We’re talking about 1A output here, not more.
The PAM2803 is specified for 0.75A output. The Nanjg110 is overdriven already with a lower sense resistor (R100 instead of “R127”) and puts out ~1A in 2AA config. But this seems to be safe ground.
I have several Nanjg110 in household use (bunch of silver L2m with 1AA, 2AA in MiniMaglites) and none of them has died yet.
Any chance of paralleling 2 boost circuits on one pcb and controlling them with one attiny 13A?
I hooked up the full setup (110, ak47, FET) with 2AA and got magic smoke from the PAM2803 
The boost controller simply blew up. |(
It occured after one of the first mode changes, I’m not sure from which to which, it happened fast and unexpected to be honest. There seem to be some spikes…
It’s surely the controller that died, I just swapped this single component from a new 110 and everything is working again (with 1AA).
I’ll stick to 1AA for the moment unless anyone has a convincing idea what might be the cause and how to avoid this.
I found a nice diode for the job.
The stock SS14 is incredibly large while being not quite up to the job to boot (only rated for 1A while datasheet recommends 2A). As I looked for 2A diodes - all large as hell - I stumbled upon the BAT60A (datasheet).
Even rated 3A, only 370mV forward voltage, and SOD-323 package. It’s the teeny-tiny component on the right, where the cathode line uses up almost half the component. Oh, and the price… 10.5 ct.
I hooked it up in replacement and in the last days I drained 5x 1AA and 6x 2AA (Eneloops) on this driver, while monitoring input and output current. Works perfectly fine. Even increases output current in 1AA config and efficiency in 2AA config (needs a lower input current to reach the 920 mA). I’m truly impressed.
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^ Nice discovery. You're doing some real R&D. Thank you for reporting this.
EDIT: So far in my search pretty expensive with shipping. Best I've seen so far is on Ali for $1.06/each.
Wow, impressive indeed. So what’s the current parts list?
Boost converters in parallel to the same load don't work (unless they are the type that are meant to be synchronized).
Received my order of 50 BAT60A's yesterday. Won't have a chance to try them out until I wrap up my current project, but I'm excited about them. They're so small. Hard to believe they can handle 3 amps.
Thanks again for reporting your find HarleyQuin. :)
Thanks for the work on this driver guys, I do not have the background to be of any use but I sure would like to see this little 15mm boost driver come off the ground :-)
As djozz says. I appreciate the effort as well.
What about paralleling them with blocking diodes in series between each boost circuit and the LED?
+1 
A good strong boost driver so we can drive 6v led’s with a single battery instead of 2 shorter ones, is one of the few missing things in our ever expanding modding arsenal 
Any updates here?
This is worth a bump from the peanut gallery — just to see if anything shakes out.
At this rate, we’re going to need
a speed loader for batteries …
(with, of course, a supercapacitor to hold brightness while the dead cell is kicked out and the next cell is rotated into position …)
And so, bandoliers of batteries …
What about if only the outputs are in parallel but the internals are separate?
Maybe to a multi die led like mce or XHP where you can power one pair of die separate from the other. With the appropriate mcu different boost circuits could power each die of a color led but that’s a lot of circuit. In any case the advantage of small boost drivers is being able to run an led at low power from a primary cell for much longer than a recharge able li-ion whereas li-ions excel at shorter run, higher current applications. Trying to get enough current from a single alkaline to drive an led hard is like trying to carry a piano up a ladder backwards.
Could 2 pam2803’s be controlled by the at tiny to give two modes each with constant current rather than pwm control of an fet? Would need separate Rsense for each or maybe an ic switch to control separate Rsense only?
Good question RBD. Here are my initial thoughts:
- I barely remember how this works. Let’s see. The MCU runs off of the output from the boost circuit. That’s the weird and magical thing about these drivers IIRC. My memory of this simple circuit will need to be jostled, but that’s the first potential problem that springs to mind. We’ll have to think about this some more.
- Clearly two of these won’t fit into 15mm or course!
- Since you’re asking, am I to assume that nothing better has shown up? 1AA or 2AA boost circuits are still like hen’s teeth? Ugh….