I am reworking a discrete driver design for a custom LED emitter device. While the driver can be changed, the custom emitter board currently cannot. It's designed for common V+ with multiple sinks, 10 groups of 21 LEDs in series. Our drive current would range from ~70mA to ~150mA.
We really like the ALED7709 and wanted to see if there was a way to cascade units to work with this custom LED circuit (three ALED7709s, one of which has two channels disabled). Obviously this is tricky concerning the voltage feedback circuit. As I expected, if I completely bypass VOUT and power the high side of the LEDs directly, control and dimming work but drive is lower than wanted. All lights will be dimmed/controlled in unison, so I was curious how bad the ALEDs would fight each other if I ran VOUT from one ALED, and tied all three feedback pins together.
