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sergio_pt said:
That's great george. Also love the idea of thermal dimming, I hate when the light goes OFF.
Thermal dimming has always been there, just need to test that it works correctly with threemode/trimode - so far it appears to be working correctly.

Now testing that the thermal dimming works correctly in the strobe modes - though it shouldn't ever overheat in when strobing.

cheers,
george.
 

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sergio_pt said:
So why is my maxflex shutting down when it gets hot? I think I should read the instructions.
It would shutdown if you are at the point of destroying the switcher IC, which means you have inadequate heatsinking or badly applied thermal paste. I've written a decent document regarding the thermal issues that need to be addressed and you can find it in the maxflex tech section on www.taskled.com

The switcher IC does NOT have thermal protection, when it overheats it goes into some strange mode where it sorta/kinda turns off, but I HIGHLY recommend you address the thermal path issues before you destroy the drive.

By default thermal monitoring is NOT enabled as the driver is shipped.

Yes, reading the manual can be helpful...

cheers,
george.
 

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OK, a new day, the sun is finally shining and the sky is all blue here (at this minute). Quite a wet phase that we've been dealing with in California - but we need the snowpack to thicken up for the summer months.

Anyhow, on to the important stuff. I've completed testing (on a bFlex) the new Threemode/Trimode additions and all looks good. Tested the normal mode, the strobe mode and thermal dimming in both and everything is operating correctly.

So, all that's left is updating all the *flex manuals to reflect these new changes and how to select them in the menu system.

I've just about completed the maxflex doc changes and then I'll cut/paste it into the bFlex/hipFlex and d2Flex manuals. All the new manuals will be online on the taskled website later today.

All flex drivers that ship from me as of Jan 25 2010 will incorporate the new firmware.

Maxflex5A driver are suppose to be shipped to me today - but they've already been delayed 1 week so as always, the proof of the pudding is in the eating or in this case the boards actually arriving in my hands...

cheers,
george.

p.s. thanks to all for the suggestions and comments regarding the operating modes most desired for UIB and hopefully the newly added Threemode and Trimode will make the majority of folk happy. These are the first major changes in over 2 years to the UI-uni firmware.
 

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troutie-mtb said:
Not to worry though as he did pre programme them for me and did away with the 5 level multi mode and replaced it with a hi/ med/ lo mode which I like lots ..:thumbsup:
Woo Hoo :D who would have thought the end result from a chance comment .

how many clicks now to set up a Flex driver :lol:
 

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georges80 said:
It would shutdown if you are at the point of destroying the switcher IC, which means you have inadequate heatsinking or badly applied thermal paste. I've written a decent document regarding the thermal issues that need to be addressed and you can find it in the maxflex tech section on www.taskled.com

The switcher IC does NOT have thermal protection, when it overheats it goes into some strange mode where it sorta/kinda turns off, but I HIGHLY recommend you address the thermal path issues before you destroy the drive.

By default thermal monitoring is NOT enabled as the driver is shipped.

Yes, reading the manual can be helpful...

cheers,
george.
I set the thermal protection for 60ºC and the light still shuts off. What is the temperature at which the switcher IC stops working? I didn't use heatsinking in the IC maybe that's the problem.
 

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georges80 said:
Yes, reading the manual can be helpful...

cheers,
george.
The thermal management white paper is a highly recommended read, too. I find both it and the manual a great help with my insomnia...:sleep:

Just kidding!

Superb job as always! Now I just may have to build another light to try the interface out!
 

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sergio_pt said:
I set the thermal protection for 60ºC and the light still shuts off. What is the temperature at which the switcher IC stops working? I didn't use heatsinking in the IC maybe that's the problem.
You have no heatsinking at all? If that's the case what do you expect... the switcher IC WILL overheat unless you're running pretty low current and minimal LEDs etc.

It's the junction temperature that's the issue - not the plastic case temperature. Anyhow, go read the manual AND the tech section AND the thermal white paper. Then you can ask some questions if the answers aren't in those 3 areas.

cheers,
george.
 

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Well in fact I remember reading all that boring stuff before I assemble everything.

And I remember reading this in the thermal guide:
"At power levels with driver heat losses in the 2W range, it is sufficient to utilize a single heatsink attached to the gold thermal attachment area. As heat losses increase beyond 2W it may be necessary to provide heatsinking of the inductor to prevent shutdown and possible damage of the switcher IC. "

After reading everything and this conclusion you make it sound like losses higher than 2W are the worst case scenario, and you make it sound like IC heatsinking is just optional. As a newbie I just skipped that heatsinking and made a very good thermal path for the golden rectangle thinking it was enough.
Indeed the driver works well at sub-maximum levels but at max it shuts down in a couple of minutes.
You don't have any information about the IC failure temperature, that could be important info for the light designs.

Anyway I'll try to get a way to heatsink the IC with everything assembled :rolleyes:

Good work with the programming.
 

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sergio_pt said:
Well in fact I remember reading all that boring stuff before I assemble everything.

And I remember reading this in the thermal guide:
"At power levels with driver heat losses in the 2W range, it is sufficient to utilize a single heatsink attached to the gold thermal attachment area. As heat losses increase beyond 2W it may be necessary to provide heatsinking of the inductor to prevent shutdown and possible damage of the switcher IC. "

After reading everything and this conclusion you make it sound like losses higher than 2W are the worst case scenario, and you make it sound like IC heatsinking is just optional. As a newbie I just skipped that heatsinking and made a very good thermal path for the golden rectangle thinking it was enough.
Indeed the driver works well at sub-maximum levels but at max it shuts down in a couple of minutes.
You don't have any information about the IC failure temperature, that could be important info for the light designs.

