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LM2594: LM2594 / LM2594HV Protection Features: Current Limit and Thermal Shutdown

Part Number: LM2594
Other Parts Discussed in Thread: LM2596, LM2595

Dear Sir /Madam,

Would you mind elaborating more on the LM2594Protection Features such as Current Limit and Thermal Shutdown?

Does the device recover itself and continue normal operation after detecting such fault? Or does it require a power cycle to get back to normal?

Thank you  

-Arief

  • Hello

    Thank you for choosing TI as your component supplier of choice, and thank you for 

    reaching out to us with your questions regarding the LM2594 family of DC/DC converters.

    Let me try to answer your questions as best as I can.

    1.         The LM2594 has thermal shutdown, current limit and short circuit protection.

    2.         Unfortunately, we do not have data for the exact values of the TSD trip points.

        However, I would guess that they are in the region of shutdown at 150°C and

        recovery at 140°C.  The recovery is automatic and requires no power cycle, etc.

     

    3.         The current limit is cycle-by-cycle.  Once the inductor current hits the current limit, that switching

                cycle is terminated.  The next clock cycle will turn the power switch back on.  This is your typical

                cycle-by-cycle current limit operation that is common to many buck regulators; no power cycle, etc. is

                required.

     

    4.         The short circuit protection begins to operate at approximately 10% above the first current limit level,

                mentioned above.  With very heavy overloads, and/or short circuit on the output, the inductor current can

      exceed the first current limit threshold.  This can occur due to inductor saturation and/or delays in the

      current limit comparator.  If the inductor current reaches the +10% level, then the switching frequency

      will begin to fold back. This will help to give the inductor more time to release its stored energy and prevent

      inductor current run-away.  Once the overload is removed, the device will function normally; no power cycle, etc. is

                required.  This method is also commonly found in many DC/DC converters.

     

    5.         Of course, all of these protection methods cannot ensure that the device will be "bullet proof" against all types of abuse.

                However, they are most effective when the device is used within the recommendations and guidelines provided in the device

                data sheet and any pertinent app notes.

    6.          All of the above applies to the LM2595 and LM2596 family of devices as well.

    I hope that this has helped to answer your questions.  If I can help you with anything else, please do not hesitate

    to ask.

    Again, thank you for choosing TI,and have a nice day.

    Sincerely,

    Frank D

  • Hello Sir,


    Thank you for a very detailed answer on the protection features on LM2594.

    This will be a very useful information for all customer using the LM2594 / LM2594 HV

    Thank you

    -Arief