Ah, that explains why on some boards I see the top copper layer actually extending beyond the milling layer…to compensate for that cutoff by the manufacturers…thank led4power, can’t wait to see these hit production!
Very interesting design, and I really like how you did the “stars” solder bridge locations…very cool!
I always made the copper bigger than milling because of laziness so I never had this problems…I also did some where the milling was in the middle of through holes(thought that would increase GND contact) and they milled perfectly through it.
Is this just a newer phenomenon from Oshpark, did I only had luck or was it the point that I made the copper ring bigger than milling the point?
Request for a run time comparison:
Same cell charged to same voltage
Match current output current between this driver and a Qlite 3A w/ one extra chip and pwm set to 1.1A.
Plot current vs voltage and time when each falls out of regulation.
Plot end of charge for both and calculate efficiency.
If you can get this driver up to 4A then add chips to a Qlite to match and then run the test.
That’s a good point… perhaps if someone does this test, it should be compared at the same lumen level instead of the same current?
(seems like the current would probably not be a very interesting test anyway, since any two devices at the same current will tend to have similar runtimes regardless of what they actually do with the power)
I wonder what the efficiency difference might be at 1.4A, or 1.5A, or 1.9A.
The 1.9A light I just put together with a Nichia 219B is really nice, and the PWM is fast enough it looks almost the same as full current control… but the runtime won’t be as long. I never really use it above 800mA or so (average), so I could reduce its overall power to increase efficiency, but it’s nice having a turbo mode once in a while. The higher power is also nice for strobes, because a 0.3ms pulse looks brighter at 1.9A than it would at 1.4A.
For a bike tail light, I went with 700mA because djozz’s measurements show that as more efficient than 350mA or 1050mA on a red XP-E2. I don’t need it that bright, but it should increase the overall runtime at the same brightness levels, even when using PWM.
The efficiency difference is because a 50% (or whatever) constant current requires a much lower Vf, compared to a PWM'ed 50% which is full current for half the time and none for half the time (assuming both drivers do the same current at 100%). The average current might be the same for both drivers but the voltage isn't and the total power used comes from both volts & amps.