LM2596 adjustable step down regulator... need a little bit of help and advice.

Discussion in 'The Projects Forum' started by Evil Lurker, Feb 11, 2013.

  1. Evil Lurker

    Thread Starter Member

    Aug 25, 2011
    117
    23
    Ok so I have begun work on the PCB layout. Decided to go with ExpressPCB. Downloaded program, started playing with it, found out that there is no SMD pad in the default library and no custom component file to be found on the net that someone else has created for this particular IC. So, basically it looks like I am going to have to create my own.

    After a couple hours of reading, tinkering, and what not I got the hang of how to create custom pads, group them together, and save the whole thing as custom footprint. The whole trick seems to be create a set of custom pads according to the measurements in the datasheet, set your snap to grid waay small, zoom in, and put the pads where they need to go. The deal is I'm not exactly for sure what grid spacing I need to use to ensure that the 5 pins coming off the TO-263 smd package line up properly so that I won't have any issues connecting traces and what not.:confused:

    Anyhoos, FWIW it looks like the pins are on 1.07mm centers, and per the datasheet coincidentally the solder pads are almost exactly the same size as a 1206 case resistor. I think I got a fairly decent footprint saved, but, that said I used metric measurements to make it since it seems a lot easier for me to use the metric system since all the numbers are based on 10 and not 12. So, should I do the whole PCB in metric or try and swap it over to imperial? Also what sort of grid spacing should I be using to make sure that everything gets lined up?

    *Sigh* I will be soooo glad to get this stinking layout done... I love electronics but jeez I hate numbers.
     
  2. bountyhunter

    Well-Known Member

    Sep 7, 2009
    2,498
    507
    Contact TI which now owns Nat Semi. Bug the marketing people for a pad layout. It should be on the data sheet.

    To add:

    It is on the data sheet.
     
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