Thanks for that write up Barkuti, I need to read it a couple more times to understand all of it. I wasn’t familiar with Ohm’s Law so I was scratching my head wondering what the letter “I” meant until I input that formula into google haha.
The CULPM1 leds are from Convoy. I have been using the 7A ramping driver as I’m unsure how good it is to drive them with that 8A driver. There’s no tint shift at 8A so that’s a good sign anyway.
Top three were in the L21A, bottom one in the C8+ , the only difference in the setup is the L21A tail switch. It’s a fet driver so I do understand it’s not going to be the same across all leds but should it be that much? I’ve never had it vary so much on other models using the same springs and batteries
In that case I think there are a bit too many variables to get more than a rough average which I think you succeeded in. Certainly not enough precision to worry about reflow though.
Unless you use a power supply and heavy duty heatsink combined with more consistent measure like bare LED using lux not lumens. This is why djozz and others get so burnt out doing it. That level of detail necessary is a pain in the butt.
As far as I understand, what is considered a (MOS)FET driver is a sort of very simple driver basically consisting of a switch and an MCU. These drivers are unregulated and the only way to obtain modes with them is to use the dreaded PWM (pulse width modulation). To attain regulation the flow of current must be sensed, this is done in a current sense resistor, usually a big sized, ultra-low value resistor in the periphery of the driver board:
A 1206 imperial R005 in this one.
So, technically speaking this is not a “FET” driver. These drivers are regulated, they make use of the voltage they sense via their sense resistor to trigger events in their MCU, that is, they use such information to drive the MOSFET gate so the required amount of current goes through the sense resistor (i.e. they open the switch “just enough”).
Ah, okay. I appreciate the correction. I struggle quite a bit to understand how components work when it’s something new in writing, I learn best visually.
Now I realize that the driver I’m after is one that has stabilization, would that be constant current or something else? What we see usually on boost drivers.
Tom E, you may want to fix the nicknames back there: if the NM1 and PM1 are Wn, where n = die area in mm², then the Boost HL and HX which are their bigger footprint counterparts should be dubbed Wn.something, W1+ for the KW CULNM1.TG and W2+ for the KW CULPM1.TG, for example. You could also add some proper, simple surnames to the color variants for the sake of simplicity (just remember that the pure green is the phosphor converted green, with some CRI, despite being listed with a narrow frequency window versus the true green).
It’s a small indutance value of 0.47uH, the smaller the inductance the smaller the DCR usually, which is another reason you want a small inductance value in such small place, to actually minimize DCR at high currents.
Still it is small inductor, low profile, I cannot imagine constant current at 8A, for lower currents like 3A surely no problems. I would like to see a review with a flashlight, without artificial active cooling.
Otherwise it seems to look good for example appears like a couple of external FETs rather than integrated into the switching IC.
Don't think it's the best, but thought Hank was following other conventions.
I'm keeping this is a Word docx file for now. Will make it public when it's more finalized. I've learned a few things since putting this together. The different flavors always had me confused somewhat. For white, looks like the Boost HL and Boost HX are making the old W1 and W2's obsolete, except for the pricing.
In all honesty, I find hardly believable that going from 3030 to 4040 footprint can provide much of a performance gain for emitters so small die size wise. And mind you, there are 0 actual tests of the 4040 emitters; just a lot of gossip. A good emitter bin can make a much bigger difference in practice.
In any case let me tell you these are being sold fairly expensive right now, in my opinion of course. And you know why.
Gossip? Hank has #'s for his K1. I received yesterday 2 K1 drivers and 1 Boost HL on a 32 mm 4040 MCPCB. Not sure yet where it's gonna go though - think'n of a BOSS1 (100 mm head diam reflector light). I'm not setup or have the time for testing the LED though.