Gransee
Flashlight Enthusiast
GreenLED and some others asked about this. This has been posted before, but here it is again.
The Arc-AAA is partially current regulated. What does this mean?
Lets say we draw a line. On one end you have no regulation and the other perfect regulation.
<------------------------------------------------>
perfectly regulated----------------------------direct drive
Regulation means the light will maintain a constant level of whatever is being regulated (voltage, current, light, etc). Perfect regulation doesn't happen. All regulators have at least a small amount of deviation. A tight regulation system will not produce any visible drop in light output. That is to the human eye. This means without using any special equipment.
Another big advantage to using regulation is that it can protect the LED from damage by limiting the heating of the LED. This can be done by setting the regulation level where the LED won't overheat in normal use. Not all regulators are set for this however. I have seen nicely regulated systems merily burning up the LED. It is up to the designer to take in account how hot the LED is going to get, etc.
The most common type of regulation for LEDs is current regulation. This does improve the consistency in the light output but it is not perfectly flat. The efficacy of the LED changes with temperature so current regulated lights often have a droop in output in the first 5 minutes. There are also other factors such as heating effects on the regulator accuracy, noise effects on the feedback system, etc.
Another common form of regulation is voltage regulation. However, is not recommended for LEDs since the vf of LEDs changes quite a bit. Even for a particular unit, the vf will change with temperature, age, etc. It is also more difficult to produce a consistency from multiple units on a production line when voltage regulation is used. A competitor of ours found this out.
Regulation is generally a good thing but there are some disadvantages. there is the cost of course but you also can loose some brightness. how is this? On some systems, the LED can do more but the driver is holding back. To regulate, the driver needs to keep something in reserve so it can compensate for a gradual drop in input power.
With the Arc-AAA, size was the first concern. Other goals included sufficient brightness, some sort of regulation to maintain a decent consistency in output from unit to unit and from fresh to dead battery. Like I said before, its not perfect, but it does address the goals fairly well.
from an earlier post:
Partial current regulation means that the regulation is not a perfect flat line. Most regulators can keep the output within say +-2%, which is pretty flat. The Arc-AAA regulator is not as flat as normal regulators. But it doesn't follow the battery discharge either. So the brightness maintains better than a direct drive system. That is an important feature so we mention it. I call it partial regulation because some engineer-types might expect a more flat discharge if I just said "regulated". I have written quite a bit about why I didn't go with a flatter discharge in the Arc-AAA (check out the Arc-XRT for an example of an AAA with a flatter discharge that didn't go over well). I call it current regulation because it is the current of the LED that the feedback system most effects. This is done via the internal inductor current limit. Yes, I know the chip used is a voltage regulator trimmed for 5volts with no load (people who fancy themselves as technically knowledgeable discover this from time to time and point it out to me like I don't know about it). However, the way it is used in the Arc-AAA is unconventional. People eventually figure this out the more they look at it.
the proof of the existence of regulation in the arc-aaa is in the runtime graphs. it does not follow the direct discharge of the LED/battery combination. the proof that it is current and not voltage is that well first, the regulator never reaches its voltage set point (usefull for protecting the circuit from an open LED) but second, the same circuit is used in all the arc-aaa from IR to UV with vfs from ~2 to 4 volts without modication and without a big change in the run time. Yes, you might be tempted to say that its actually limiting (or even regulating) the input current and not the LED current and therefore it always draws the same amount of current for a given battery voltage and the LED current varies more. That is almost correct but the LED current tends to affect the battery voltage so things are not as simple as they appear. But it all works. I call it my little bumble bee (people used to say bees shouldn't be able to fly). And of course it is not super precise but it does meet the design goals nicely.
over the years, I have designed, prototyped and tested various new circuits for the arc-aaa. Some had greater efficiency or a flatter discharge. But they also had disadvantages, which I won't go into because my competitors need to do their own work. I have no doubt that people can make a brighter AAA. but I have yet to see an AAA that meets my goals more closely. I wouldn't be too suprised if someone did, there are lots of smart people around. I am just saying it hasn't been done before. Usually when people have a beef with the design of the AAA, its usually a beef with my goals and not how I met them.
Any rate, I do appreciate suggestions. It also warms my heart when people use the search function, but I understand it is human nature not to. So it is a bonus in my opinion. When I visit new forums I don't alway search either. This post will also eventually drop below the radar. it is the nature of the beast.
