Hey all,
I am considering powering my Nano with 12V (pin 30) and using the +5V output from the board (pin 27) to power some other components (relays, fingerprint scanner etc).
I've read the manual and they don't specify the maximum amps you can draw from the this output.
Can anyone do the maths on this one?
Thanks,
Scott.
Found something useful. The 5V is from the TI 595-UA78M05CDCYRG3..."IC, Voltage regulator 5V, 500mA SOT-223".
Does this mean I can draw the full 500mA, or is this IC also supplying power to other components on the Nano? If so, what do you think is left for my other components?
I'm thinking that the 40mA delivered from each pin is coming from the 5V regulator I'm talking about. So, I'm going to hit the nail on the head and grab myself another 5V regulator IC and set up another 5v rail on the PCB...problem solved before I have one!
There you go, you are catching on pretty quick 
Keep in mind where your new regulator gets it's input power from. If the nano become powered from the USB only then it won't be able to input power to your new regulator (USB +5vdc power maxes out a 500ma and regulator input voltage must be higher then it's output voltage) Also your external power must be able to supply the combined total current used by the Nano's regulator and your new regulator.
Lefty
Woo me! I'll be an electronics engineer in no time 
Thanks for the heads up. The power for the new regulator will be coming directly from a 12VDC battery (car battery, 700CCA), as with the power for the Nano. She'll be apples!
Cheers.
Hey Lefty,
I purchased a 5V Linear Regulator IC from the local electronics store and some caps to match. This is the data sheet: http://www.farnell.com/datasheets/64363.pdf
I've hooked it up on the breadboard as it's shown in the data sheet but it's giving me 7.5V output. I am only supplying it was 12V. Apparently it has a maximum input of 26V? How is that possible given it's meant to have a maximum output of 5V? I tried a couple of minor variations on the hookup but same result.
I'm thinking this thing is cactus...what do you reckon?
What's the problem with something having a 5V output when the input can be between 5.5V and 26V, that is a typical spec.
The fact that you are getting 7.5V from it points to the fact that it is either faulty or you have wired it up wrong.
What's the problem with something having a 5V output when the input can be between 5.5V and 26V, that is a typical spec.
Sorry Mike, you've misinterpreted what I've said a little because I chucked some extra info in the middle of my original sentence and muddled it up. Sorry, I see know how it can be misread. What it should have said is...
I've hooked it up on the breadboard as it's shown in the data sheet but it's giving me 7.5V output. How is that possible given it's meant to have a maximum output of 5V? I am only supplying it was 12V. Apparently it has a maximum input of 26V?
I know that 12V is within spec. I made note of it just to preempt someone asking me what my input voltage is.
Anyway, turns out the store had given me 2A222K capacitors instead of 22uF. I couldn't tell because I don't know a lot about electronics (still learning) and I know even less about caps. Replaced the 2A222k with the 22uF (which is what I ordered in the first place mind you)...and wollah, regulated 5v output.
Oh, and thanks for the help.
Hi Scott;
"I've hooked it up on the breadboard as it's shown in the data sheet but it's giving me 7.5V output. I am only supplying it was 12V. Apparently it has a maximum input of 26V? How is that possible given it's meant to have a maximum output of 5V? I tried a couple of minor variations on the hookup but same result."
Well that is a very strange and unusual result. The " I tried a couple of minor variations on the hookup but same result." has me a little concerned, as there is only one correct way to wire it up. A Yoda would say "no variations, just correct way" ;).
Do you have any kind of load wired to the regulator like say a 100 ohm resistor or are you reading it with the output pin floating? Are you using any recommended input and output capacitors that the data sheet might recommend. I've not used that series of regulators before but have used dozens and dozens of the 78XX and 79XX series and never had a bad one. They are pretty much industructable because of their automatic foldback/shutdown features on over current and over temperature.
I guess you can only review the hook up once again. Source voltage is 12vDC (not AC), 12v wired to corrent input pin, ground pin of regulator wired to ground of 12v external source, measured output between correct output pin and ground, install capacitors to insure regulator is not oscillating, check voltage with output wired to a resistor load. Then check again.
Lefty
Hey Lefty.
Thx for the lengthy response. Looks like I posted back while you were typing your last post!
When I said "minor variations"...what I was doing was changing the order of the 12V, capacitor and pin 1 on the breadboard. So for instance:
VCC-CAP-Pin 1 vs CAP-VCC-Pin 1
Technically makes no difference but only took me a second and put my mind at ease before heading back to the store only to possibly look like an idiot.
Turns out it was the cap on the output pin. They'd given me something way too small. There's a new guy at the store who apparently knows less than me!
All solved now, thanks