RELAY DRIVER SPEEDS SWITCHING WHILE HANDLING HIGH CURRENT

摘要

The final circuit uses the relay coil as the switching inductor, and it simply passes the resulting current through a resistor sized to provide the 1.21-V reference feedback voltage when the relay coil reaches rated current (see the figure). The LM2674 is a garden-variety, high-volume part that is cheap and readily available, but most any downswitcher chip rated for sufficient voltage (a maximum 30-V input in this case) and current (70 mA maximum per coil here) could do the job.