Gate for the FET on the left connects to Source by way of 20k of resistors. It’s those two series resistors marked 103 (10k Ohm) for a total of 20k. It appears that the PWM output from the MCU to the 5241 buck controller also has a 10k resistor connecting it to Source (marked 1002). I do not understand the purpose of this arrangement. When the PWM goes high the lefthand FET either becomes forward or reverse biased, but I am becoming confused. With my limited understanding I thought maybe that this was a hack to use the 5241 as a synchronous buck controller, but this does not appear to be the case.
-Side note: it may be fair to assume that the 5241a is just an even more generic 5241 than the others (LY5241, QX5241 and SM5241). Here is a listing on DinoDirect selling 5241a’s as “other brands” of QX5241… I think. oh, nevermind. Of course it’s just a generic QX5241, the a/b designation relates to feedback voltage. It’s right there in the QX5241’s datasheet.
No, it is not a boost driver. Output voltage will always be lower than input voltage. 2 series cells = max 8.4v, 3 series XML2 would require ~9.1v to run at 1 amp, ~10.3v for 3 amps.
Well to be accurate, yes it can be used with 2 cells, and yes it can be used with 3 series XML2s, but not both at the same time. 3 XML2s would require 3 or 4 cells. I guess you could use 4 18350s?
Not come to understand well … you say that for some series parallel combination?
About of the 18350 is a good idea! but I can not use where I want to install.
Input voltage must always be higher than output voltage with this driver, however you wire it up with whatever parts combo. To use 3 XML2s in series, the input voltage must be higher than the voltage needed to run 3 series XML2s. With only 2 cells you only have 8.4 volts input, but 3 series XML2s need more than 10 volts. That means you need more than 10 volts input, that means 3 or 4 cells (12.6 or 16.8v) input.
If you cannot change things around to get any more input voltage than 8.4v, you would have to wire the 3 XML2s in parallel, which would not be a good way to do it, since with LEDs in parallel the output current will be divided equally between them, that means it would only run at something like 1200mA per LED. If you wire them in series and raise the input voltage to 12.6 or 16.8v, the output will be 3.5A to all LEDs.
The most recent listing has slightly different specs: http://www.cnqualitygoods.com/goods.php?id=2123
As I mentioned, the early one I got didn't do anything different with the 'stars' bridged, it now has descriptions of what the stars do. Should be just a firmware change, the hardware is the same.
Group 1: 5modes by default (High/Mid/Low/Strobe/SOS) (no stars bridged)
Group 2: 5% 30% 100%
Group 3: 100% 30% Flash
Group 4: 100% 50%
Short-circuit two stars to change Group.
Before my time, but my understanding is that there was a light called Dry that had a driver that went into direct drive in the highest mode. When this driver became available separately, it became a very popular driver for mods. I'd like to know why this new "version" was called "Dry". It's so different in so many ways. Is there a new Dry light that uses this driver?
“DRY” is a name for this case, however the driver is not really physically dry or wet.
There was a flashlight called “DRY” back in few years ago, and Ric from CNQ has even organized a group buy for DRY in early 2012 in BLF and I bought one from there too (also the first GB I participated in BLF ). During that time there were not a lot of powerful multi-emitter flashlight and DRY was one of the highest lumens output LED flashlight available, putting out around 2500 OTF lumens was pretty impressive back then. The flashlight has good heatsinking (integrated) and the main point of this driver is allowing high current draw at turbo mode, it was claimed as direct-drive by the seller but it was actually still current regulated tested by somebody here.
And then there were several variations of this driver which I couldn’t remember the details. This year Ric has released the updated version of DRY flashlight, which is using this new larger diameter DRY driver. The older DRY driver was about 26mm (or a bit off), and the newer one is 32mm. According to CNQ website it seems that Ric has stopped selling the DRY driver separately, but the DRY flashlight is still available, though I’m not sure how is the quality and the driver inside.
To my understanding I think what comfychair trying to say is:
1. This driver accepts 2 cells in series - Correct
2. This driver can power 3 series XM-L2 - Correct
3. This driver can power 3 series XM-L2 with 2 cells in series - NO IT CAN’T (input voltage < required output voltage in this case, and a boost driver is needed for this job)
:_( …ok many thanks.
this I already had more or less clear…