20130049628 | Current-Switching LED Driver Using DAC to Ramp Bypass Currents to Accelerate Switching Speed and Reduce Ripple - A light-emitting diode (LED) driver provides faster rise and fall times for LED current to reduce image sticking and other interference. A standard DC-DC converter provides a sum current that is slowly ramped up and down by a bypass current digital-to-analog converter (DAC). A digital value to the bypass current DAC is ramped up or down before an LED current is turned on or off. When the LED current is turned on, current is shifted from a bypass path to a path through the LED, maintaining a constant sum current from the DC-DC converter. When a different LED is turned on, current is shifted from one LED's path to the other LED's path. Separate LED current DAC's in each LED path and in the bypass path can share the sum current with digital precision. Using a single DAC for the sum current and switches in each path reduces cost. | 02-28-2013 |