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UA78M33 - Incorrect Footprint?

Sam Cleaver
Prodigy 40 points

Hi There,

I've recently started using the TI provided footprints for CAD design. It appears that the footprint for the UA78M33 does not match the datasheet (http://www.ti.com/lit/ds/slvs059r/slvs059r.pdf):

For DCY (and pretty much any package) the pin from right to left (top view excluding common tab)is:

  1. Input
  2. Common
  3. Output
However the BXL file for this package assigns the pins as:
  1. Output
  2. Common
  3. Input
Obviously it's a pretty big problem; I made the fatal error of not ensuring the footprint matched the datasheet before manufacture and so have had the regulator giving out ~10V (power supply 12V), and the regulator then frying my 3V3 components and eventually itself. Can you confirm if the footprint is indeed incorrect or am I missing something?
  • 0
    TI__Guru**** 164656 points

    Sam,

    For DCY (and pretty much any package) the pin from left to right (top view excluding common tab)is:

    1. Input
    2. Common
    3. Output

    Did you mean left to right?

    Do you have a URL to the location of the BXL file?

  • 0 in reply to Ron Michallick
    Prodigy 40 points

    Hi Ron,

    It looks like all of the UA78M33 footprints are the wrong way round, I don't think its my use of them as the 7805 footprints are fine. I've included an image below to better illustrate the problem. (Sorry for the confusion, I agree left to right should be input, common, output; however on the footprint it is output, common, input)

    Datasheet: http://www.ti.com/litv/pdf/slvs059r

    BXL: http://webench.ti.com/cad/dlbxl.cgi/TI_BXL/UA78M33_DCY_4.bxl

    From: http://www.ti.com/product/ua78m33