Model or name LM2596S DC-DC step-down module input voltage 3.2V to 40V. Output voltage 1.25V to 35V. Output current 3A (max). Conversion efficiency 92 percent (the highest). Output ripple 30mV. Switching frequency 65KHz. Operating Temperature: -45 to +85. Size: 43mm x 21mm x 14mm (L x W x H). IN + input positive: IN-input negative. The OUT + output the positive OUT: output negative. Input voltage range DC 3.2V to 40V (input voltage must be higher than the output voltage above 1.5V. Could not boost).