LMR14020-Q1: EMI issue "9K Peak appears on the audio output"

Kygo Cheng

Part Number: LMR14020-Q1
Other Parts Discussed in Thread: TPS54340, LMR14020

Hi Team,

Now have LMR14020-Q1 EMI issue!

Due to the shortage of materials, the customer replaced TPS54340 with LMR14020 (PIN to PIN),
Sent ITU-T certification and was informed that EMI had 9K Peak.
It is confirmed by cross-comparison that it was caused by replacing it with LMR14020. What is the cause of this problem? There are ways to solve it, thank you!

over 3 years ago

+1 iAlejandro over 3 years ago

TI__Expert 8130 points

Hello Kygo,

I've never seen a conducted EMI result in such low-frequency ranges.. Usually, conducted EMI tests are within the AM band of 100kHz to 30MHz. This peak is way below the AM band. Are the conducted tests failing?

Regardless, multiple speculations:

There might be some internal difference between the devices
Placing an Input EMI filter can always take care of this. See the following App Notes: SNVA489, SNVA886, SNVA755.
I would of suggested to place some high-frequency cap, but the peak we are trying to take care of is at such low frequencies.

Regards,
Alejandro

0 Kygo Cheng over 3 years ago in reply to iAlejandro

TI__Expert 6830 points

Hi Alejandro,

Thank you so much for your help & feedback !

I will discuss this case closely with Customer,THX

0 iAlejandro over 3 years ago in reply to Kygo Cheng

TI__Expert 8130 points

Anytime. We are here to help.

Kind regards,
Alejandro

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LMR14020-Q1: EMI issue "9K Peak appears on the audio output"