So hopefully this addresses some people's curiosity on the subject for the time being.
peter
The Arc-AAA is partially current regulated. What does this mean?
Lets say we draw a line. On one end you have no regulation and the other perfect regulation.
<------------------------------------------------>
perfectly regulated----------------------------direct drive
Regulation means the light will maintain a constant level of whatever is being regulated (voltage, current, light, etc). Perfect regulation doesn't happen. All regulators have at least a small amount of deviation. A tight regulation system will not produce any visible drop in light output. That is to the human eye. This means without using any special equipment.
Another big advantage to using regulation is that it can protect the LED from damage by limiting the heating of the LED. This can be done by setting the regulation level where the LED won't overheat in normal use. Not all regulators are set for this however. I have seen nicely regulated systems merily burning up the LED. It is up to the designer to take in account how hot the LED is going to get, etc.
The most common type of regulation for LEDs is current regulation. This does improve the consistency in the light output but it is not perfectly flat. The efficacy of the LED changes with temperature so current regulated lights often have a droop in output in the first 5 minutes. There are also other factors such as heating effects on the regulator accuracy, noise effects on the feedback system, etc.
Another common form of regulation is voltage regulation. However, is not recommended for LEDs since the vf of LEDs changes quite a bit. Even for a particular unit, the vf will change with temperature, age, etc. It is also more difficult to produce a consistency from multiple units on a production line when voltage regulation is used. A competitor of ours found this out.
Regulation is generally a good thing but there are some disadvantages. there is the cost of course but you also can loose some brightness. how is this? On some systems, the LED can do more but the driver is holding back. To regulate, the driver needs to keep something in reserve so it can compensate for a gradual drop in input power.
With the Arc-AAA, size was the first concern. Other goals included sufficient brightness, some sort of regulation to maintain a decent consistency in output from unit to unit and from fresh to dead battery. Like I said before, its not perfect, but it does address the goals fairly well.
from an earlier post:
Partial current regulation means that the regulation is not a perfect flat line. Most regulators can keep the output within say +-2%, which is pretty flat. The Arc-AAA regulator is not as flat as normal regulators. But it doesn't follow the battery discharge either. So the brightness maintains better than a direct drive system. That is an important feature so we mention it. I call it partial regulation because some engineer-types might expect a more flat discharge if I just said "regulated". I have written quite a bit about why I didn't go with a flatter discharge in the Arc-AAA (check out the Arc-XRT for an example of an AAA with a flatter discharge that didn't go over well). I call it current regulation because it is the current of the LED that the feedback system most effects. This is done via the internal inductor current limit. Yes, I know the chip used is a voltage regulator trimmed for 5volts with no load (people who fancy themselves as technically knowledgeable discover this from time to time and point it out to me like I don't know about it). However, the way it is used in the Arc-AAA is unconventional. People eventually figure this out the more they look at it.
the proof of the existence of regulation in the arc-aaa is in the runtime graphs. it does not follow the direct discharge of the LED/battery combination. the proof that it is current and not voltage is that well first, the regulator never reaches its voltage set point (usefull for protecting the circuit from an open LED) but second, the same circuit is used in all the arc-aaa from IR to UV with vfs from ~2 to 4 volts without modication and without a big change in the run time. Yes, you might be tempted to say that its actually limiting (or even regulating) the input current and not the LED current and therefore it always draws the same amount of current for a given battery voltage and the LED current varies more. That is almost correct but the LED current tends to affect the battery voltage so things are not as simple as they appear. But it all works. I call it my little bumble bee (people used to say bees shouldn't be able to fly). And of course it is not super precise but it does meet the design goals nicely.
over the years, I have designed, prototyped and tested various new circuits for the arc-aaa. Some had greater efficiency or a flatter discharge. But they also had disadvantages, which I won't go into because my competitors need to do their own work. I have no doubt that people can make a brighter AAA. but I have yet to see an AAA that meets my goals more closely. I wouldn't be too suprised if someone did, there are lots of smart people around. I am just saying it hasn't been done before. Usually when people have a beef with the design of the AAA, its usually a beef with my goals and not how I met them.
Any rate, I do appreciate suggestions. It also warms my heart when people use the search function, but I understand it is human nature not to. So it is a bonus in my opinion. When I visit new forums I don't alway search either. This post will also eventually drop below the radar. it is the nature of the beast.
So hopefully this addresses some people's curiosity on the subject for the time being.
peter
Last edited:
