Dear Sir,
We have implemented the upper ghosting circuitry proposed in tidu370 (line connected to a zener (common to all lines) through a resistor) and noticed that the Led Open Detection can't detect well our fail open LED, in particular red ones due to the lower forward voltage.
From our analysis, this is due to the current flowing through the OFF line LEDs that are all connected to the zener node with a 100 Ohm resistance, preventing the TLC59581 output node to go under the LOD detection level.
One of the solution is to have one zener per line, but it is not cost effective. Reducing the zener voltage level down to ~2.4V is also a possibility.
Is there any side effect from your experience if we bypass the zener and connect resistors directly to the ground?
Best regards,
Tristan
