HardwareChap
Junior Member level 1
I've seen two latching relay circuits with different back EMF diode protection configurations. I can understand how one circuit works, but I'm not sure how the other does. In the circuits below, I understand how "Circuit B" works, when the FET turns off the voltage on the connection to the drain (and anode of D3/D4) rises, this forward biases the diode and the current then circulates though the coil and diode. In "Circuit A", I can't see how the back EMF is dealt with