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LM5020: Max and Min current setting confirmation

Allen Lu
Intellectual 2510 points
Part Number: LM5020

Hi team;

 i would like to confirm with  you the Max and Min output current setting of this device.

 As this typical circuit , the sensing R8 and R9 are both 0.47Ohm, and the CS detect value is 0.5V, so i think the max current should be 0.5/0.235=2.127A?

 how comes as 4.5A Max Iout?

tks for your explanation.

 

  • 0
    TI__Mastermind 19625 points

    Hello Allen,

    Thanks for reaching out to us and sorry for the delay over the weekend.


    0.5V on the CS pin is the over-current protection level, so during regular operation this current would be even lower.

    As you can see in the schematic, there is no means of measuring the output current.
    The current measured by the sense resistor R8/R9 is the current through the primary winding of the transformer while the FET is turned on.

    As for every transformer, currents and voltages depend on the turns ratio.
    In this case you will find:  Prim : Sec = 1 : 0.23.

    So  the output current (secondary current of the transformer) is about four times higher than the primary current.

    Best regards,
    Harry
     

  • 0 in reply to Harry Hofner
    TI__Mastermind 19625 points

    Hello Allen,

    I have not heard back from you for a while.

    I assume your question has been answered, so I will close this thread now.
    If you still have questions you can re-open this thread or just start a new one.

    Thanks and regards,
    Harry