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TPS54821: Output inductor temperature very hot ?

PYTsai
Genius 11495 points
Part Number: TPS54821

Hi 

We are using it for LED Driver power with Vin=12 V, Vout=6 V, Iout=3.84A. We following the Webech result to build the PCB. However see a problem the inductor temperature is very hot. Our schematics as below, can you help review if anything wrong?

  • 0
    TI__Mastermind 18510 points

    Hi, what's the temperature data? do you have spec of the inductor you are using?

    Yuchang

  • 0 in reply to Yuchang Zhang
    Prodigy 10 points

    Hi  Yuchang

    I don't know temperature. Just know don't touch the inductor for a long time. It's very hot.

    This image is inductor spec.

    SJ

  • 0 in reply to user6164888
    TI__Mastermind 18510 points

    SJ, As you said if just can't touch it for a long time, that should be not very hot, usually if the temperature at over 50C, we cannot touch it for a long time, if higher to 70C, we only can touch it for a short time. so I suppose the inductor should be not very hot. suggest you test it with tool to get the real temperature for evaluation. and if it is real hot, change a lower DCR inductor instead.

    Yuchang

  • 0 in reply to Yuchang Zhang
    Prodigy 60 points

    Hi Yuchang,

    Thank you for your reply.

    I am an SJ partner,

    But something I can’t understand. I want to discuss with you again.

    can’t touch it for a long time => mean ： Inductor is very hot

    can touch it for a long time => mean ： Inductor isn't very hot

    -------------------------------------------------------------------------------------------------

    As you suggest, I choose lower DCR resistance value to improve efficiency and reduce power consumption.

    Thermal energy is also reduced compared to previous designs. (I see..)

    1. I'm looking for lower DCR samples.

    2. From TPS54821 design, Whether to adjust the compensation value or any way for further analysis.

    Thanks

  • 0 in reply to Tim HM
    TI__Mastermind 18510 points

    can’t touch it for a long time => mean ： Inductor is very hot

    can touch it for a long time => mean ： Inductor isn't very hot

    Yes, above is what i mean, and so I suggest you to test the temperature to confirm it.

    For the circuit compensation, so far looks fine, let's keep this first, and based on transient test result to determine whether need to fine tune.

    Yuchang

  • 0 in reply to Yuchang Zhang
    Prodigy 60 points

    Hi Yuchang,

    Update temperature measurement data

    Burn-in time = 10 minutes
    Ambient temperature = 22 ℃
    Iout = 3.94A
    TI TPS54821 = 82 ℃
    Inductor VCMT063T-3R3MN5T (Cyntec) = 69 ℃

    The temperature is very high, and the driver is still working.
    Maybe increase layout trace width of ground, improve heat dissipation
    or any suggestions for this heat problem.

    Thanks

  • 0 in reply to Tim HM
    TI__Mastermind 18510 points

    Can this result be accepted by your system? generally this result is not very high for most system.

    but from simulation, IC temperature only around 56C, so there should be some gap for layout improvement, suggest you can enlarge thermal pad plane, GND plane and Vin pin plane to improve it. also add some vias for thermal pad and GND for multi layers dissipation.

    For inductor, you can select smaller DCR inductor to improve.

    Yuchang

  • 0 in reply to Yuchang Zhang
    TI__Mastermind 18510 points

    Hello, Seems there is no more questions feedback from you, this thread will be closed first, you can re-open it if needed.

    Yuchang