Device for controlling a field effect transistor
View Patent ↗A device for actuating at least one field effect transistor corresponding to a control signal present at a control line, includes at least one driver circuit having a current mirror with an input side and an output side. Both the input side and the output side are connected to a supply voltage, the input side is connected to the control line via a level converter and the output side is connected to the at least one FET.
1. A device for LED actuation corresponding to a control signal present at a control line, the device comprising:
at least one field-effect transistor (FET) for bypassing at least one respective light-emitting diode, said at least one field-effect transistor having a gate connection, a source connection and a drain connection and being an N-channel FET with a floating source potential with respect to the control line;
at least one driver circuit including a current mirror having an input side and an output side for transmitting a current flowing on said input side to said output side, said input and output sides being connected to a supply voltage;
said current mirror including a transistor pair having an input-side transistor and an output-side transistor with base connections connected to one another and to a collector connection of said input-side transistor;
a level converter formed by a current sink and connecting said input side of said current mirror to the control line in order to impress a current being dependent on a voltage of the control signal;
said output side of said current mirror being connected to the gate connection and to the source connection of said at least one field-effect transistor; and
a gate resistor connected between the gate connection and the source connection of said at least one FET.
2. The device according to claim 1 , wherein said transistor pair is a double transistor.
3. The device according to claim 1 , wherein said current sink has a level converter transistor and a level converter resistor, said level converter transistor is connected in series with said input side of said current mirror, and said level converter transistor has an emitter connection related to ground via said level converter resistor and a base connection connected to the control line.
4. The device according to claim 3 , which further comprises a collector resistor connected between said level converter transistor and said input side of said current mirror for reducing a power loss at said level converter transistor.
5. The device according to claim 1 , which further comprises an input series resistor connected between said input side of said current mirror and the supply voltage and an output series resistor connected between said output side of said current mirror and the supply voltage.
6. The device according to claim 1 , which further comprises an input series resistor connected between said input side of said current mirror and the supply voltage.
7. The device according to claim 1 , which further comprises an output series resistor connected between said output side of said current mirror and the supply voltage.
8. The device according to claim 1 , which further comprises a charge pump or a boost converter supplying an output voltage being the supply voltage.
9. The device according to claim 1 , wherein said at least one field-effect transistor includes two or more field-effect transistors, and said at least one driver circuit includes two or more driver circuits having a common supply voltage, being connected in parallel, and actuating said field-effect transistors.
10. The device according to claim 9 , wherein said two or more field-effect transistors are each connected in parallel with a respective LED disposed in at least one series circuit.