LM25141: LM25141 EMI problems

user5821856

Prodigy 60 points

Part Number: LM25141

We use LM25141 as inlet power encountered EMI problems

The schematic diagram is as follows:

We have filter before VIN_12A：

Conducted emissions from components – current probe method test fail.

At present, the following methods are considered:

We want to adjustment RHO,RHOL,RLO,RLOL,(R2103-R2108) , How to calculate the resistance value and maximum limit ?
Enable Spread Spectrum, DITHpin connect 0.01uF to GND.

And those methods？

We look forward to your reply

over 5 years ago

0 Daniel Li14 over 5 years ago

TI__Mastermind 27470 points

1. increase drive resistor will make the loss of mosfet larger, so you need balance the EMI and thermal. you can increase the drive resistor until the mosfet or efficiency become bottom neck.

2. Enable Dither will be helpful

some suggestion:

Puting more ceramic cap at input can reduce the ac ripple on the VIN_12VA, which may help. and you also need keep the loop of the input cermaic cap with Q2101 and Q2102 loop as small as possible
C2802 can paralleling with 0.1uFor smaller which has lower impedance in high frequency
reduce L2801 see any help
use Shield inductor

Thanks

0 user5821856 over 5 years ago in reply to Daniel Li14

Prodigy 60 points

Thank you for your reply. I think it's very helpful.

0 Daniel Li14 over 5 years ago in reply to user5821856

TI__Mastermind 27470 points

I will close this question, you can reopen it if you have further question.

Thanks

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LM25141: LM25141 EMI problems