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LM5025A Application question check

Sulyn ZHANG
Expert 8700 points
Other Parts Discussed in Thread: LM5025A

Hi Team,

My customer is now using our LM5025A and these want to check following questions:

Above is customer's schematic. So can this start-up circuit works?

I can't the see the start-up current specific in our datasheet, is the start-up current is the summation of the "startup regulator leakage current" and "Vcc supply current Icc" followed?

Thanks a lot for you support!

 

Sulyn

  • 0
    TI__Expert 8700 points
    Team,
    I want to echo more information, input voltage is 380V and the VBIAS is from auxiliary winding.
    Your urgent support is appreciated, thanks very much!Sulyn
  • 0 in reply to Sulyn ZHANG
    Genius 3295 points

    I would check the following:

    D6 bias current - Is 380 uA high enough for it to be in the zener breakdown region? Also can it handle 100 mW of power?

    The Vin pin goes to another linear regulator with a pass transistor inside the IC. I would add a 450 V, 0.1, 1.0, or 10uF capacitor at this pin to make sure the voltage is stiff enough for the regulator inside the IC. Also I think the capacitor is needed for the UVLO and hysteresis.

    Can the MJExxx NPN xtor handle 0.392 W without burning up?

    If you are sure the components are biased correctly and they can dissipate the power they absorb, then this is a good design in my opinion. If it were my design I would verify it using TINA TI SPICED.