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UC1843A-SP: Application note or example layout for LCCC-20

Aki Jupic1
Prodigy 50 points
Part Number: UC1843A-SP

Hello,

I am looking for an app note or an example layout for the 20-pin UC1843A-SP LCCC package.

The circuit is driving a low-side NFET for an LED control application.

The biggest concern is the proper layout connections for the PWR GND and GND pins. Do you have any recommendations?

Thanks,

Aki

  • 0
    TI__Mastermind 21965 points

    Hey Aki,

    I don't have anything specific to the LCCC package for you, but I can comment on some guidelines.

    The GND pin will be for the analog circuitry and thus its important to isolate this ground from noise caused by switching when possible.

    The PWRGND can be a bit noisier since it will be for the outputs.

    I do suggest for PWRGND adding a schottky diode between the output and PWRGND to help prevent noise from interuppting the system.

    The same can be added between Vc and Output for similar benefits.

    Thanks,

    Daniel

  • 0 in reply to Daniel Hartung
    Prodigy 50 points

    Hi Daniel,

    The Schottky diodes that you've mentioned have already been implemented in the circuit.

    My inquiry was more related to the layout itself; again, I was looking for recommendations on the PWRGND and GND pins as they are next to each other (and needless to say, quite close in distance).

    Thanks again,

    Aki

  • 0 in reply to Aki Jupic1
    TI__Mastermind 21965 points

    Hey Aki,

    A common method for separating PWRGND and GND is not connecting them on the top layer and connecting them on other layers.

    This allows for some isolation from noise for GND while not having a large resistance in-between the two.

    Thanks,

    Daniel

  • 0 in reply to Daniel Hartung
    Prodigy 50 points

    Hi Daniel,

    Just to follow up: the only layout recommendations that you have are for the dual pack, but not the quad pack (LCCC), for this or a similar function part?

    Thanks,

    Aki

  • 0 in reply to Aki Jupic1
    TI__Mastermind 21965 points

    Hey Aki,

    The last recommendation I gave was specifically for the quad pack as the CDIP does not have separated grounds.

    The layout recommendations in the datasheet are specifically for the CDIP and not the LCCC.

    There is no app note specifically talking to the LCCC.

    Thanks,

    Daniel