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LM3205 in WSON package - thermal pad connection?

Peter Rush
Prodigy 20 points
Other Parts Discussed in Thread: LM3205

I am planning on using the LM3205 in a WSON package.

The datasheet doesn't seem to give any indication of what signal the thermal pad should be connected to. Should I connect this pad to PGND?

  • 0
    TI__Intellectual 1070 points

    Hi Peter

     I would follow the typical PCB layout example as shown in the datasheet which does not show the thermal pad connected to PGND.

     

    See pg # 18 of the Datasheet for a detailed layout description

     

    Thansk
    Chintan

  • 0 in reply to Chintan Parekh
    Prodigy 20 points

    Hi Chintan,

    Thanks for your response.  I saw the example layout on page 18 of the datasheet, but I am concerned that the size of copper area shown under the device will not dissipate much heat. 

    In the notes at the bottom of page 3 of the datasheet it states:

    "In applications where high maximum power dissipation exits (high VIN , high IOUT ), special care must be paid to thermal dissipation areas. For more information on these topics for WSON, refer to Application Note 1187: Leadless Leadframe Package (LLP) (SNOA401) and the Power Efficiency and Power Dissipation section of this datasheet"

    The Application Note indicates that thermal vias should be used to conduct heat from the exposed pad to the ground plane, however this is obviously only possible if the pad can be connected to ground.  If the pad cannot be connected to ground then I would need a large area of unconnected copper in my PCB simply to dissipate heat, which is not desirable.

    The "Power Efficiency and Power Dissipation" section of the datasheet seems to be missing!

    Is there any way of finding out what the pad is connected to inside the device?

    Regards,

    Peter