LED controller comprising a clocked current source
AssigneeTridonic GmbH & Co KG
InventorsMichael Zimmermann, Eduardo Pereira
Life of this patent
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Abstract
The invention relates to an LED driver circuit comprising: a circuit block for providing an adjustable DC voltage and a clocked constant current source, e.g. a DC/DC converter that is supplied with the DC voltage, comprising a switch that is clocked by a control circuit in such a way that a reduction of the activation period ton of the switch leads to a reduction in the provision of power. One or more LEDs can be supplied from the constant current source and in addition to reducing the activation period t0N, the control unit is designed to change at least one other control variable of the constant current source or the circuit block in order to provide the direct current.
Claims22
An LED operating circuit, having:
- a circuit block for providing an adjustable DC voltage, and
- a clocked constant current source, supplied with the DC voltage, with a switch (S), which is clocked by a control circuit in such a way that a reduction in the switch-on time period ton of the switch (S) results in a reduction in the power provision, wherein, starting from the constant current source, one or more LEDs can be supplied,
- wherein the control unit is designed to vary at least one further control variable of the constant current source or of the circuit block for DC provision, in addition to the reduction in the switch-on time period (ton), and
- wherein the control unit is designed to reduce the power provision of the constant current source by varying the at least one further control variable of the constant current source or of the circuit block for DC provision, in case the switch-on time period (ton) corresponds to a preset minimum value (ton_min).
A method for operating at least one LED, with an LED operating circuit, comprising:
- generating an adjustable DC voltage, and
- clocking a constant current source, supplied with the DC voltage, with a switch (S) in such a way that a reduction in the switch-on time period ton of the switch (S) results in a reduction in the power provision, wherein, starting from the constant current source, one or more LEDs are supplied,
- wherein at least one further control variable of the constant current source or adjustable DC voltage is varied, in addition to the reduction in the switch-on time period (ton), and
- wherein the control unit reduces the power provision of the constant current source by varying the at least one further control variable of the constant current source or adjustable DC voltage, in case the switch-on time period (ton) corresponds to a present minimum value (ton_min).
Dependencies are inferred from the claim text.