Mystery Prolight LED?

[Jeremy]

I've just bought a couple of star LEDs from Stellatus (led-bulbs.com). The ones I ordered were 3W PG1N-3Lxx Cool White, the ones from this link: http://www.led-bulbs.com/eShop/10Browsepro.asp?Category=3W .

The ones I received look just like the picture on the data sheet, which is here: http://www.led-bulbs.com/html/prolight/Low Profile/3W/Star/3W_PG1X-3LXS-SD_v2.8.pdf .

Now the mystery! I hooked them up to my current driver and they didn't work. I explored a bit further and discovered that they have a very high forward voltage, around 10.5 to 11V. Looking at them (when running at low current) it's clear that there are three LED chips under the encapsulant, which explains the high Vf if these are internally connected in series (3.5 x 3 = 10.5, pretty much what I'm measuring at the LED leads).

According to the datasheet, these 3W star LEDs are supposed to have a Vf of around 3.5V, which would work fine with the driver I have that runs from three cells (4.5V nominal). Assuming that these LEDs are OK for 700mA, yet have a Vf of 10.5, sort of implies that they are really rated at around 7 watts or so.

Anyway, the real puzzle is, what have I really got here?

Has anyone else had some funny Prolight LEDs that don't seem to match the datasheets?

Have I been lucky and really got some super high power LEDs for the price of the 3W ones, or are 3W LEDs always really three chips in series?

If anyone has a clue what's going on here I'd very much welcome some advice, as this sort of has me stumped at the moment!

Jeremy

PS: They were £3.75 each, or about $6

 

[Jeremy]

I think I've solved this mystery, but have to say that I'm less than impressed with the supplier.

According to the supplier (www.led-bulbs.com) the 3W Prolight and the 4W Prolight both have a similar Vf, around 3.5V. In fact, when I dug around and discovered the manufacturers website, www.prolightopto.com, I discovered that they make a 4W device that seems to be three dies in series, with a Vf of 10.5V and a If of 350mA.

It looks very much as if Stellatus (www.led-bulbs.com) have sent me the wrong LEDs. This is more than slightly annoying, because it's the second time they've got this order wrong. Before the holidays I ordered two white 3W LEDs, and they sent two RGD LEDs instead. I didn't bother to send them back, because I thought I could make use of the RGB LEDs at some point. Instead, I ordered two more 3W LEDs. This time they've sent me two 4W LEDs................

I may try again, and order a couple more, in the hope that I'll get what I actually need this time.

Sorry to take up bandwidth here, but my experience might possibly help someone else.

Jeremy