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LM3481: lm3481

MAHENDER SHARMA
Prodigy 30 points
Part Number: LM3481
Other Parts Discussed in Thread: LM5060

HI,

I am using LM3481 in a design,where input is 6-11V, and output is 13.5V,

but i am facing a issue when i testing it .short circuit protection is not working .when short circuit occur at is out ,its MOSFET  Q4 burn .please suggest how can i resolve this issue.

I have attached the circuit of this section.

  • 0
    TI__Mastermind 21720 points
    Hi Mahender,

    Thanks for reaching out with your question.

    A boost controller does not inherently have output short circuit protection. When the output is shorted the input voltage supply is shorted through the diode (D9). To work around this a device like the LM5060 can be added to the front end of the converter to disconnect the supply for the boost controller. The other option is to use a SEPIC topology which has inherent short circuit protection.

    Please let me know if you have any questions.

    Thanks,
    Garrett
  • 0 in reply to Garrett Roecker
    Prodigy 30 points
    Dear Garrett,
    Please suggest how to protect mosfet Q4 when there is short circuit condition. I understand we can not prevent short circuit in current scheme.
    As per link given below, we can limit the current. Please explain which current you are talking about. is it switching current through mosfet? if it can be controlled please guide us how can we do so. Practically the device is not limiting the current through mosfet resulting in blow-up of mosfet.

    e2e.ti.com/.../2658333
  • 0 in reply to MAHENDER SHARMA
    TI__Mastermind 21720 points
    Hello Mahender,

    The post refers to the peak switch current limit calculations and not on how to protect from short circuit current.

    As mentioned above one solution is to add a circuit breaker to the front end of the boost to protect from an output short. Another solution is to design a SEPIC converter that inherently protects the input supply during a short circuit condition on the output.

    Thanks,

    Garrett