This is a DC to DC Adjustable Step-down (Buck) 3A voltage regulator board. This regulator module is based on LM2596S-ADJ SMPS chip which supports 150 KHz PWM for output regulation. Input and output supply is filtered by capacitor and inductor for quality and stable out put performance over a wide input supply range. Input voltage should be 3.2V to 40V DC, Input is marked as +IN, -IN. Output is marked as +OUT, -OUT will be in the range of 1.25V to 35V DC. Input voltage must be 1.5V higher than desired output voltage. There is an on-board pot for setting the output voltage. Maximum output load can be 3A range, it should be supported by 3A input DC voltage.