Watt's the wattage when used on a PIC?

[ERMEGM]

That is the exact setup I have. I am using the ILD205 instead for the opto and the LS4148 for the reverse polarity protection. I have a diode on the positive input as well. The design of the board and wires prevents a reverse polarity connection. These optos are failing right out of the packaging. A bad batch? Maybe, but nonetheless, very time consuming to repair. Either way, if the opto fails, or the resistor fails, blowing the pic, the board is coming back to me.

At this point, my time is worth more than the cost of the pic or opto. I designed it this way because of the features of the opto, however, I've seen the other setup work time and time again without any problems. I was going to add the cap and Zener to boost up the protection a little bit on the VD setup. I'm not looking for cheap. I am more interested in reliability. The opto served me well until this last batch. Now I'm skeptical.

[MichelJasmin]

FIY, this is how our GPS units are designed:



On the "ignition" input the TVS is a big 1.5KE33 and none of the ~480 units failed me. The other "conventionnal" I/O are either "ground inputs" (the ones that fails often) or optoisolated. I had a few units who failed on those opto inputs but the TVS is a 0805 SMT. If I came across a failed one I'll do an autopsy to find out what failed...

HTH