Hi, just one question because i read somewhere that driver with pwm is less effecient than pwm-less driver. Does it also mean that the pwm-less driver will also be brighter than pwm driver at the same current for example @ 0.4A?
We need more info about the PWM driver to be able to answer your question. What is the PWM drivers max current? .4A? Or more and you’re talking about running [say a 3A PWM based driver] at part current?
If the PWM driver maxes out at .4A then it’ll be full on (100% duty cycle, no PWM) and will have the same efficiency as a non-PWM driver at the same 400mAh, but if your talking about a higher current driver dimmed down (with PWM) to 400mAh vs a non PWM driver at the same current then yes, the non PWM driver will win out.
All this is assuming your talking about 2 LINEAR drivers. You can’t compare a linear to a buck or boost driver and expect the same efficiencys at like currents…
CK is right, they’re not really comparable. A pwm duty cycle is chosen to give a certain amount of light and a non pwm buck or boost driver supplies a (supposedly) constant current to give the chosen amount of light. A buck driver needs overhead(extra voltage) to maintain regulation and so might require 2 cells where a linear driver needs 1. Since pwm dimming is done using pulses of higher current the tint of a pwm driven led might not be the same as the same led driven from a constant current source. What certainly can be said is that a 100% duty cycle of 1A is more efficient than 50% of 2A but there is much more to it than that and you have to decide where you are going to compromise or what set up best fits your needs. Lots of drivers are available because no single one does everything equally well.
I am talking about my 2 drivers, ld-25 and a nanjg 105c. The 105c has 2x 7135 added to it for a total of 3.5A max and has a mode that gives 12% or 0.42A. The ld-25 is set to 3A maximum and mid to 0.4A using this video on how to adjust current of ld-25.
I just tested the two drivers using two identical blf x6 se. I measured the current at the tail, 0.39A for the ld25 and 0.45 for the 105c but I can see that the x6 with ld-25 is a bit brighter than the one with 105c.
It’s quite possible since the 105C is sending 3.5A pulses to the led and the LD-25 is constant current. DMM’s don’t always measure pwm current accurately so it’s hard to say for sure. You might try running each light from the same cell charged to the same voltage and compare run times.