Luxeon I slug electrically neutral or not?!

I carried out a little test abt white Ryoj LuxI slug neutrality: First I connected Lux I to 2 AA liths through an ampmeter so that I could see the current all the time. For a benchmark I left first the slug non-connected. Then, keeping the circuit otherwise the same, I connected the slug directly to the anode: no change in current consumption. After that I connected cathode to slug and again no change in current consumption.

Now I'm wondering what should I think abt LuxI slug neutrality. According to the LuxI datasheet and several posts in CPF the slug is non-neutral and should be isolated. However, my test shows the opposite. Can someone please tell me what I'm missing here? /ubbthreads/images/graemlins/thinking.gif

- Nereus

It is not neutral. There are two reverse-connected ESD protection diodes, one from the slug to each power lead. If you were to apply a high enough voltage from slug (+) to either lead (-), you would forward bias one of those diodes, and cause a large amount of current to flow through the diode, bond wire, and power lead, possibly fusing the bond wire.

For the most part, for white/green/blue Luxeons, you can get away (in a sense) with not isolating the slug.

But, on red/amber/r-o luxeons, you MUST isolate the slug. It is DIRECTLY connected to the + power terminal, and if you connect the slug to "-" while powered up, you will short the power source through the positive bond wire, and fuse it open.

It is absolutely imperative that for those luxeons, that the slug be isolated.