I’m looking at buying SST-40’s from KD and as one of the great uneducated masses I’m a little confused about voltage bins.
VH 2.5-2.7V
VJ 2.7-2.9V
VK 2.9-3.1V
I’ll be experimenting with some different drivers but for starters I’m looking at this one 2.8A single mode.
This states output 3V - 3.6V.
My question is will any of the Voltage Bins work with this driver?
It seems like even the VK bin is still potentially going to be overvolted by the driver.
To add to the problem the VK voltage bin are only available in N4 flux bin & 8000-10000K at KD.
The VH voltage bin is available in N5 flux bin & 6500K which would be better, but only if they don’t blow up immediately!
I’m guessing (my electronics skills are minimal!) that this driver uses a sense resistor somewhere to control the output voltage. Presumably it might be possible to change that resistor to achieve the desired output voltage, but I don’t really want to get into that and I’m not sure my soldering skills are up to doing SMD work anyway. And that doesn’t help me much if I want to try other drivers.
I’m also wondering about trying this 4.5A XHP70 6V driver with two SST-40’s in series. Again, my ignorance makes me unsure if this would work, and if the Voltage Bin is critical.
Generally speaking, Vf bins are not very important for current-regulated switching drivers.
They’re important mostly just for direct drive lights, because a lower Vf means more current through the LED.
A too-low Vf with an emitter that doesn’t tolerate overcurrent in a FET light can result in a broken light, for example using the wrong hex file with a Wurkkos TS10 of the newest batch.
Also, why specifically SST-40? It is not very popular now, consider the SFT-40, it has better tint and higher intensity.
Thanks.
Just for my understanding, is it not so important because the driver is controlling the current, and therefore if the current goes up it lowers the voltage? In simplistic terms for the electronically barely literate.
I went toward the SST-40 because:
a. I don’t care much about tint - it just has to create plenty of light. It’s for a visibility flasher. In some ways a slightly green tint would be an advantage as our eyes are slightly more sensitive to greens. Canopy Flasher
b. At least at KD the SST is half the price of the SFT.
LED prices on KD are very inflated, I recommend buying them from convoylight.com
The LED I would recommend for that use would be an XHP50.2, they are very efficient and very bright, it is what DJI uses as the beacon LEDs in their professional series of drones. It’s available in a nominally 3v (1 die in series) and 6v (2 dies in series) configuration.
A higher current means the voltage goes up. The current bin is basically just moving the current/voltage curve up or down.
I’d assume that driver is probably regulated in constant-current mode, so it probably doesn’t matter regardless.
If you’re actually using a 12v system though, I would recommend using them wired in 2S so that you can use current regulators that take 12v and output approximately 12v, similarly to automotive LED highway lights.
I’m not too sure what you’re saying here.
Wouldn’t 12v output totally fry 2x 3V LED’s in series? I’d have thought I’d need to run 4x LED’s in series?
I think you’re saying that I could just use any 12v current regulator of my desired output current? Not bother about looking at specific LED drivers, just find a suitable regulator? Makes sense I think. But I’m still a little confused about the voltage requirements out of the regulator vs the number of LED’s in series.
EDIT: Is this the sort of thing you’re suggesting to drive the LED’s with? LM2596 adjustable regulator
I’ll have to think about how I then generate the strobe pulses.
There are 6v versions of the XHP50.2, which is why I recommended it. They each have 4 dies, and depending on the variant they are configued as 1S, 2S or 4S.