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TLVH431B: Power dissipation

rahul ravi
Prodigy 80 points
Part Number: TLVH431B
Other Parts Discussed in Thread: TL431

I am looking for an electrical way to estimate the power dissipation. Is there an electrical way to do this? I can then use the calculated power dissipation to then estimate the actual temperature rise and a junction temperature. Also what is the RATED power dissipation for this device?

  • 0
    TI__Mastermind 19370 points

    Hi Rahul,

    Can you explain what you mean by electrical way?

    The most common way to calculate power dissipation is by finding the power going through the device. This will be the P = VI where V = VKA and I = IKA.

    The power dissipation will increase the Tj. By using Tj = Ta + RθJA*P

    Keep Tj below the ABS max Tj of 150C.

    You can read more about thermal dissipation in the app notes below.

  • 0 in reply to Marcoo Z
    Prodigy 80 points

    What I meant was using electrical equations and NOT using the junction and ambient temperatures.

    What do VKA and IKA stand for?

  • 0 in reply to rahul ravi
    TI__Mastermind 19370 points

    Hi Rahul,

    This Is still a but confusing to me. Either you work from Tj to get to the power dissipation or you work backwards from a measured value. Do you have a thermal probe or measurement device you can use? Or something that can measure the temperature at or around the TL431?

    There is no curve for the TL431 temperature drift to work backwards from. I can't say that if you measure "x" V it means the device is "y" hot.

  • 0 in reply to Marcoo Z
    Prodigy 80 points

    I would like to know how to calculate the power dissipation so that I may then use it to calculate a junction temperature. 

    What I am looking for is something like: Pdiss=VCC*ICC or like Pdiss=Pin-Pout 

  • 0 in reply to rahul ravi
    TI__Mastermind 19370 points

    Hi Rahul,

    I think there was a misunderstanding. I believe I provided the equations in the 2nd post.

    Looking at your equations "power dissipation" will just be P = VKA * IKA.

    Where VKA = output voltage

    Ika = current through the device.