Pololu Step-Down Voltage Regulator D15V70F5S3 - PL-2111 is a switch regulator which generates either 3.3 V or 5 V user selectable output voltages from an input voltage range of 4.5 V to 24 V. Regulator has a typical efficiency of approximately 90%, more efficient than linear regulators, which increases as difference between the input and output voltage is high.
Pololu Step-Down Voltage Regulator D15V70F5S3 - PL-2111 has 5 onboard connections: 3.3 V select (3V3 SELECT), enable (ENABLE), input voltage (VIN), ground (GND), and output voltage (VOUT)
Pololu Step-Down Voltage Regulator D15V70F5S3 - PL-2111 has protection against under and reverse voltage, short circuit, and overheating.
Pololu Web Site: https://www.pololu.com/product/2111/specs