A PSoC-Based Digital Load Box

If you’ve ever had to build a power supply, you may have needed to test it to a certain current limit. Too often, the way to do this is by stacking up large wattage resistors in series and parallel until you’ve got something that approximates the load you want. I got tired of doing this, and whipped up this little tool to help me test my power supplies with a little more aplomb. I’m a big fan of the Cypress PSoC line of processors, which is on our FreeSoC2 Development Board, so I decided I’d use a FreeSoC2 to implement my load. The PSoC has a huge advantage over other systems in that it has a lot of onboard analog circuitry (four op-amps), true 8-bit DAC outputs (instead of PWM), a high-accuracy 16-bit differential sigma-delta ADC and a couple of channels of SAR ADC. With all of this onboard power, I was able to reduce the external circuitry down to a few resistors and a FET as a load element.”

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