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TPS40061 damaged

volkan serter
Prodigy 80 points
Other Parts Discussed in Thread: TPS40061

Hi,

 

I am using TPS40061 as indicated in slvr235.pdf and see that it is burned frequently . Has anybody meet such kind of burning or problems?

I give the rated values.

  • 0
    TI__Guru 56785 points

    Volkan,

     

    Why the IC is burrning up isn't always an easy subject, but here are some things to look into:

     

    1) IC power dissipation

      The TPS40061 controller's two linear regulators (Outputs BP10 and BPN10) dissipate power in the IC.  This power dissipation is equal to the gate charge of the powered MOSFET times the switching frequency times the input voltage (48V).  Check the switching frequency, MOSFET gate charge and input voltage.  Compare this power dissipation with the IC's power handling capabilities.

    If the PowerPad is soldered to the PCB ground plane, the IC can handle 1 - 1.5W at room temperature.

    If the PowerPad is not soldered to the PCB or is not connected to a wide ground plane, the IC's power handling capabiltiies might only be 500mW at room temperature.

    At elevated temperatures, these numbers are further reduced.

    2) VDD voltage Withholdings

    If the VDD voltage of the TPS40061 is exceeding the absolute maximum voltage (60V) even briefly, internal protection devices might clamp and the VDD voltage may need to drop well below 60V for the protection clamp to release.

  • 0 in reply to Peter James Miller
    Prodigy 80 points

    I checked the board and verified that powerpad is soldered correctly. Switching frequency 236 KHz. And I calculated the worst case power dissapation, which is equal to 700 mW.From this value I calculated the maximum ambient temp. and found it to be 57C. I set the ambient temp. to 50C and let the circuit run for 12 hours. Nothing happenned. IC works well. By the way, when the IC is damaged, high side and low side mosfets are also damaged. But there are cases which only the IC is damaged.

    High Voltage value may cause the damage, so I gave 65 volts to the IC and IC still works. After 70 volts IC is damaged permanently.

    In my case, I could not detect voltage rising above 48 V. Can you suggest any other point?

    Thanks