DRIVER CIRCUIT FOR SUPPLYING A CONSTANT CURRENT TO AN LED ARRANGEMENT

Abstract: a driver circuit for supplying a constant current to an led arrangement, which is formed by a step-down converter including, in series with a coil, a current measuring resistor measuring current through the coil. a two-point control circuit switches a first switching element on or off depending on the measured current through the coil to keep the average current through the led arrangement constant. a current amplifier circuit connected to the current measuring resistor detects current flowing through it and, by superimposing an offset voltage applied to one of the inputs thereof by an offset voltage source, can measure both positive and negative current. the output terminal thereof is connected to the input terminals of the two-position control circuit. the offset voltage is superimposed on the threshold voltages thereof. a starting pulse circuit is provided, and connected via a diode to the control input of the first switching element.

Inventor(s): Emil Kovatchev

CPC Classification: H05B45/327 (Burst dimming)

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