Sample and hold method to achieve square-wave PWM current source for light emitting diode arrays
An apparatus for controlling overshoots in the switching of LED arrays in a system having a switching voltage converter providing the biasing voltage for the LED array. By synchronizing a switching converter to an LED turn-on signal, loading on the voltage converter can be controlled such that output conduction of the converter only occurs when LEDs that are to be displayed are switched on to provide loading to the output of the converter. A Sample and hold method is employed to effectively store the current information in a previous &#8220;on&#8221; interval and use it for the current control in a following interval with inhibited current overshoot.
Koninklijke Philips Electronics N.V.
H H Y H
H05B H05B Y02B H05B
inventional additional additional additional
Chin Bernd
Chang Clauberg