Electronic – What’s the purpose of this diode in this level-shifter


look at this circuit:


I don't get that what's the usage/purpose of the BAS316 in this circuit?

Best Answer

One purpose for that diode is to block a leakage current path if the +3VRUN rail is powered up but that the +5VRUN rail is not powered up. Allowing an unpowered rail to get leakage current from other powered circuits can lead to operational problems and potentially result in severe latch-up in circuits referenced to that rail when they become powered.