I am in the process of designing a PCB that is powered by a 10V / 1mA supply from a fandeck (incorporating EC/DC fan motors).
One of the functionalities include having continuity between 2 pins on the PCB (Volt free contacts), which are connected to an external controller (Master). Since the supply can only supply 1mA, I am using 2 n-channel Mosfets for their high input resistance. However, I don't know how to switch them since they're connected to an external circuitry with different voltage references (grouds), and the mosfet switching works around the gate to source voltage (Vgs(Threshold)).
I also saw the attached picture in an application note from Texas Instruments (Application Report SLVA948–December2017), But I don't have any prior experience with charg pumps and am a little bit worried regarding their current draw and I also don't know the voltages that master controller might exert to check continuity so i don't know how higher the voltage should be when fed into the gates.
I am already familiar with gate drive design so that is not an issue. Is there a better way of doing this with less current draw?
any help would be highly appreciated.
Many thanks in advance for your time.