| 摘要 |
A LED drive system for controlling an off-chip power supply enables the power supply function to be located 'off-chip'-i.e., on an IC which is separate from the IC containing the other LED drive system components. The off-chip supply provides a common line voltage for LED strings connected in series with respective current sink circuits at respective junctions, in response to a signal applied to a control input. The system includes a 'minimum' circuit which outputs the least of the voltages at the junctions, and an I/O pin which receives a signal that varies with the output of the minimum circuit. When the external supply's control input is coupled to the system's I/O pin, the present system controls the output of the external power supply as needed to provide a desired common line voltage. |
