LM3481: the part number is above

Tobias Kebis

Part Number: LM3481
Other Parts Discussed in Thread: CSD17303Q5

Tool/software:

The thread I want to comment to is locked, I hope this gets linked somehow.

I finally found a solution for the problem. It was the mosfet. When I tried it with the recommended CSD17303Q5, suddenly it works flawlessly. I could go above 8A and even abrupt start was not a problem. I wonder if the SMD package could have such an influence. I still didnt add gate resistor (although I added a footprint to have the possibility) and the rest of the circuitry is just as in TI bech recommendation.The only problem, that is there now is with EMC. The radiation is well above the limit for industrial appliacation.

3 months ago

0 Niklas Schwarz 3 months ago

TI__Mastermind 26930 points

Hi Tobias,

Happy new year and thanks for opening a new thread.
Could you comment with a link to the previous thread you are referring to?
It does not get linked automatically and it is difficult to find the thread through other means.

Thanks and best regards,
Niklas

0 Tobias Kebis 3 months ago in reply to Niklas Schwarz

Prodigy 20 points

Hi Niklas,

happy new year too!

thanks for the reply, here is the link

e2e.ti.com/.../5481550

0 Niklas Schwarz 3 months ago in reply to Tobias Kebis

TI__Mastermind 26930 points

Hi Tobias,

Thanks for adding the link.
I am glad to hear the new MOSFET solve a lot of the previous problems.
Regarding EMC, could you take a waveform of the SW voltage and zoom in until the rising and falling flanks are clearly visible?
If we see oscillation or strong overshoots, this might be the cause for the bad EMC performance.

To reduce ringing, you can consider increasing the gate resistance to slow down the switching flanks, or add an RC snubber across the MOSFET or across the diode.

Best regards,
Niklas

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LM3481: the part number is above