

over 7 years ago

0 Youhao Xi over 7 years ago

TI__Guru* 79145 points

This is normal and well known as the leading edge current spike. It is mainly caused by the reverse recovery of the secondary rectifier,as well as the gate drive current pulse.

0 Yangbo over 7 years ago in reply to Youhao Xi

TI__Intellectual 1690 points

Hi Youhao,

Thanks for your prompt reply.

This spike will result in the EMI problem. Do you know how to reduce the spike?

Thanks a lot!

Yangbo

0 Youhao Xi over 7 years ago in reply to Yangbo

TI__Guru* 79145 points

You need to slow down the gate drive speed by increase the gate resistor.

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LM3481: LM3481 current spike when mosfet turn on