AC/DC converter, luminaire and method providing an improved start-up circuit
The present invention provides an AC/DC converter comprises an input for receiving a rectified AC input signal (Vin), an output for providing a controlled output signal (Vout) to a load ( 7 ), a switched mode power converter for transforming the AC input signal (Vin) into the controlled output signal (Vout), wherein the switched mode power converter has an input for receiving a start-up voltage (Vstart) for changing a stand-by mode of the switched mode power converter into an operating mode of the switched mode power converter, a control circuit ( 5 ) for receiving a control signal (Vctl), a kick-start power supply ( 6 ) for receiving a switch-on signal (Von) to supply the start-up voltage (Vstart) being larger than a power supply voltage (Vsup), an auxiliary power supply ( 4 ) for supplying the power supply voltage (Vsup) to the control circuit ( 5 ) and the kick-start power supply ( 6 ), wherein the control circuit ( 5 ) is arranged for activating the switch-on signal (Von) to activate the kick-start power supply ( 6 ) for turning the switched mode power converter from the stand-by mode into the operating mode.
1. A luminaire comprising:
an LED load
an input for receiving a rectified AC input signal (Vin);
an output for providing a controlled output signal (Vout) to the LED load;
a switched mode power converter for transforming the AC input signal (Vin) into the controlled output signal (Vout), wherein the switched mode power converter has an input for receiving a start-up voltage (Vstart) for changing a stand-by mode of the switched mode power converter into an operating mode of the switched mode power converter;
a control circuit for receiving a control signal (Vctl);
a kick-start power supply for receiving a switch-on signal (Von) to supply the start-up voltage (Vstart) being larger than a power supply voltage (Vsup),
an auxiliary power supply for supplying the power supply voltage (Vsup) to the control circuit and the kick-start power supply,
wherein the control circuit is arranged for activating the switch-on signal (Von) to activate the kick-start power supply for turning the switched mode power converter from the stand-by mode into the operating mode.
2. The luminaire according to claim 1 wherein the kick-start power supply is arranged for stopping to supply the start-up voltage when the switched mode power converter has changed into the operating mode.
3. The luminaire according to claim 1 wherein the control circuit is arranged for disabling the kick-start power supply after the switched mode power converter has changed into the operating mode.
4. The luminaire according to claim 1 wherein the auxiliary power supply is arranged for drawing power from the rectified AC input signal.
5. The luminaire according to claim 1 wherein the auxiliary power supply is arranged for drawing power from a battery.
6. The luminaire according to claim 5 wherein the battery is coupled to the controlled output signal (Vout) or an auxiliary output (Vaux) for receiving power.
7. The luminaire according to any one of the preceding claims wherein the kick-start power supply comprises a boost converter.
8. The luminaire according to claim 6 wherein the start-up voltage is provided to the switched mode power converter by the controlled output signal or the auxiliary output (L 3 ), after enabling of the switched mode power converter.
9. The luminaire according to claim 1 wherein the switched mode power converter comprises a transformer (T 1 ) comprising an auxiliary winding (L 3 ) for providing the start-up voltage to the switched mode power converter in the operating mode.
10. A method for providing a start-up voltage (Vstart) to a switched mode power converter comprising the steps of:
supplying a power supply voltage (Vsup) to a control circuit and a kick-start power supply;
receiving a control signal (Vctl) by the control circuit for turning on the switched mode power converter;
transforming the power supply voltage (Vsup) to a start-up voltage (Vstart), the start-up voltage (Vstart) being larger than the supply voltage (Vsup);
providing the start-up voltage (Vstart) to the switched mode power converter for turning the switched mode power converter from a stand-by mode into an operating mode.
11. The method according to claim 10 , wherein the provision of the start-up voltage (Vstart) to the switched mode power converter is stopped when the switched mode power converter has started up.