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Original question:

LM4940: Input specs not clear from the data sheet?

LM4940: Can the rear pad/tab be connected to GND?

Emanuele Ronchi
Prodigy 20 points
Part Number: LM4940

Hi I need to use LM4940 in my PCB but I don't understand if I can the pad/tab (pin 10) be connected to GND?

The datasheet wasn't too clear on this, it only mentions to solder this to a large enough copper area.

Please let me know asap

Thanks!

  • 0
    TI__Guru** 103365 points

    Hi Emanuele,

    The pad in the back of the devices usually have some connection to GND, I'm getting some samples to double check the continuity. I should get some data by end of week or early next week, I'll let you know as soon as I get the samples.

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • 0 in reply to Ivan Salazar
    Prodigy 20 points

    Thanks Ivan, any chance you can let me know *something* today or tomorrow because I absolutely need to complete the board asap and I'm already late. My strong preference is to connect the pad to GND because allocating a large copper area just for heatsink and nothing else would waste a huge amount of space on the board. 
    Thanks!

  • 0 in reply to Emanuele Ronchi
    TI__Guru** 103365 points

    Hi Emanuele,

    I'm almost certain the pad can be shorted to GND, this is a single-supply device, if it would be dual supply I would have more doubts on it.
    I only want to verify this on the actual device because the layout from data sheet suggest GND pins are connected directly to the header pin instead of doing it through the copper plane.
    Unfortunately I'm not able to identify any previous data on this matter for this specific device.

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • +1 in reply to Ivan Salazar
    TI__Guru** 103365 points

    Hi Emanuele,

    I just got the units and EVM and tested for continuity. I can confirm GND pins are internally connected to the pad on the back of the device.

    Best regards,
    -Ivan Salazar
    Applications Engineer

  • 0 in reply to Ivan Salazar
    Prodigy 20 points

    Thanks a lot Ivan!