I agree. I just chose the 7805 because I liked the way it fit the board. Long term I would do something to protect the mcu. The tests(Doh) that I ran showed the 7135’s to be better than the mcu at running this way.
It’s up to you. If you do you should only see about .2 mA there. The higher voltage might push more current though so it would be interesting to see just how much.
162 ua, so .162 ma.
That’s spot on. it’s probably less when running at 4V. This is promising for anyone looking to hack together a 2S linear driver. I think for a light to b put in reliable service, some sort of voltage regulator should be there to feed the MCU. A zener regulator is a resistor and a zener diode in series. Formula for the resistor value is here. I’ll guess that the MCU and 7135 chips need no more than 10mA to operate.
I am out of NANJG drivers at the moment. Once I have more in, I’ll see if there’s an easy way to mod them with a Zener regulator.
Thanks for taking the time to do this, Scaru. Your measurements seem all to be reasonable values so the test looks legitimate to me. Fwiw. I guess the next thing is for someone to try some longer term testing in an edc.
Not sure if it would be helpful, but I could hook this up to a power supply and leave it running for a while. (Days/Weeks)
Scaru, I think a day or two would be adequate.
I think it would be good to do it in medium output as well. All that PWM switching might stress things more, who knows.
I’d have this hooked up already if I had a loose driver kicking around. Wait, I’ll try one of the generic 7135 drivers…
I don't actually have a driver, just a bunch of chips. So how many chips should I do? I think just one is fine, mostly because that means I don't have to bother with a heatsink. ;)
OK, I got up to 7V before the driver got very hot. The MCU on these is not an ATTiny, and it’s the hottest component. It starts heating up before the 7135 chips begin to regulate. It doesn’t like over-voltage.
At 7V when regulation begins (just over 3A), the MCU was 85C and the 7135 chips were right behind at 78C or so.
I didn’t push it any further. No way you cold hold this driver between your fingers.
Scaru, check the heat on yours when on a power supply. I used an IR temperature probe, but anything over 60C is uncomfortable to touch for more than a second or two.
Just plugged it in to begin the test. :D I can test heat with a temperature probe, I will wait an hour or so and test it then.
Cool, hopefully 
Mine heated up in about 20 seconds at 7V… I think the ATTiny based driver might fare better. Fingers crossed.
I held off on doing this mod because of the lack of low voltage sensing but I could do up a 3 x 14250 - 3 x Nichia for testing. I still have a 1.4A board with a VR chip on it ready to go. I’d just need to make a 250 spacer.
You certainly could, I would hold off for a day or two to see whether it survives 24 hours straight.
I ran this test last summer with 3 x XML until the batteries were dead with no problems but I can wait. I’ll just get it set up.
I just finished the internals of a headlamp and wired linear driver to pair of spot leds in series.
We’ll see how it goes. Spot is of secondary importance.
It is currently still running perfectly fine so I'm discontinuing the tests. Now we just need to know whether the other components on the boards can withstand a higher voltage.
This is a great thread with great minds contributing. It still goes over my head in spots. I would like to try the mod in Post 22 above. I want to use it to drive an MG-T2 with 2 li-ions or 6 Ni-Mh’s. I’m not following the bit about adding a resister with a switch to cut it (the resistor) out at lower battery voltages. Would the resister part be necessary for my app which has fairly limited difference between supply voltage and Vf?
Secondly, wouldn’t the 2 volt dropout from the 78L05 serve as a low voltage cut off? 7 volts comes out to 3.5v for each cell.
Edit: I mistakenly posted here. Here is the original posting I was thinking about. I will post there. Please disregard this post as it seems the following thread is the more appropriate place for this question: