Author Options:

Small led driver? Answered

I need a chip that will be able to power  5 or more LEDs not past like 10 though cause it's not necessary channels of LEDs ,I want to be able to have each channel doing different patterns at the same time, blinking ,fading ,or just on.  (it doesn't matter how much MA the chip can handle as I will be using transistors to amplify the signal ,most likely)

It needs to be able to fit in a 1/2 inch tube.

I think this one will work but im not sure. http://www.onsemi.com/PowerSolutions/product.do?id=NCP1840
I think this will only work on printed PCBs if I can i'd rather have something i can wire up with ether perfboard or wires. 



6 years ago

So, the 8 ch onsemi driver can do what you want though it's
current sink drivers.

You may have to use a PNP emitter followers to expand the
output DACs.

As far as PCB you can buy pre-made PCB squares that can
provide easy access to the IC pins.


Why does he need expansion for the outputs ?

because this chip is only 4mm x 4mm and it would be impossible to solder wires onto it. (for me any way)

I was referring to
"You may have to use a PNP emitter followers to expand the
output DACs."

not the size of the chip

Adapters exist for most smd devices...


Well that ain't one of them !

And its QFN, which really need a proper oven IMHO. They're horrible to get the solder to flow under properly.


Get an Arduino. Yes the board is larger then what you want but once you have the chip programmed you can pop it out. All you have to have is 5V going to the chip, a 16mhz crystal, the chip and your LEDs. You can put them together however you want. You can find all the info you want about setting up a bare bones arduino with a litte google search. There are also other variations of the Arduino like the nano that should fit the bill nicely. It is a bit wide at .7 inches.

Either way you go you won't need any transistors. Just the ATMEGA368 chip, 16 mhz clock crystal, power source to give 5V to the arduino, your LEDs and resistors for the LEDs.

He doesn't even need the crystal, he could use a resonator, or even the RC clock.

I've got 2 crystals specifically for that anyway. I've also done some work with an arduino before. it would be the easiest way, for me I just didn't think i'd be able to get the chip and power source to fit in my project. now i know it only needs the crystal and power to run it should be doable.

A simple power circuit like this can fit just about anywhere and take any 7V to 12V source and bring it down to the 5V needed by the Atmega chips.

the second picture if the power supply with a couple of voltage dividers added to enable an iPhone to start charging. But you see how close i have the VR and the caps.

5V converter.bmpIMG_2681.jpg

Yeah, the nano would fit nicely in the 3/4th inch tubing we need to use for this and then I could use the atmega 368 for the smaller tubing maybe well whatever's cheaper. proly the atmega. I probably will need transistors since i will be using 1-5 leds a channel.

You really have to use a PCB with the ONsemi device - it needs a little heatsinking.