Three-terminal LED and drive circuit thereof

A three-terminal LED comprising an anode, a cathode, a gate, and a LED string formed by connecting at least one LED in series and a gate circuit, the first end of gate circuit and the anode of LED string are connected with the anode of the three-terminal LED, the second end of gate circuit and the cathode of the LED string are connected with the cathode of the three-terminal LED, the third end of the gate circuit is connected with the gate of the three-terminal LED;

• based on N-MOSFET, the gate circuit comprises a N-channel MOSFET (Q20), a diode (D20) and a resistor (R20), the drain of N-channel MOSFET (Q20) is connected with the first end of gate circuit, the source of N-channel MOSFET (Q20) is connected with the second end of gate circuit, the anode of diode (D20) is connected with the third end of gate circuit, the cathode of diode (D20) is connected with the gate of N-channel MOSFET (Q20), one end of resistor (R20) is connected with the cathode of diode (D20), and the other end of resistor (R20) is connected with the source of N-channel MOSFET (Q20);
• controlled by the gate, the gate circuit of three-terminal LED has three operating states of cut-off, fully conduct and linear respectively;
• for current flowing from anode to cathode in three-terminal LED:
• the current flows in the LED string of the three-terminal LED when the gate circuit works in cut-off state;
• the voltage drop between anode and cathode of the three-terminal LED is minimal and the LED string is bypassed when the gate circuit works in fully conduct state;
• the resistance between the anode and cathode of the three-terminal LED is variable and the voltage drop is variable accordingly, and equals a variable resistor when the gate circuit works in linear state.