Driver for LED device and LED system
A single-stage driver for an LED device, configured to be coupled between a power supply and the LED device, comprises: a rectifier, a DC-to-DC converter, a resistor and a controller. The rectifier is configured to be coupled to the power supply and convert an alternating voltage from the power supply into a first direct voltage. The DC-to-DC converter, which comprises at least two switches, is coupled between the rectifier and the LED device and configured to receive the first direct voltage and provide a constant current to the LED device. The resistor is configured to be coupled in series with the LED device. The controller is coupled between the resistor and the at least two switches, and configured to keep the current through the LED device stable around a predetermined current value by controlling the switches based on a voltage across the resistor, wherein all the at least two switches are turned on or off synchronously.
1. A single-stage driver for an LED device, configured to be coupled between a power supply and the LED device, the driver comprising:
a rectifier, configured to be coupled to the power supply and convert an alternating voltage from the power supply into a first direct voltage;
a DC-to-DC converter, coupled between the rectifier and the LED device and configured to receive the first direct voltage and provide a constant current to the LED device, the DC-to-DC converter comprising at least two switches, wherein the at least two switches comprises a first switch, a second switch and a third switch, wherein the DC-to-DC converter further comprises an inductor, a first diode, a second diode, a third diode and a first capacitor; the power supply is configured to charge the inductor via the first, second and third switches when the first, second and third switches are on; the inductor is configured to discharge via the first diode, the first capacitor, the third diode and the second diode when the first, second and third switches are off;
a resistor, configured to be coupled in series with the LED device; and
a controller, coupled between the resistor and the at least two switches and configured to keep the current through the LED device stable around a predetermined current value by controlling the at least two switches based on a voltage across the resistor, wherein the at least two switches are turned on or off synchronously.
2. The driver according to claim 1 , wherein the alternating voltage of the power supply is in a range from about 200V to about 500V.
3. The driver according to claim 1 , wherein the controller is configured to receive the voltage across the resistor and generate a control signal according to the voltage for controlling the at least two switches.
4. The driver according to claim 1 , wherein the at least two switches comprises a first switch and a second switch, wherein the DC-to-DC converter further comprises an inductor, a first diode, a second diode and a first capacitor, wherein the power supply is configured to charge the inductor via the first and second switches when the first and second switches are on; the inductor is configured to discharge via the first diode, the first capacitor and the second diode when the first and second switches are off.
5. The driver according to claim 4 , wherein the first switch, the inductor and the first diode are coupled in series between a first output terminal of the rectifier and a first terminal of the LED device, an anode of the first diode is coupled to the inductor, a cathode of the first diode is coupled to the first terminal of the LED device, a cathode of the second diode is coupled to a node between the first switch and the inductor, an anode of the second diode is coupled to a second output terminal of the rectifier, a first terminal of the second switch is coupled to a node between the inductor and the first diode, a second terminal of the second switch is coupled to the second output terminal of the rectifier, the first capacitor is coupled between the first terminal of the LED device and the second output terminal of the rectifier.
6. The driver according to claim 1 , wherein the first switch, the second switch, the inductor and the first diode are coupled in series between a first output terminal of the rectifier and a first terminal of the LED device, a first terminal of the inductor is coupled to the second switch, a second terminal of the inductor is coupled to an anode of the first diode, a cathode of the first diode is coupled to the first terminal of the LED device, the second diode and the third diode are coupled in series between the first terminal of the inductor and a second output terminal of the rectifier, the third switch is coupled between the anode of the first diode and the second output terminal of the rectifier, the first capacitor is coupled between the first terminal of the LED device and the second output terminal of the rectifier.
7. An LED system, comprising:
an LED device; and
a single-stage driver for driving the LED device, configured to be coupled between a power supply and the LED device, the driver comprising:
a rectifier, configured to be coupled to the power supply and convert an alternating voltage from the power supply into a first direct voltage,
a DC-to-DC converter, coupled between the rectifier and the LED device and configured to receive the first direct voltage and provide a constant current to the LED device, the DC-to-DC converter comprising at least two switches, wherein the at least two switches comprises a first switch, a second switch and a third switch, wherein the DC-to-DC converter further comprises an inductor, a first diode, a second diode, a third diode and a first capacitor; the power supply is configured to charge the inductor via the first, second and third switches when the first, second and third switches are on; the inductor is configured to discharge via the first diode, the first capacitor, the third diode and the second diode when the first, second and third switches are off;
a resistor, coupled in series with the LED device, and
a controller, coupled between the resistor and the at least two switches and configured to keep the current through the LED device stable around a predetermined current value by controlling the at least two switches based on a voltage across the resistor, wherein the at least two switches are turned on or off synchronously.
8. The LED system according to claim 7 , wherein the alternating voltage of the power supply is in a range from about 200V to about 500V.
9. The LED system according to claim 7 , wherein the DC-to-DC converter comprises a buck-boost circuit.
10. The LED system according to claim 7 , wherein the DC-to-DC converter comprises a three-level circuit.
11. The LED system according to claim 7 , wherein the predetermined current value is a rated current value of the LED device.
12. A single-stage driver coupled between a power supply and an LED device, the driver comprising:
a rectifier, coupled to the power supply and converting an alternating voltage from the power supply into a first direct voltage;
a DC-to-DC converter receiving the first direct voltage from the rectifier and providing a constant current to the LED device, the DC-to-DC converter comprising a first switch, a second switch and a third switch, an inductor, a first diode, a second diode, a third diode and a first capacitor, wherein the power supply is configured to charge the inductor via the first, second and third switches when the first, second and third switches are on, and wherein the inductor is configured to discharge via the first diode, the first capacitor, the third diode and the second diode when the first, second and third switches are off;
a resistor coupled in series with the LED device; and
a controller, coupled between the resistor and the first, second and third switch and configured to keep the current through the LED device stable around a predetermined current value by controlling the first and the second switch based on a voltage across the resistor such that the first and second switches are turned on or off synchronously.
13. The driver according to claim 12 , wherein the first switch, the second switch, the inductor and the first diode are coupled in series between a first output terminal of the rectifier and a first terminal of the LED device, a first terminal of the inductor is coupled to the second switch, a second terminal of the inductor is coupled to an anode of the first diode, a cathode of the first diode is coupled to the first terminal of the LED device, the second diode and the third diode are coupled in series between the first terminal of the inductor and a second output terminal of the rectifier, the third switch is coupled between the anode of the first diode and the second output terminal of the rectifier, the first capacitor is coupled between the first terminal of the LED device and the second output terminal of the rectifier.