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LM3424: LM3424

Guangyan Liu
Intellectual 2130 points
Part Number: LM3424

Dear Expert ,

Good day!

Our customer  use LM3424 in their application , 24V input / 24V 4A output , here is the schematic

When the load current larger than 3.5A , the inductor and mosfet will become hot , the customer test the inductor and FET gate wave , it become worse

Inductor

FET

at the same time the Inductance scream,  I try to let the customer use the larger inductor , 33u/10A->47u /10A，  the FET burn in one minute after power up  .

Could you help me to confirm the schematic and provide any suggestions ?

The FET (max parameter )

VDS =100V

Vgs=+/- 20V

Id=40A

BR,

Leon.liu

  • 0
    TI__Intellectual 1675 points

    Hello Leon,

    Due to the American holiday, E2E responses will likely be delayed. We will get back to you about this on Monday, September 29. Thank you for your patience!

    Best Regards,

    Caroline

  • 0 in reply to Caroline Fuschino
    TI__Mastermind 18890 points

    Hello Leon,

    I noticed that there is no decoupling cap (2.2uF) on VCC.  Did the customer did the calculations for for the design?  If they did please attach that for us.  

    In general, with high power/current that they are trying to deliver to the LED the FET has to be able to handle the heat being dissipated on it.  Layout is also of consideration since you have high peak current along with high heat that has to be remove from the power stage.  For 100W output and 80% efficiency you will will have 20W that you have to remove from the power stage.  You might need larger FET or parallel FET's for this high power level.  

    Thanks Tuan