I want to build myself an adjustable bench power supply with adjustable current limiting, mainly for fun but also because I want something to help me with prototyping. I have previously built small voltage supplies using linear regulators and pots, but I want something with the current control also.

I found the L200 and it seems to do what I want it to do:

  • Voltage between 0-24V

  • Current limiting 10m-2A (these are approx)

Here's an example circuit from the L200 datasheet:

L200 Adjustable Supply Schematic

My questions are as follows:

  1. Is this a decent solution for such a device in the modern day? Are there better IC solutions than this one? Maybe one that uses less external components?

  2. Is there an easy way to control the voltage/current with an MCU? Will I have to use digital pots to replace the analogue ones, or something, to do this?

  3. When I want to set/measure the output current limit, do I simply short Vo to ground through an ammeter and adjust P1? (I am under the impression this is how you do it with retail PSUs, not sure if this works in the same way).

  4. What kind of wattage resistors should I use? My naive calculation tells me that if the max current possible is 1.5A, then the max power dissipation in R3 is 1.5^2 * 0.1 = 0.225W, so most garden variety resistors would be OK. Is this correct?

Thanks for any help!

  • \$\begingroup\$ Take a look at the datasheet. It provide a lot of useful information. \$\endgroup\$ – Long Pham May 7 '18 at 10:37
  • \$\begingroup\$ @LongPham I had a look through before posting, but I couldn't find answers to my specific questions. Let me know if I missed something :-) \$\endgroup\$ – Jaska May 7 '18 at 11:36
  • \$\begingroup\$ Barebone circuit like Figure.3 and some decoupling capacitor is enough. The Opamp isn't really neccesary. \$\endgroup\$ – Long Pham May 7 '18 at 11:42
  • \$\begingroup\$ Ok thanks, but do you mean Figure 7 in the document you linked? \$\endgroup\$ – Jaska May 7 '18 at 14:25
  • \$\begingroup\$ I'm just a little confused about doing it with a simple resistor instead of the op-amp. Do I put in a very low resistance (<10ohm) pot to control the current limit? (R3 in the datasheet example, not the example I showed) \$\endgroup\$ – Jaska May 7 '18 at 14:38

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