Other than Led4power and stacking chips on a 7135, are there any other regulated 17mm 1S 5A drivers available?
A 7135 slave board in the bottom of the driver cavity or piggybacked is also an option rather than stacking them.
There are boards larger than 17mm that have enough 7135’s on them, like wights 22mm driver, which mtn presently sells.
DD fet.
Oops, I updated it. Had to be 17mm. Unfortunately, not much room in driver cavity.
Actually can’t do DD on this light. Has to be regulated.
When do you need it? I might have something that would work but the firmware for these drivers is not finished. I have a giveaway going with them but it’s taking time: Driver giveaway: Constant current 17mm drivers, winners (finally) announced, post #2.
The Slim4 goes up to 4.5 amps if sticking within regulator specs, but I have noticed that these regulators can be slightly over-driven. Over-driving the 3 x 1 amp regulators to 1.2 amps each would get you up to 5 amps. I have not done any over-drive testing though, so I can’t yet say how well they’ll hold up in the long run. Enter the giveaway by posting what your optimal firmware looks like. If you win I’ll build one for 5 amps and you can be the over-drive tester.
I would recommend modding this driver up to 4-5A:
http://kaidomain.com/S028155-New-LD-25-17mm-3_0V-4_5V-3A-4-Mode-Driver-Circuit-Board
You just need to heatsink the linear regulator, and you will be good to go.
I assume the 5A driver is for the 1mm white flat?
What about a 7-8A driver for the 2mm white flat?
Mike C, you seem to be using some higher current linear constant current chips, sort of like bigger 7135 chips? Would you share how these work or other good options for higher current versions of the 7135?
I’m using CN5710 (1A) and CN5711 (1.5A), using a digipot to adjust current. However, they are not compatible with 7135 design drivers (high side vs low side). There is more info in that giveaway thread: Driver giveaway: Constant current 17mm drivers, winners (finally) announced, post #2.
how to do that? it’s interesting
Yes. 5A for 1mm white. No interest in the 2mm as the 1mm will throw further.
Thanks, I did read about those. By chance do you know of low side higher current chips?
I’m also interested in how to mod the LD25 and how high it can go.
I’ve used CAT4104s, but I’ve found that the TDFN package 4104s tend to go into overheat shutdown pretty fast with freshly charged cell and LED with lower VF. Fairly annoying when some of them are blinking. The SOIC package seems to handle that better, but they are much bigger. The TDFN size was what got me interested in them. They are expensive too.
Just doing some brainstorming. Would it work to make a “slave board” of 1A CN5710 chips and add it to the high side of the LED, while keeping the rest of the traditional FET+1 circuit intact? If it works the way I think the max pulse current would then be set by the CN5710 chips and the FET would then modulate by pulsing that current, and the 7135 would still work for the low modes.
Would be similar to stacking a bunch of 7135 chips but the 1A chip setup would be more compact.
Well, it would probably work but the low modes would be horribly inefficient because first you have voltage drop over the CN5710s, then voltage drop over the 7135s.
Cool I might buy some to play around. For the low modes wouldn’t the total voltage drop to get to 350mA be the same? Just some of the drop would be over the CN5710s and the rest across the 7135?
The regulators dropout voltage is over the actual regulators. Having a 7135 in series with a 5710 won’t make the drop over the 5710 smaller. The GND of the 5710 will be going to the 7135, you can’t just make the drop smaller by putting another type of regulator in series. Same with the 7135. It can’t tell weather the current has passed through a 5710 or not, it’s voltage drop will be the same as if the 5710 wasn’t there. You will have two voltage drops in series. I don’t see any way around that… But stuff like this can be fun testing, just give it a go and see what happens!
I just ordered some from DHgate. I couldn’t find them at mouser or digikey or anywhere else.
I think I see what you’re saying about the dropout voltage. The additional dropout voltage would mean the light would drop out of the 350mA regulation sooner, but still not until ~3.2V cell voltage for the 2mm white flat. But until then as long as the LED is getting the 350mA I don’t see how the efficiency could be lower.
It wouldn’t have the nice PWM-less dimming like your drivers, but it could be a neat add-on solution for FET drivers and the very low Vf LEDs.
Well, I was thinking that if you have current flowing through two regulators in series you will have two regulators burning off power as heat. They have power dissipation according to this formula: Power dissipation＝ Voltage drop * Current. If you have two regulators burning off heat you have twice as much power lost, twice as inefficient.
But on the other hand maybe it’s the same as having multiple 7135s in parallel, they all dissipate power too. If they aren’t dissipating power they aren’t doing anything. So yeah, maybe it’s not as bad as I thought in terms of efficiency.