Application: widely used for DIY mobile power, monitor power supply, power buggies,communications equipment supply,etc. LM2596 DC-DC Buck Step-down Power Converter Module Input DC 4-40 V (input voltage must be 1.5 V higher than the output voltage, no boost). Output: DC 1.25-37 V voltage is continuously adjustable, maximum output current is 3 A. 4.0-40V to 1.25-37V LED Voltmeter