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LM3478MA - low frequency ripple at low load

Oleg Migal
Prodigy 10 points

Good day, 

I'm designing a dc-dc boost converter, where Vin=12V, Vout=30V, I(load)=0...0.3 Amp. When I(load) decrease less then 0.02 Amp, I have a low frequency ripple in Vout. f (ripple)=50Hz at I(load)=0.02 Amp and 12.5Hz at 0.01Amp. How to improve the operation of the converter at low load?

Thanks. 

  • 0
    Prodigy 150 points

    Hello,

    I am having a similar issue and was wondering if there is any further information about this.

    In my case, if I run the switcher at light load (180mA) (3.7V in, 12V out) at 1MHz, I see about 488mV pk-pk of 51 Hz noise.  If I lower the switching frequency to 806kHz (or lower), this 51 Hz noise goes away and all I see is low level high freq. noise.  This part is in an audio application and the 51Hz is affecting my SNR.

    Could you please give me some guidance on this problem?  Thanks very much,

    Regards,

    Dave