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LM5020: Need suggestion on Schematic

Rajesh Gupta
Intellectual 300 points
Other Parts Discussed in Thread: LM5020

Dear community,

We are designing a circuit for Input:-48V and output: 12V/3A. Attached is the schematic we are using, we are facing the problem that the input current is very high and there is damage of the output diode, mosfet, device(LM5020) and current sense resistor.

Please help for the suitable changes in the circuit. 

Best regards

Rajesh Guptae2e.docx

  • 0
    TI__Mastermind 25570 points
    I'd suggest increasing the soft start capacitor significantly. The 10nF currently on the pin will give a SS interval of about 1.25ms - try increasing it by a factor of 10. The increased SS interval will give the system more time to charge up the output capacitors and the currents will be lower too.

    I'd also look at the current in the transformer/choke, T1 in your schematic. Check that it is not saturating during the start-up.

    Regards
    Colin Gillmor
  • 0 in reply to Colin Gillmor
    Intellectual 300 points

    Dear Colin,

    Checked by increasing the SS Capacitor but the problem didn't resolve. Would request to advise on the transformer design if it is ok or not?

    Thanks & regards

    Rajesh Gupta