It’s a 15mm boost driver, potentially intended for 1xAA, 2xAA, and 1xCR123A applications. I have only a limited idea what hosts it fits in though. I was hoping other people would chime in on that, I have very few of those types of light.
Maybe Ultrafire C3 and SK68. Also take a look at comments in my recent 15mm DD+7135 driver thread maybe? [WIP] *15mm* DD+single-7135 driver - single sided Dual-PWM compatible using 3.3x3.3mm FET
I have made some prototypes with 7mm inductor, linear moonlight, voltage monitoring and ramp programmable modes (I don’t have the linear ML and VM programmed in my firmware yet). The problem is that I don’t have enough time to play with it. I need to make one more version with more space for diode so maybe I’ll end with just 5mm inductor. My previous versions used small diode and it didn’t perform very well. I also made a nice board for ATTiny10 but I realized that it doesn’t have an eeprom too late :-/ I have some useless boards now.
ATTiny10 version (quite useless)
Nice! 15mm drivers open up the possibility of modding most AA-sized lights.
And if it is all going to work: will this driver have:
a) a decent efficiency compared to other boost drivers
b) a decent output current on a 1.2V NiMh battery, like over 1A through a XP-G2 emitter ?
In other words, apart from being able to have a custom UI (which is a wonderful perspective in a boost driver!
), does it also outperform the middle-of-the-road boost drivers that come with cheapie lights?
Ah... I was under the impression its only for lithium cells!
so it can run of AA cells as well? thats great
Don’t get too excited djozz! The PAM2803 is only the normal boost controller we find on common boards such as DQG AA/AAA lights, Fenix E05 (& probably others), DX SKU#128084, Nanjg-110, and many others.
The answers to your questions are “maybe” and “no”. No, it will not put out 1A from a single NiMH. The datasheet has a good and easy to understand graph on that subject, please take a look. Efficiency? I expect that to be similar to other similar drivers such as the ones mentioned above. Take a look here for HKJ’s review of the 400mA Nanjg-110. It is not very efficient: no surprise!
No comment on running it with lithium cells. It is a boost controller with a cap of around 5v for output and a minimum of around 0.9v (startup) voltage for the input. It’s intended for applications where input voltage is lower than LED Vf. Generally speaking that means that it is intended for driving white LEDs on 1xAA, 2xAA, or possibly 1xCR123A.
But the first of its kind where you can flash your own firmware! On an AA driver!?
Well, not the first to be created: driveX’s driver seems to be dated 10/14. 
But yes, mine may end up being the first publicly available one where you can flash your own firmware.
Am I right in thinking that Pin5 (VOUT) is simply a voltage feedback pin?
The pin descriptions in the datasheet are not very useful. We’ve already got other pins for Switch and FB/SENSE, so I can’t imagine VOUT being anything but voltage monitoring…
Sure it should be a feedback for oscillator. It’s 5am now and I’m having finals at nine so I will get back to you later. Tomorrow probably, after getting some sleep 
Thanks driveX. I have updated my layout. For now I have assumed that VIN can have a small trace. Please let me know if you think that this is incorrect.
Good luck w/ your finals!
v016
What would happen if the driver was built with a high resistance sense resistor for a current a bit above the requirements of the drive and a barely glowing LED AND a FET in parrell with the sense resistor so to increase the output, the micro controller would have the FET turn on? I’m not sure that the PAM2805 will take kindly to this kind of treatment or if it would actually do anything for efficiency on lower modes.
I’m not really sure where you’re attempting to go with that line of thinking.
With weak cells or 1xAA you’d get the normal current for 1xAA. It’s not limited by sense resistance at low input voltages.
With 2xAA and strong cells I assume you’d burn the PAM2805 when you turned on the FET.
H-man, I have to completely agree with Alex here the circuit in the boards above is the correct use of this boost iC, can you link to a datasheet your looking at or why it is exactly you think adding those components would do anything different / better?
Can we back up (probably a topic for its own thread) but what is it your trying to do? Just have a higher current boost driver?
Don’t FETs of the size being used has an on resistance similar to that of the feedback resistor (~130 mOhm)?
The intent is to have the driver have a low mode without having it bounce off of the voltage limiter. My line of thinking is that with 2AA on lower modes, the PAM2805 would have to boost the voltage from ~2.4V to something below 3V with the FET off and then only have to boost to the relatively high voltage necessary to run the desired current through the LED when it is being pulsed. The current design has the PAM2805 bounceing off of the voltage limiter when the FET is off, right? That can’t be terribly efficient.
RE: The PAM2805 burning up: I shorted out the sense resistor on a boost driver that looks to be built around a PAM2805 or similar, it did not burn. There may have been some resistance in the circuit, but bypassing the sense resistor bumped current being pulled off of 2 eneloops from 1A to nearly 2A.
Has anyone prototyped this circuit? The basic PAM2803 circuit can be harvested from this cheap driver. Actually, that driver can be connected to any BLF DD driver for prototyping.
Can it be filed to fit a 14mm cavity? I wanted to put one in a brass AA light from Cnq / Banggood.
IIRC I haven’t actually shared this driver yet. I haven’t ordered or built any. Thanks for linking to a cheap donor driver for the parts. Now I’m somewhat more interested!
Maybe if you are very careful. You’ll probably break the GND ring on top and have to rely on the GND ring on the bottom for continuity between the GND vias. I thought that those lights used a 15mm driver?
Hmm, I see what you were going for now. Personally I still think it’s a bad idea. The on-resistance is not a static value, or even “near static” like a passive resistor’s value (which does still change with temperature). On-resistance changes significantly based on both input voltage and load. Unless someone spells it out for me that this idea will reliably function, I am going to assume that it will not reliably function. 
Ah, now I see that you’ve actually done an experiment.
Interesting. In that case, maybe the idea is viable. I still think that it will be prone to burning things. If the PAM280x doesn’t burn instantly it can still burn over time. Of course the next question is also whether anyone actually wants a 2-mode 1xAA / 2xAA driver? (I’m asking, not telling.)
As far as the bouncing off the voltage limiter business… I wouldn’t worry about it. These things have terrible efficiency in all cases I’m pretty sure…
If you PWM the FET, you can still use PWM in theory (in reality, it may fail hilariously.) I’ve tested a shorting of the sense resistor, I haven’t tested long enough to trust it but if the efficiency is still horrible, that point is moot because the whole point of this would be to try to improve efficiency. Are there no efficent boost ICs?
BACK ON TOPIC: At this point, just being available will make this the best boost diver for multimode AA/2AA lights because I don’t think there is a single microcontroller driven boost driver for AA/2AA/CR123 on the market right now.
Would there be any benefit to using a remote mounted toroid choke in this driver?
There are plenty of efficient boost ICs, but not with a 1.2v or 2.4v Vinput.
If nobody sees any problems with this driver as laid out in post #13 then I’ll review for design rule violations and release it as a WIP.