Texas Instruments Incorporated Deutschland, Gmbh

Texas Instruments Corporation

Helmut Kiml

Hans Schmeller

Christophe Vaucourt

Harald Sandner

Martin Rommel

A method is provided for driving a plurality of light emitters in a plurality of output paths with each output path including at least one light emitter. The method includes the steps of applying a supply voltage level to a plurality of output paths; generating a current for each path during a period of a predetermined length for the output path; sensing a current level for each output path during the period; comparing each sensed current level with a reference level; increasing the supply voltage level if the sensed current level is lower than the reference level; determining a lowest supply voltage level for the worst case output path; and using the lower supply voltage level as a common supply voltage level for all output paths.

LED driver with adaptive algorithm for storage capacitor pre-charge

A method for driving a light-emitting semiconductor is provided. A supply voltage is converted into a secondary output voltage for supplying the light-emitting semiconductor with an output voltage. A level for the supply voltage at the beginning of a high current phase of the light-emitting semiconductor is sensed. A threshold voltage level for the supply voltage level is determined based on the sensed level. The high current phase with the light-emitting semiconductor is stated. The sensed level is continuously compared with the threshold voltage level, and an output current through the light-emitting semiconductor is controlled such that the sensed level does not drop below the threshold voltage level.

Adaptive algorithm for camera flash LED power control vs. battery impedance, state of discharge (SOD), aging, temperature effects

A bus signal detector for a signal transmitted via a bus (12) has an edge detector (14) which supplies a signal (S.sub.F1) indicating the occurrence of a signal edge (F1) when the voltage on the bus (12) suddenly changes by at least a predetermined relative threshold (.DELTA.U.sub.s) in relation to a reference voltage (V.sub.ref) continuously adapted to the quiescent voltage of the bus (.sub.12). An evaluating circuit following the edge detector (14) uses the signal (S.sub.F1) supplied by the edge detector (14) to produce an output signal indicating a bus signal.

Bus signal detector

A edge detector for the production of output signal in a manner dependent on positive and negative edges of a square wave signal comprises a differential amplifier with two base-coupled transistors (Q1, Q2). Each emitter of such transistors is connected via a constant current source (S1 and, respectively, S2) with a supply voltage line (10) and the emitter currents of the transistors are split up between two collectors, of which the first ones are connected with one another and, via a third constant current source (S3), with ground (12). Two output loops each comprise a series circuit composed of a resistor (R3, R4) and the collector-emitter path of an output transistor (Q3, Q4) between ground (12) and the supply voltage line (10). In the case of each of such output transistors (Q3, Q4) the base is connected in each case with a second collector of the base-coupled transistor (Q1, Q2) so that the switching state of the output transistors (Q1, Q2) is set by the voltage at each second collector. The output signals are able to be tapped at the collector of such output transistors (Q3, Q4). An input terminal (14) is connected with the emitter of one (Q1) of the base-coupled transistors (Q1, Q2) for the supply of a current dependent on the input signal and one capacitor (C1) is connected with the emitter of the other one (Q2) of the base-coupled transistors (Q1, Q2).

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Tiefenbach, Germany

Helmut Kiml