I'm looking for a solution to drive the coil of a relay (G7L-2A-X DC24). It requires 24 V, which can be reduced to 50% holding voltage after 100 ms.
My initial thought was to build a generic buck converter circuit with 24 Vin and to drive the MOSFET using a µC programmed to drop the duty cycle from 100% after 200 ms. No feedback since the load is fixed, just finding the duty cycle through trial and error using a multimeter.
I'm wondering if I can simplify this circuit. Is the diode necessary and could I leave out the inductor, as the relay coil itself will have a certain inductance?
I'm also unsure about the values to use for the capacitor (and the inductor, potentially) and about the switching frequency (probably on the higher end? to reduce component size and since switching losses aren't really a concern in a MOSFET this small).
Lastly, just driving the coil with a 50% PWM signal isn't really an option, as I think that would cause too much EMI for the hall effect current sensor next to it. Its datasheet does state that it uses differential probing to minimize interference and my theory is that I can calibrate for any remaining error if the field is constant.