I recently bought two of these boards, https://www.sparkfun.com/products/18570 and just noticed they are different from each other, one on the back one has a jumper to cut for the Fan vcc and the other does not, it just says < 20vdc. Also if I connect a multimeter continuity check to the fan vcc and the vcc pin on the 4 pads for the fan should they be connected ? thanks
see attached pic
Hello, I designed this board. Sorry for the confusion, I’m not sure how you got sent one of the jumper-style boards, those were an earlier revision.
That board will still work fine as long as you follow the directions on the silkscreen, the reason I changed the design is because I failed to do this in testing and cooked one of my prototypes. I figured if I could make that mistake then so could a customer. The new design (the one without the jumper) is identical in every way except that there’s an “ideal diode” mosfet circuit that automatically connects the 5V line to the FANVCC but prevents it from being back-fed if you connect a higher voltage fan supply.
In short:
on the no-jumper board, you can connect up to 20VDC as an external fan supply and if it’s not there the board will just connect 5V from the on-board vreg.
on the jumper board, if you cut the jumper then there’s no connection between the 5V rail and the FANVCC, which allows you to connect an outside fan supply to that pin.
I would offer to replace your jumpered board, but we’re out of stock right now and I don’t know how long it will take to replenish, but please let me know if you have trouble with the board that has the jumper and can’t use it.
Thanks Nick for the quick reply !
