Operating circuit for an LED
First Claim
1. An operating circuit for at least one LED to which a DC voltage or a rectified alternating voltage is supplied and which provides a supply voltage for the at least one LED by means of a coil (L1) and a first switch (S1) clocked by a control/regulation unit (SR),wherein, when the first switch (S1) is activated, an energy is temporarily stored in the coil (L1), being discharged via a diode (D1) and via the at least one LED when the first switch (S1) is deactivated,wherein the control/regulation unit (SR) activates the first switch (S1) when a reactivation condition is reached,wherein the control/regulation unit (SR) deactivates the first switch (S1) when a deactivation condition is reached, characterised in thatthe control/regulation unit (SR) is configured to adjust the reactivation condition and/or the deactivation condition for the first switch (S1) dependent upon a present dimming levelwherein the deactivation condition is reached by monitoring a current in the operating circuit, preferably the current through a measuring resistor (Shunt, RS), andwherein below a given dimming level range, the control unit (SR) interrupts the clocking of the first switch (S1) for a given period, wherein this period is lengthened in a non-linear manner with a decreasing dimming level.
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Accused Products
Abstract
The invention relates to an operating circuit for at least one LED, said operating circuit being supplied with DC voltage or with rectified alternating voltage and providing a supply voltage for at least one LED by means of a coil (L1) and a first switch (S1) clocked by a control/regulation unit (SR). When the first switch (S1) is activated energy is temporarily stored in the coil (L1) and when the first switch (S1) is deactivated said energy is discharged via a diode (D1) and via at least one LED. The control/regulation unit (SR) activates the first switch (S1) when a reactivation condition has been met, and the control/regulation unit (SR) deactivates the first switch (S1) when a deactivation condition has been met. Said reactivation condition and/or deactivation condition can be set in accordance with the current dimming level.
8 Citations
13 Claims
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1. An operating circuit for at least one LED to which a DC voltage or a rectified alternating voltage is supplied and which provides a supply voltage for the at least one LED by means of a coil (L1) and a first switch (S1) clocked by a control/regulation unit (SR),
wherein, when the first switch (S1) is activated, an energy is temporarily stored in the coil (L1), being discharged via a diode (D1) and via the at least one LED when the first switch (S1) is deactivated, wherein the control/regulation unit (SR) activates the first switch (S1) when a reactivation condition is reached, wherein the control/regulation unit (SR) deactivates the first switch (S1) when a deactivation condition is reached, characterised in that the control/regulation unit (SR) is configured to adjust the reactivation condition and/or the deactivation condition for the first switch (S1) dependent upon a present dimming level wherein the deactivation condition is reached by monitoring a current in the operating circuit, preferably the current through a measuring resistor (Shunt, RS), and wherein below a given dimming level range, the control unit (SR) interrupts the clocking of the first switch (S1) for a given period, wherein this period is lengthened in a non-linear manner with a decreasing dimming level.
Specification