TPS54260-Q1: Output 52V under EFT test

Beida Song

Part Number: TPS54260-Q1

Tool/software:

Hi Expert,

My customer found the output of TPS54260-Q1 is 52V, not 0V, under the EFT test. Though he try add some Caps or TVS, but these methods doesn't work.

The schematic, test input waveform and output waveform as below figures. And the switch frequency is 350KHz, the input EFT frequency is > 350kHz.

Can you help analysis the issue and give some advice?

0 Ryan 21 days ago

Hello Brody,

An engineer has been assigned. We will get back to you soon.

Thanks,

Ryan

0 Beida Song 21 days ago

Information update:

The EFT voltage waveform is ±2kV, 100kHz, generated from 2 probe. Tps54260-Q1 is not destroyed under this condition.
When oscillograph differential probes are not connected, spike waveforms can still be observed, as below left figure and right figure(detailed spike waveform).
The results did not improve when the PCB board was wrapped with copper foil.
The amplitude has been greatly reduced when the PCB is connected to the lab ground.

question update:

Any method to increase the spike waveform value and frequency without connected to lab ground?
How to improve measurement method and probe position to avoid the oscillograph coupling noise?

0 Nityanand Hegde 21 days ago in reply to Beida Song

Hi Brody,

I will get back to you in couple of days.

Thanks,

Nitya

0 Nityanand Hegde 18 days ago in reply to Nityanand Hegde

Hi Beida,

Does device is able to power on normally after the EFT test in second case?. The passing of the EFT depends mainly on the PCB layout and placement of the input caps, inductor etc.. It is recommended to follow the EFT guidelines for passing the test and regarding the improved measurement method; i suggest you to refer few below app notes available on the web.
1. ww1.microchip.com/.../00002587A.pdf
2. https://www.infineon.com/dgdl/Infineon-AN80994_Design_Considerations_for_Electrical_Fast_Transient_(EFT)_Immunity-ApplicationNotes-v09_00-EN.pdf?fileId=8ac78c8c7cdc391c017d072b38ea5000

Thanks,

Nitya

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