There is a certain system (PCB) which is built around an ARM microcontroller. In order to test the system, I used a DAQ by National Instruments which is able to simulate various conditions (both analog and digital) that enable me to fully test the device.
So here is the problem - One of the central tests is to measure the leakage current of the board when the MCU sleeps. Normally this works fine and the readings are in the tens of microamps. When the NI DAQ pins are connected this figure goes up much higher, to a point that the test makes no sense at all. Disconnecting all the pins physically solves the problem, however this is not something I can do as the tests should be fully automatic.
I was thinking about using some form of bi-directional tri-state buffers in order to disconnect digital pins (they function as I/Os) when testing leakage and use mechanical relays for analog pins. This is in order to reduce the number of required relays.
Any other way out of this? I think I'll be able to tolerate a leakage of 1 to 2uA. System runs on 3.3V.