Adjustable buck-boost module: voltage range is DC 5.5-30V; Output voltage range is DC 0.5-30V, can be arbitrary adjustable; The output current range is 0-3A, can be arbitrary adjustable, if enhance heat dissipation, it can reach 4A; The output power can up to 35W, if enhance dissipation, it can reach 50W. With protection function: the volt transformer board is with reverse connection protection at input terminal, reverse connection will not burn; Stop the current from feeding back protection at output terminal; Short circuit protection; Backflow prevention at the output, when charging the battery, there is no need to add a second anti-backflow tube. Bright LCD display: the voltage regulator module is designed with LCD, can display input and output voltage, output current and output power; Voltage display resolution is 0.05V, current display resolution is 0.005A; Low output ripple, with LC filter Button control: the IN/ OUT button switches the display of input voltage and output voltage; Long press can switch the display of output current and output power; the ON/OFF button controls the output ON or OFF; Long press can set the default output state of the next power-on to ON or OFF. Application: the switching power supply can be applied as an ordinary buck-boost module with over-current protection; Serve as a battery charger or a high-power LED constant current driver module Features: 1. The module has IN/OUT and ON/OFF buttons: IN/OUT button switches the display of input voltage and output voltage, long press can switch output current and output power display; ON/OFF button controls output ON or OFF, long press can Set the default output state of the next power-on to ON or OFF. 2. CC is the current setting potentiometer. Turn clockwise to increase the setting current. When the load current is set to the current, it enters the constant current state,