TEA19161 unstable at 90Vac input

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TEA19161 unstable at 90Vac input

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davelove
Contributor I

Why is TEA19161 PFC voltage unstable with 90Vac input?

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4 Replies

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Willy1
Contributor I

Hi NXP,

We use TEA19162+TEA19161 as a 165W adaptor design, now we encounter an issue related SNSFB disturbance.

When we power up circuit at 90Vac and 7.5A output load, the SNSFB and LLC_Vo is good, but after few seconds the waveform of Vo_LLC and SNSFB have 100Hz ripple voltage on these waveforms.

This disturbance is from PFC drain or HB_LLC power trace to influence SNSFB pin due to capacitive coupling I though.

But I check all your application notes AN11801, AN12330 and AN13140, they said poor TL431 design may lead mains 100Hz or 120Hz to the LLC output voltage.

Could you explain it in detail, I'd like to know the operational principle why 100Hz/120Hz lead to LLC output voltage with poor TL431 design.

Please See AN11801 section 13.3 TL431 circuit must be compact

Thank you very much.

e-mail: a0935693433@gmail.com

Willy Su

 

 

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596 Views
guoweisun
NXP TechSupport
NXP TechSupport

Hi,

You can check your schematic according attached calculation sheet.

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596 Views
davelove
Contributor I

Thanks GW,

By the way, I meant to type 19162, not 19161. The 90Vac instability has been identified as:

SNSMAINS pin magnetic field susceptibility from integrated LLC xfmr magnetic field leakage.

Must use NM (not mounted) SNSMAINS cap, to prevent instability.

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596 Views
guoweisun
NXP TechSupport
NXP TechSupport

Hi

I also suggest you read AN11801 page116 for the PCB layout of SNSMAINS pin.

Thanks!

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