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LM2575HV: LM2575HV low temperature issue

Part Number: LM2575HV

Hi

We have face a issue at low temperature

Channel 2- Inductance current.

Channel 3- SW Switching waveform.

1. 25℃ Testing:   Load >300mA.  Switching is stable.   


2. -40℃ Testing:   Load >300mA.  Switching is unstable. When we increase Input voltage to 30V,  There has big/small duty change rapidly and result in bigger output ripple wave.   

But this made me confused , Usually at light load, there maybe has Big/Small duty change rapidly . But why increase Input voltage and at low temperature there also happen it.  

3. 65℃ Testing:   Load >300mA.  Switching is stable.

So, this maybe Cap result in because of Cap at  low temperature ?

What result in diffrent duty and frequency