/diy/ - Do It Yourself

I've decided to make a milliohm meter, using an MCU and some 7-seg displays because I have them lying around. I want to protect the MCU from seeing too high of a voltage across it (as will happen when open-circuit) so I need some sort of diode to prevent overvolting the MCU.
The MCU will be running at 5V but with an ADC reference voltage of 0.55V. There will be 537mA through the load at one range, and 0.537mA at the other range. So whatever diode I use has to be able to handle that high current, but with minimal forward leakage to not interfere with the low current (i.e. significantly below 52.4µA). My gut tells me that nothing will come close to that, but actually finding a forward leakage current value for a non-signal diode has been difficult. Picrel is from the 1N4148, which can't handle enough current to be used for this. I guess I'll probably have to measure it myself.

I'd use three 1N4004 diode drops to give 2.1V or so before they short, which should be plenty of room.

>>2406256
A: it probably doesn't matter for balance purposes
B: those look like really tiny channels for cooling compared to the axial fans of even small motors
C: are you familiar with the biot-savart law?