Hello,
I have an HMC8043 power supply here, on which I noticed some weird behaviour when using very low current limits.
I was playing around with some solar-powered things that I wanted to power from the HMC8043 to take some measurements. I did set the current limit to the lowest possible value of 0.5mA, but it somehow doesn't respect that (reliably). I can pull up to around in 4.5mA in CV until the OCP triggers and it switches to CC mode. I could understand if the supply couldn't measure such small currents, but it shows the value, so it knows but doesn't care.
I couldn't find anything specific in the datasheet besides "0.05% + 2 mA" readback accuracy, also it is pretty accurate and once the OCP is triggered it regulates pretty accurately to the 0.5mA but I have to go well over the set limit to make that happen.
Is this a normal behaviour? Probably a supply like the NGL/NGM/NGU series would be rather made for that job (at least they are specified to be more accurate at low currents) but those are quite expensive and I don't use these low limits (especially THAT low) often, also the HMC8043 pretends it can do it, but somehow doesn't.
It is the most recent firmware (01.400) installed on the supply.
I noticed that sometimes there are R&S-people around here, maybe someone there has some insights

.
I did shoot a short video to show the behaviour, for simplicity I did just measure two LEDs there (sorry for the messy desk):