• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 63 subscribers
  • Views 327 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.

Power loss in controller IC LM3481

Devendra Patel
Prodigy 50 points
Other Parts Discussed in Thread: LM3481

I need to find out feasibilty of LM3481. For this I want power loss in IC.

Can I get power loss number and juction temprature at 125C ambient for following driving condition.

Vin=9 to 32 V.

Fsw=350KHz

LM3481 driving FET buk9616-75.

As per my calculation p_ic=Qg*Fsw*Vin

At vin=32V power loss is coming 0.47.

This power loss will give juction temp of 190C which will be far more than max. allowable junction temp.

  • 0
    TI__Genius 10115 points

    Hi Devendra,

    First off, if your ambient temperature will be 125C then according to the device datasheet you wil not be able to dissipate any power within the device without going over the recommended operating rating of the device.

    Second, your equation for power loss is very close to what you would see dissipated within the device.  You would also need to add quiescent current to the equation but the contribution from this is much less than the losses from the gate drive.  Based upon my back calculation of Fsw it looks like you want to run the device at 1MHz.  If you want to lower the power losses (temperature) within the controller and the rest of the power solution you should look at lowering the switching frequency.

     

    Regards,

    Marc