The LMR14203XMK/NOPB is a SIMPLE SWITCHER PWM DC/DC Buck (Step-down) Voltage Regulator with a wide input range from 4.5 to 42V, it is suitable for a wide range of applications such as power conditioning from unregulated sources. They feature a low RDSON (0.9R typical) internal switch for maximum efficiency (85% typical). Operating frequency is fixed at 1.25MHz allowing the use of small external components while still being able to have low output voltage ripple. Soft-start can be implemented using the shutdown pin with an external RC circuit allowing the user to tailor the soft-start time to a specific application. The LMR14203XMK/NOPB is optimized for up to 300mA load current. Additional features include thermal shutdown, VIN under-voltage lockout and gate drive under-voltage lockout.