LM3481: the Csen choose of LM3481 Compensation Ramp

zhongyi chang

Prodigy 110 points

Part Number: LM3481

hi,

could you tell me how to choose the capacitor Csen?

over 7 years ago

0 Jasper Li over 7 years ago

TI__Mastermind 46905 points

the expert who support this IC will reply you when back to office

0 zhongyi chang over 7 years ago in reply to Jasper Li

Prodigy 110 points

Excuse me, are they back to help me solve this problem?

0 Youhao Xi over 7 years ago in reply to zhongyi chang

TI__Guru* 78060 points

We usually recommend an Rsl to be 100 to 1k, and Csen to be 1n to 100pF, namely Rsl x Csen = 0.1us, which will help filter out the leading edge current spike.

0 zhongyi chang over 7 years ago in reply to Youhao Xi

Prodigy 110 points

I confused about the 0.1us. This time depend on the switch frequency, or it is a fixed recommended values?

0 Youhao Xi over 7 years ago in reply to zhongyi chang

TI__Guru* 78060 points

Hi user5292892,

The rule is, the delay time should be long enough to filter our the leading edge current spike, but not too long to distort the main switch current waveform, especially the to slope. 100ns is a good start point for circuit switching in a few hundred kHz. If you go into MHz range, you should consider to reduce the delay time.

Hope this clarifies.

Thanks,
Youhao

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LM3481: the Csen choose of LM3481 Compensation Ramp