LTC3632 glitch when slowly increasing Vin

Hi.

Customer is using LTC3632, he made some tests.

LTC3632  powered  from LAB power supply, when increasing slowly input voltage  from 0 , converter trying to start up (oscillate) but can set adequate output voltage  and sets 0.8-1 V or Vfb below 0.8V.  After that converter don't  work  even if Vin  is 10-20 V.

When current limit increased glitch appears less frequently, maybe there is short curcuit protection glitch or internal circuits can't start properly near  border voltage;

It's not critical problem in application, but may cause failure.

I asked customer for  schematics.

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    •  Analog Employees 
    on Apr 29, 2021 9:08 AM in reply to Eugeny.Ivashenko

    Hi Eugeny,

    I agree with Willy to ask scope shots at Vin/Vsw/Vout as starting point. Its hard to know or explain what's going on without see these. At quick glance, I don't see anything amiss with the schematic.

    You are using RUN and HYST pin functions into a divider resistor setup. Make sure this setup is not interfering with the input voltage rising level.

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