# Outputting 10V from 7 ports, low current

I'm working on a school project with a lighting unit that has seven inputs that read between 0-10VDC. I need some sort of microcontroller, relatively inexpensive, that can be programmed to output what I want to these seven inputs with that voltage range. Would something like an Arduino Mega be sufficient, with voltage doublers to get from 5V to 10V, to send those voltage outputs to our lighting unit? I realize I may also have to use something to convert the PWM signal closer to DC, suggestions on that would also help :)

• It would help to know more about the inputs - how are they driven now, what current do they require, etc. That will control what you can get away with. Feb 2, 2015 at 5:17
• Are the inputs digital, or analog? Feb 2, 2015 at 12:26
• The inputs are analog Feb 5, 2015 at 23:43

Would something like an Arduino Mega be sufficient, with voltage doublers to get from 5V to 10V, to send those voltage outputs to our lighting unit

If you use a gain-of-two op-amp amplifier, you will probably need a supply voltage of 11 or 12 V for that circuit. With a 10 V supply, even if you choose a "rail-to-rail" output op-amp, you will probably not get an output above 9.9 V or so. Also watch out that the available current can get very limited as you try to get the op-amp output close to the rail. If your "low" current requirement is 1 uA, you'll be okay; if it's 10 mA, you'll probably need more supply headroom.

If 9.9 V is okay, then powering the amplifier circuit from a voltage-doubled 5 V could be made to work.

If a voltage doubler won't work, and you don't already have, say, a 12 V supply available, you can use a boost converter circuit to generate 12 or 15 V from your existing 5 V supply.

I may also have to use something to convert the PWM signal closer to DC

All you need is a low-pass filter. A simple one can be implemented with just a resistor and capacitor (search for "RC filter"). If you want lower ripple than a single-pole filter gives you, you can likely combine a two-pole low-pass filter function with your 2x gain function in an op-amp circuit.

Here is what I would do.

Create a 10V rail by whatever means is suitable. Charge pump regulator or typical inductor-based boost converter.

Get two quad high-voltage level shifters (CD40109B). These can convert your 5V PWM signals to 10V PWM signals. There are 4 channels in each IC. So you will have one extra channel. Pull the unused input high or low. Do not leave any inputs floating.

Put an RC filter on the output of each channel. (Series R and shunt cap). Choose RC so that RC >> PWM period. If you can manage to set RC = 5 periods, or more, I suspect the results will be OK, but you can fine tune as needed. R should be 10k or more to avoid overloading the IC. They cannot put out a lot of current.

The op-amp idea would be good if you had an analog output. But since you have a PWM output, it will be cheaper and easier to convert to 10V in the digital domain.

• You could also probably use two quad comparators to level shift your PWM signals. Keep inverting inputs at 2.5V. Feb 2, 2015 at 8:03