• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 62 subscribers
  • Views 4610 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

Short Circuit Protection with SEPIC DC-DC Converter Topology

DC DC converter short circuit handling

Nadhem JEMLI
Prodigy 45 points
Other Parts Discussed in Thread: TPS61088, TPS92692-Q1

Hello,

I'm a beginner in the world of power supplies.I have watched a training video on your website about DC/DC converters topologies, pros and cons.

I want to know how the boost converter Handle input short circuit and the buck converter handle the output short circuit.

Thank you by advance.

  • 0
    Prodigy 5 points

    Hello Nadhem, thank you for joining the Forum.

    The Boost can not support an output short.

    The Buck can not support an input short.

    As an example for the boost question, please see this design example.

    This reference design delivers an output short-circuit

    protection solution for the TPS61088 boost converter.

    This feature is realized by an over current protection

    (OCP) circuit. When the output is shorted to ground or

    the load current is higher than a certain value, the

    OCP circuit will disconnect the TPS61088 from the

    load. This solution just requires an additional low-cost

    comparator, a sense resistor, and a small sized NMOSFET. With this small amount of additional

    circuitry, the TPS61088 is protected from being

    damaged in the output short circuit and over load

    conditions.

    Basically you have a straight path from VIN to VOUT through the boost diode, when Vout is shorted.

    For the buck the issue is similar but in the other direction.

    The body diode of the high side mosfet will conduct from Vout to VIn, if Vin is shorted.

    This picture shows the intrinsic body diode of a mosfet.

    Does this help your understanding?

  • 0 in reply to Ed Walker
    Prodigy 45 points

    Dear Mr WALKER,

    Thank you for your response.It is very Helpful.I think to avoid the problem of Short circuit, i can use two serie converters. Boost then Buck.In fact i'm trying to design an automotive Led driver and i should make attetion to input and output short circuit.So using a Boost Voltage regulator then a Buck current regulator is a good solution.Do you agree Mr WALKER?

    Best Regards,

    Nadhem

  • 0 in reply to Nadhem JEMLI
    Prodigy 5 points

    Hello Nadhem,

    There are better ways to address protection than using 2 stages.
    You need a boost topology that has output short protection.

    Please see the TPS92692-Q1 
    http://www.ti.com/lit/ds/symlink/tps92692-q1.pdf

    This contains a circuit which drives a mosfet on Vout Iout to the leds.
    The mosfet will open if a short or other overload is detected, therefore mitigating the boost output short problem.

    This solution is much lower cost that using 2 converter stages.