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I am using an arduino to create a device that outputs a specific current and voltage. I was wondering if there are any devices out there such as dc/dc buck boost converters that can be controlled by arduino to output desired powers. I am looking for something rated for at least 50 watts that can carry at least 3 amps of current.

Thank you all in advance!

  • I've seen I²C controlled digital potentiometers. I know you can set the output voltage of some power supplies with a pot. If you can also control the current, you could control both properties with a pair of digital pots. – Duncan C Mar 6 at 0:51
  • What is the desired input voltage? – Roberto Lo Giacco Mar 6 at 1:22
  • @RobertoLoGiacco I currently have a power suppy input voltage of 12V. – Henri Cousino Mar 10 at 20:42
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Yes, and it's actually far simpler than most realize. I've tried digitpots, but they are quite un-linear and only handle 5v, unless you spend $$$. Early on, i had soldered an LDR in parallel to a buck converter's adjustment pot, and fed that PWM. It worked to somewhat adjust the vout, but had a lot of ripple and was not linear. I had gotten an MCU-controlled linear PSU going, that wasn't too hard, but i always wanted a buck. Just recently, i've found an awesome method and built several MCU-controlled SMPSs. You don't have to have any special parts or de-solder anything!

Basically, you:

  • use a buck/boost (or dual) with a built-in V-adj potentiometer.
  • use a lowpass to convert the MCU's PWM output into a 0-vcc signal.
  • feed smoothed PWM voltage to a unity gain opamp to buffer available current.
  • create a common ground between MCU and SMPS.
  • feed the buffered 0-vcc control through a resistor into the pot's wiper, ~200-1k.
  • the amount of "injected" voltage will be inversely proportional to the SMPS's output voltage.

Since most SMPS's feedback is in the area of 1-2.5v, the 0-3.3/5v output of the MCU works well to provide or take away feedback from the regulator. The best part about this scheme is that output voltage regulation is maintained by the SMPS's hardware, the MCU just sets an offest. In short, you can set it to 10v via the MCU, attach a big load, and the voltage stays at 10v!

I've used this technique on the xl4005 and the xl4015, but i would imagine it would work for just about any common driver package.

  • This is a voltage regulator, the OP asked for a voltage AND current control circuit – Roberto Lo Giacco Mar 10 at 22:10
  • @RobertoLoGiacco If you can control the voltage, you can control the current as well. The simplest would be to use the MCU, which probably suffices for loads like motors and heaters. For LEDs or instrumentation, you probably want hardware control. There's many "current limiting" circuits one could place in-line as well, simplest likely being a current shunt with op-amp amplifier driving an NPN darlington in a series-pass regulator or using the opamp to invert and amplify and supplement the SPMS feedback like described above for voltage. If OP wants, I can sketch something out... – dandavis Mar 12 at 18:23

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