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LMR33630: Can we make LMR33630ADDAR thermal pad floating ?

Masaharu Takahashi
Expert 4170 points
Part Number: LMR33630

Hi, Team.

This is MASA.

could you tell me below?

1.is it ok if Customer doesnt use thermal pad for working properly ?

-> Customer doesnt want to use thermalpad since it would be hard to replace easily.

so even the thermal pad is not soldered , Will IC work properly?

  • 0
    TI__Mastermind 25590 points

    Takahashi-san,

    The pin description of the datasheet states, "For the HSOIC package, the pad on the bottom of the device serves as both the AGND connection and a thermal connection to the heat sink ground plane. This pad must be soldered to a ground plane to achieve good electrical and thermal performance."

    The LMR33630 will get very hot if you try to draw lots of power and do not have the thermal pad connected to a ground plane. If they are not drawing lots of power, they can achieve good electrical performance and easy solderability by placing a small connection from the thermal pad to PGND.

    -Sam

  • 0 in reply to Samuel Jaffe
    TI__Expert 4170 points

    Hi, Samuel-san.

    So, it can be non soldering but worse thermal and electrical performance. right ?

    it depends on how much thermal IC dissipates , correct ?

  • 0 in reply to Masaharu Takahashi
    TI__Mastermind 25590 points

    Masaharu-san,

    Yes, using the thermal pad give better thermal performance. Not using the thermal pad gives worse thermal performance.

    But if the IC does not dissipate much heat (not much output power) then the thermal pad may not be necessary.

    -Sam

  • 0 in reply to Samuel Jaffe
    TI__Expert 4170 points

    Hi, Sam-san.

    according to Customer, the IC output will be collapsed if there is no soldering on thermal pad.

    this is different what you answer, can customer use IC without soldering on thermal pad really ?

    customer put input voltage up to 24V , the output voltage was collapsed(0V) with 0mA load condition without soldering on thermal pad.

    once they solder the thermal pad and they tried it again , IC will work correctly.(they replaced the IC with new one)

    could you confirm ?

  • 0 in reply to Masaharu Takahashi
    TI__Mastermind 25590 points

    Takahashi-san,

    Maybe I didn't explain clearly enough in my first post.

    The pin description of the datasheet states, "For the HSOIC package, the pad on the bottom of the device serves as both the AGND connection and a thermal connection to the heat sink ground plane. This pad must be soldered to a ground plane to achieve good electrical and thermal performance."

    This explains that they must connect the thermal pad to the ground plane (PGND) for proper operation. This is confirmed by the customer.

    The LMR33630 will get very hot if you try to draw lots of power and do not have the thermal pad connected to a ground plane. If they are not drawing lots of power, they can achieve good electrical performance and easy solderability by placing a small connection from the thermal pad to PGND.

    The small connection will connect AGND to the ground plane which allows the part to operate. Keeping the connection small ensures it is still easily solderable as requested by the customer.

    -Sam