Electronics > Projects, Designs, and Technical Stuff

power supply woes

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KTP:

--- Quote from: CafeLogic on January 17, 2011, 09:10:48 pm ---I took a look at the datasheet for that part and you are right. According to the graph on page 8, the current will start dropping out around 1V at 50mA. That really kind of sucks. Have you considered something like this:

http://us.element-14.com/allegro-microsystems/a6279eettr-t/ic-led-driver-constant-current/dp/19M5477


--- End quote ---

That is the first part I considered, but it is labeled as obsolete and a "last time buy"  I guess the A6282 with poorer specs is replacing it  ???  They both have the same pinout though, so I *could* try to use the better part and fall back on the A6282.

As to the Pfet...busted!  I did have a reel of the IRF7104, but for the cost, you are right it might make sense to just buy a better one.  I really don't know if I am going to get reels of all of these parts or just cut-tape.  I will probably hand solder the first couple boards, but after that I may go crazy.  Still, getting the paste mask and setup for pick and place for only 80 boards will add another $1000 to $1500 to the costs.  Sigh...

CafeLogic:
I think it is time the wife learned to solder, since she is the motivating force here.  :D

Try this: http://www.silvtronics.com/order-pcbassembly.php

they might be able to do a bit better than $1000-$1500

If you decide to go the toaster route, I use these dirt cheap mylar stencils: http://www.pololu.com/catalog/product/446
They work surprisingly well.

I don't know that the A6282 isn't as good, you are just driving it to the limit, that's why it has the high dropout. Everyone makes those drivers, ST, NXP, and TI so you have tons of options.

I hope those flags are really impressive when your done.

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