Minimal effort to use the MAX
Well, it's been a while. Over the holidays, I played with a toy robot. It's a little tank-like thing right now. Anyway, I was driving the motors with 4x AA and the Arduino with a 9V. I was pushing 10 IR LEDs constantly and could watch the voltage from the 9V drop quickly while running. By the time the motors killed the AAs, the LEDs killed the 9V.
So I needed to get away from the shunt regulator (7805) and need either a buck or a boost regulator instead. I did some extensive hunting on digikey and found a MAX1674 that sounded ideal as a boost regulator. A nice simple circuit and I can boost voltage from 2x AA to 5V. Add to cart. Add additional items to cart. Place order. Wait patiently. Get box, open, pull out pack of chips, what am I in for? I should have read the spec sheet closer. The MAX1674 chip measures just 3mm x 3mm. I knew it was surface mount, but didn't pay attention to the size. I also didn't pay attention to the size of those additional parts. Most of the resistors and the 100nF caps I picked up are 0402 parts.
Ok, no problem. I will make it work. I'll just fire up Fritzing and find a part with the same footprint. Nope, not in there. Shit. Now I have to make a part for Fritzing. So I threw down a standard surface mount 8-pin chip, create a custom part, and export the FZPZ file. I used Inkscape to edit the SVG files and then repackaged the FZPZ as a new part. Maxim calls the footprint 8UMAX, I just called it UMAX8. I know, creative, right? It didn't take much effort to create the footprint, and as you can see, I tie the ground pin to a ground plane under the pin. I printed out the drawing to show the chip compared to standard 0.1" headers. If you're interested, you can download the FZPZ file here and import it into your parts bin inside of Fritzing.
Now, I've already laid out and put together a board with this sucker on it. It works good, better than I expected actually. I've got a lot to say about it too, so I'll save that for a separate post.