Light emitting diode driving circuit

摘要

A light emitting diode driving circuit includes connected driving units, each of which is configured for driving multiple channels of light emitting diodes generating a feedback voltage for the corresponding driving unit. Each of the driving units includes a selection circuit for comparing the feedback voltage with an input voltage to output a smaller one of the feedback voltage and the input voltage to a next one of the driving units, as the input voltage for the next one of the driving units.

主权项

1. A light emitting diode driving circuit comprising a plurality of connected driving units, each of the driving units configured for driving multiple channels of light emitting diodes generating a feedback voltage, each of the driving units comprising:
a first comparator comprising a first input to couple to the feedback voltage and a second input for selectively receiving an input voltage and a power voltage; a pull-up switch coupled between the second input of the first comparator and the power voltage and enabled such that the second input of the first comparator is pulled up to the power voltage; a second comparator comprising a third input to couple to a reference voltage and a fourth input to couple to the input voltage and generating a selection signal to enable the pull-up switch when the input voltage is smaller than the reference voltage; a first output switch for receiving the feedback voltage and enabled by an output of the first comparator when the voltage at the first input is smaller than the voltage at the second input, to output the feedback voltage to a next one of the driving units, as the input voltage for the next one of the driving units; and a second output switch for operatively receiving the input voltage and enabled by the output of the first comparator when the voltage at the first input is larger than the voltage at the second input, to output the input voltage to the next one of the driving units, as the input voltage for the next one of the driving units.