BQ24610: circuit cannot pass EMC RE test CISPR22 class B

user5831319

Part Number: BQ24610

schematic and pcb layout are below,i have test some method to modify the emc,but it still cannot pass.

please help me analyse where the question is,and what can i do to make it pass the test .thanks

0 user5831319 over 4 years ago

PCB format allegro 17.2,schematic orcad 17.2

0 user5831319 over 4 years ago

frequency is 100~300MHz,especially about 200MHz

0 Kedar Manishankar over 4 years ago in reply to user5831319

Hi,

Can you add 2x0.1uF 0603 or 0805 ceramic capacitors at the terminal where your input adapter connects to your board?
- Try this first as from your brief description, I believe this will help most mitigate the 180MHz band.
Do you have the horizontal and vertical antenna orientation data where the board is failing CISPR22-B?
What input source are you using?
Can you add a snubber circuit in parallel to the low side switching FET?
- To size the snubber, observe the frequency of ripple on the rising and falling edges of the PH node. Size capacitor value such that the frequency of ripple on the rising and falling edges of the PH node is halved. Then re-test for EMI as well.
Desolder all test points if you have any as these can act like antennas

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