Here's something for y'all to knaw on, a 150W current-source SMPS, made with a current-mode controller. It has external monitoring and programming with0-to-5V signals.
Most power supplies have low-Z voltage-source outputs, and when operated in current-limit mode they simply servo the voltage to the achieve the desired output current. A true current source has a low effective output capacitance and its output voltage can change rapidly to maintain a constant current into a changing load.
Current-mode controllers have by their nature constant-current outputs, from the buck inductor anyway, but this is morphed into a voltage source with a big output capacitor and the controller's feedback. So I figured, why not implement one with a small capacitor and constant-current feedback? This turned out to be awkward with most controllers I considered, but NSC's (TI's) LM25117 was an exception. Among its many features is a fast current-monitor output using a cycle-by-cycle S/H circuit, which was helpful and inspiring.
My project name is PWR-758. My PCB layout uses mostly SMT parts, but I avoided the temptation to place any parts on the bottom. I got a bit carried away with bells and whistles, like programmable compliance ranges, external meter, external disable, etc., plus configuration modifications with a 10-mode jumper-header, labeled A,B,C to I, extra connectors, etc. I was forced to stop adding features when I ran out of space on my size-A schematic drawing and my4x4-inch PCB layout. :-)
When operating in constant-current mode, one option uses the controller's S/H circuit, and another option uses an LTC6102 output current-sense IC, which is fast and has very low offset voltages. The PWR-758 also has ordinary voltage-source mode options. Please take the compensation part values with a grain of salt, because I have not yet properly evaluated them, nor made a working copy of the circuit. In fact, take the entire circuit with big grains of salt!