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LM2586: Large pad on KTW TO-263 DDPAK

Darren Jenkins
Genius 11466 points
Part Number: LM2586

LM2586 team,

Can you confirm if the large pad on the TO-263 package is connected to Ground internally?  I see this is labelled on the TO-220 package in the datasheet (page 3, section 5), but not on the TO-263 KTW DDPAK.

If not, how should the customer connect it on their schematic?

Thanks,
Darren

  • 0
    TI__Mastermind 23400 points

    Hi Darren,

    Sorry to keep you waiting for so long.

    Looking at the pin configuration in the datasheet, there should be no internal connection between the the Ground pin 4 and the power pad on the bottom of the device, neither for the T0-220 nor the TO-263 package.
    I do not assume the 'GND' and 'Ground' description on the mentioned image of the TO-220 can be understood as the same pin.

    To make sure the design functions as intended, the common approach regarding the layout is to make a small, external connection between the power ground and the signal ground (Meaning the GND layer and Ground pin 4). This way, the customer can make sure the two grounds do not shift apart while still reducing the noise on the feedback signal.

    Please let me know if you have additional questions.

    Best regards,
    Niklas

  • 0 in reply to Niklas Schwarz
    TI__Genius 11466 points

    Hi Niklas,

    Thank you for getting back to me. I should have worded my question differently. Should the large pad on the TO-263 be connected to the ground plane on the PCB?

    Thanks,

    Darren

  • +1 in reply to Darren Jenkins
    TI__Mastermind 23400 points

    Hi Darren,

    thanks for the clarification.
    Generally, I can always recommend to connect the power pad to the ground layer of the PCB.
    The power pad is meant to move away the dissipated heat from the IC. If the pad is connected to a large ground layer, the produced heat can flow away from the IC much easier and the danger from overheat and thermal shutdown is strongly reduced.

    I hope this explanation is helpful.

    Best regards,
    Niklas

  • 0 in reply to Niklas Schwarz
    TI__Genius 11466 points

    Yes, thank you Niklas.

    Darren