It is a DC constant voltage constant current step down power supply module.It can be used as ordinary buck power supply module, charger and LED constant current driver.Simple and efficient, practical. 2. Features: 1>.High input voltage; 2>.Stable voltage output; 3>.Support over temperature protection; 4>.Support overvoltage protection; 5>.Support short circuit protection; 6>.Low power consumption; 7>.Support constant voltage constant current output; 8>.Support charging function;\n9>.With heat sink and keep good heat dissipation. 3.Parameters: 1>.Product Name:12V 3A DC Step Down Power Supply Module 2>.Working Voltage:DC 16V-120V(Keep input is at least 4.0V high than output) 3>.Output Voltage:DC 12V 4>.Output Current:3A 5>.Output Power:36W 6>.Conversion efficiency:About 96%(The smaller the differential voltage, the higher the efficiency) 7>.Working frequency:140KHz 8>.Soft Starter:Yes(Failure at high power load) 9>.Over temperature protection:Yes 10>.Overvoltage protection:Yes11>.Short circuit protection:Yes12>.Working Temperature range:-40?~85? 13>.Working Humidity range:0%-95%RH 14>.Size:42*30*20mm 4.Using Steps: 1>.Connect right input voltage at input terminal. 2>.Turn ON power supply. 3>.Check output voltage by voltmeter and ammeter. 4>.Connect load.