Patent ID: 6538393
Filing Date: 2003-03-25
Classification: H05B

Abstract:
A circuit arrangement for supplying a lamp, provided withinput terminals for connection to a supply voltage source, a first circuit portion I for generating a current through the lamp from the supply voltage delivered by the supply voltage source, a digital control loop controlling an operational parameter to a desired value, provided with a sample circuit portion for sampling a actual value of the operational parameter with a predetermined frequency f, a control circuit portion for generating a control signal whose most recent value is Un, provided with an integrating circuit portion for augmenting Unâˆ’1 with K*En, with Unâˆ’1, being the most recent value but one of the control signal, En being the most recent value of an error signal which is a measure for the actual value of the operational parameter minus a desired value of the operational parameter, and K being a proportionality factor, a second circuit portion II for influencing the value of the proportionality factor K, provided with a memory for storing the most recent value En of the error signal and a most recent value but one Enâˆ’1 of the error signal, a comparator for determining a sign of each of the values of the error signal En and Enâˆ’1, a circuit portion III for increasing the proportionality factor K if the values En and Enâˆ’1 have the same sign, and a circuit portion IV for reducing the proportionality factor K if the values En and Enâˆ’1 have unequal signs.