# Circuit design with multiple voltage levels

I'm working on an art piece based around an Arduino Mega that essentially requires power for three types of devices:

• Solenoids (4): 24 V, ~100 mA a piece (400 mA, 9.6 W total)
• NeoPixel LEDs (1280): 5 V, ~60 mA a piece (77 A, 384 W total)
• Base stepper motor (1): 5 V, not really an issue because it can be powered with an H-bridge driver from the output of the Arduino

Since the LEDs are the primary current consumer here, we're thinking we'll use this 600 W, 5 V DC power supply (SE-600-5): http://www.meanwellusa.com/webapp/product/search.aspx?prod=SE-600

This power supply has three pairs of output terminals, and is rated for enough current to power the LEDs.

The concern here is how to step up that voltage from 5 V to 24 V to power the solenoids (with enough current). We are considering voltage regulators, boost converters, as well as a high voltage amplifier like the PB64 from Apex Technology (shown in Figure 4 here: https://www.digikey.com/en/articles/techzone/2018/apr/how-to-combine-high-and-low-voltages-in-a-single-design)

Does anyone have any experience with issues like this? How would you recommend managing two voltage levels?

Thanks so much!

• Why don't you just buy a separate 24V power supply? Do you have mains ac power available or something else? – Elliot Alderson Aug 8 '18 at 20:26
• @ElliotAlderson thanks for answering...I'm a big fan ;-) We're trying to avoid getting two power supplies for space limitations etc., but it's not out of the question. Mains AC power yes – Ali Na Aug 8 '18 at 20:27
• (1) "From 5V to 24V ... we are considering ...buck converters ..." did you mean boost converter instead of buck? (2) The high voltage amplifier can amplify a signal, but requires a high voltage supply rail. It can't generate high voltage for itself. (3) Can you find a solenoid which works on 5V? If so, the solenoid and the LEDs could share the 5V supply. – Nick Alexeev Aug 8 '18 at 20:35
• Consider using opto-couplers to isolate Arduino digital I/O from those high-current spiky loads. The DC supply for Arduino can then be an isolated supply, separate from the DC supply for those heavy loads. – glen_geek Aug 8 '18 at 20:54
• 24V supply is easy. Distributing 77A without a a layout plan for heavy cabling will be a problem. You ought to define wire lengths and gauges to each of the eight 5m reels and keep the 24 V separate due to transient issues and use a very low ESR cap to decouple solenoid impulses from supply with power reverse clamp diodes across switches with shielded cables. – Tony Stewart Sunnyskyguy EE75 Aug 8 '18 at 22:36

IMO it would make much more sense to use an SE-600-24 and use buck convertors to create a local +5V supply for your LEDS.

You have the potential to need conductors that will support many 10's of amps (if you have 4-5 major wiring runs) if you use a 5V supply and it is best to get this done at the highest voltage and lowest current possible. Running 5V any distance you will end up with significant voltage lose, and may end up with signal ground problems for your LED data.

There are plenty of 2-5A Buck convertors like this, this (I've used a bunch of these and I like the input capacitors) or this available at low cost that would support groupings of up to 50+ of your LEDs allowing much smaller wires to be used in your installation.

• Thanks for this info and your thoughtful response. My worry is that if I use the buck converters w/ 2-5 A ouput, I'd need so many of them (~5 even if we were to run at half power). I guess this would be okay, as we could just run the outputs to different sections of the LED strips. Any thoughts? – Ali Na Aug 9 '18 at 18:13
• @AliNa Exactly, you simply power smaller section of your array. I think that the savings and convenience of smaller more flexible wire would be far more than the cost of the Buck convertors ...you can get then for less than $1 each in small quantity. – Jack Creasey Aug 9 '18 at 18:52 There are a few ways to do this: 1) Use a separate 5V and 24V supply, the advantage is you don't need any DC to DC controllers in the design, this would likely be the cheapest and least complex method. Some AC to DC supply's have swapable modules that would allow you to generate both voltages in one supply. 2) Use 24V and use voltage regulators or DC DC buck converters to step down the voltage to 5V. The advantage to this is only one 5V buck DC to DC converter would be needed. The disadvangtage would be that 5V buck converter would be large (and expensive) you would also have losses of roughly 80% to 90% in the DC to DC converter. Off the shelf DC to DC converters mostly range from 0.5$ to 1% a watt.

3) Use 5V as the main rail and step up the 24V with a boost converter. The advantage is the boost converter would only need to handle 10W

You can use a boost converter to get the 24V from the 5V.

For example, the ITX0524SA, can boost a voltage in the 4.5V-9V to 24V @250mA (for your application may need two, but this is just an example to give you an idea). You can find one with more power capability. This is more like a standalone solution.

You may use an IC such as the LM27313 (for example). This one can You can use a boost converter to get the 24V from the 5V. For example, the LM27313, can boost a voltage in the 2.7V-14V to voltages up to 28V @800mA. This should be able to power the 4 solenoids (400mA @24V). Efficiency may not be great at that power for this particular IC but this is just a guideline. This requires more work since you'd have to add the external components but could be cheaper.