Three-terminal LED and drive circuit thereof

摘要

A three-terminal LED and drive circuit thereof. The three-terminal LED (1) has an anode, a cathode and a gate. The three-terminal LED (1) includes a LED group (3) formed by connecting at least one LED in series and a gate circuit (2), the first end (21) of the gate circuit (2) and the anode of the LED group (3) are connected with the anode of the three-terminal LED (1), the second end (22) of the gate circuit (2) and the cathode of the LED group (3) are connected with the cathode of the three-terminal LED (1), the third end (23) of the gate circuit (2) is connected with the gate of the three-terminal LED (1).

主权项

1. A three-terminal LED drive circuit comprising a DC source and at least one branch, wherein the branch is connected between a positive terminal and a negative terminal of the DC source; the branch comprises at least two three-terminal LEDs connected sequentially and a current source having an input end, an output end and a control end in series; each of the three-terminal LEDs comprises an anode, a cathode, a gate, and an LED string comprising one LED or at least two LEDs connected in series, and a gate circuit, a first end of the gate circuit and the anode of the LED string are connected with the anode of the three-terminal LED, a second end of the gate circuit and the cathode of the LED string are connected with the cathode, a third end of the gate circuit is connected with the gate; 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 the gate circuit, the source of N-channel MOSFET (Q20) is connected with the second end of the gate circuit, the anode of diode (D20) is connected with the third end of the 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 has three operating states of cut-off, fully conduct and linear; for current flowing from the anode to the cathode: the current flows in the LED string when the gate circuit works in cut-off state; the voltage drop between the anode and the cathode is minimal and the LED string is bypassed when the gate circuit works in fully conduct state; the resistance between the anode and the cathode is variable and the voltage drop is variable accordingly, and equals a variable resistor when the gate circuit works in linear state; the at least two three-terminal LEDs are connected sequentially via connection of the anode of one three-terminal LED to the cathode of another three-terminal LED; and the control end provided by the current source is connected with all the gates of the at least two three-terminal LEDs.