LM2596 LM2596S DC-DC 4.5-40V adjustable step-down power Supply module  Name : LM2596 DC-DC Buck module Input voltage :4V ~ 35V The output voltage : 1.23V ~ 30V Output Current :3A( Max) Conversion efficiency:92%( MAX ) Output ripple: <30mV Switching frequency: 150KHz Working temperature: -forty Five~ +85 Size :43mm * 21mm * 14mm(Long*Width*Hight) Features: 1. the range of input voltage: 3.2 V to 40 V dc (input voltage must be higher than to the output voltage of 1.5 V above. Can't booster) 2. the range of output voltage: 1.25 V dc to 35 V voltage adjustable, high efficiency (92%) largest maximum output current is 3A. Instructions: 1. Power (3-40V), power indicator light, the module is working properly. 2. Adjust the blue potentiometer knob (clockwise rotation generally boost,counter-clockwise rotationTurn down) and reach with a multimeter to monitor the output voltage required voltage. Note:   Current work long hours is recommended for use in less than 2.5A, while adding bulkHeat sink (10W output above),because it is the step-down module, in order to ensure stable output Set,please keep the minimum 1.5V differential.