Anyway I'll try to get a way to heatsink the IC with everything assembled :rolleyes:

Good work with the programming.
The information to calculate the actual IC failure temperature doesn't exist in a useful format unless you have a LOT of extra information. The Absolute Max Junction temperature is specified as 150C. The datasheet shows the thermal resistance of the package to the thermal pad. But then it goes through the PCB material and that has its own thermal resistance, then you have the thermal paste/epoxy you used with its thermal resistance, then the aluminium or whatever you used and finally to the body of the light itself.

You still haven't told us How many Batteries, What Voltage (total), What Chemistry, How many LEDs, What drive current. With those numbers I can give you an idea of how many watts dissipation will be due to efficiency losses.

The thermal monitoring will NOT be able to catch a bad heatsink attachment to the gold area of the PCB. In fact it is possible to totally botch that up and have the thermal monitoring not work at all. EXAMPLE - you have voids or too thick an application of thermal epoxy where the grid of 16 vias are located. But you've squeezed paste out to the sides. Now what happens is the via area becomes a hot spot, the switcher IC overheats BUT the surrounding area of the PCB is cooled sufficiently so that the uController that sense the temperature (inside itself) doesn't heat up as fast as the switcher IC does. So, the switcher IC goes into thermal failure mode but the uController hasn't dimmed the driver.

Anyhow, provide answers to the questions above, also describe your thermal path, i.e. type of thermal epoxy, how thin did you apply it, what is the metal type you used to attach (via the thermal epoxy) to the maxflex gold thermal area, is that an intermediate heatsink and how was it attached to the body of the light?

cheers,
george.
 

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georges80 said:
So, all that's left is updating all the *flex manuals to reflect these new changes and how to select them in the menu system.
George, I see you didn't mention new modes in thermal protection section:
When the internal thermal sensor detects the configured temperature, the light level is dropped to L3 in Multimode, or the chosen "low" level in Duomode (or to L3 if Duomode low was chosen as L4).
 

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georges80 said:
The information to calculate the actual IC failure temperature doesn't exist in a useful format unless you have a LOT of extra information. The Absolute Max Junction temperature is specified as 150C. The datasheet shows the thermal resistance of the package to the thermal pad. But then it goes through the PCB material and that has its own thermal resistance, then you have the thermal paste/epoxy you used with its thermal resistance, then the aluminium or whatever you used and finally to the body of the light itself.

You still haven't told us How many Batteries, What Voltage (total), What Chemistry, How many LEDs, What drive current. With those numbers I can give you an idea of how many watts dissipation will be due to efficiency losses.

The thermal monitoring will NOT be able to catch a bad heatsink attachment to the gold area of the PCB. In fact it is possible to totally botch that up and have the thermal monitoring not work at all. EXAMPLE - you have voids or too thick an application of thermal epoxy where the grid of 16 vias are located. But you've squeezed paste out to the sides. Now what happens is the via area becomes a hot spot, the switcher IC overheats BUT the surrounding area of the PCB is cooled sufficiently so that the uController that sense the temperature (inside itself) doesn't heat up as fast as the switcher IC does. So, the switcher IC goes into thermal failure mode but the uController hasn't dimmed the driver.

Anyhow, provide answers to the questions above, also describe your thermal path, i.e. type of thermal epoxy, how thin did you apply it, what is the metal type you used to attach (via the thermal epoxy) to the maxflex gold thermal area, is that an intermediate heatsink and how was it attached to the body of the light?

cheers,
george.
By your description maybe the thermal epoxy is badly applied. I have used arctic alumina two part epoxy as you recommended on the pdf.
I have used a piece of aluminium almost as big as the driver epoxied to the golden area. Used a thin layer and pressed it well... After it dried applied more AA in a thin layer and glued to the light body made of aluminium too. I cant confirm anything because I cant remove the glued parts now...
Any good solution for the problem? Maybe the LED are also heating the driver.
I'm powering the 7XPG with 6x18650 batteries 3S2P, 11.1V 4800mAh.
What values can we calculate for heat dissipation with the driver at 1000 and 1200mA?

cheers
 

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sergio_pt said:
By your description maybe the thermal epoxy is badly applied. I have used arctic alumina two part epoxy as you recommended on the pdf.
I have used a piece of aluminium almost as big as the driver epoxied to the golden area. Used a thin layer and pressed it well... After it dried applied more AA in a thin layer and glued to the light body made of aluminium too. I cant confirm anything because I cant remove the glued parts now...
Any good solution for the problem? Maybe the LED are also heating the driver.
I'm powering the 7XPG with 6x18650 batteries 3S2P, 11.1V 4800mAh.
What values can we calculate for heat dissipation with the driver at 1000 and 1200mA?

cheers
That's NOT a good combo - 3 li-ion to drive 7 LEDs will hurt the maxflex efficiency. That will cause overheating especially at 1A or 1.2A levels. Running 4 li-ion (series) is pretty well essential to push 1A or 1.2A to those 7 LEDs. 7 x 3.3V typ Vf means around 23V output and at 1A that's 23W to the LEDs. You likely have the driver running maybe 90% efficient depending on the state of charge of the 3 li-ion and any voltage losses in the wiring from the battery pack to the driver.

Also, as Vancbiker wrote - you need a lot of surface area (i.e. fins) to keep the LEDs/housing cool. If the LEDs are getting hot and that heat is closely interfaced to the maxflex heatsink then you have another problem there. Does this problem also occur if the the light has airflow over it or only when stationary?

Basically, the fact that maxflex shuts down after a few minutes it is definitely telling you that you have a thermal issue. Running a 4 li-ion pack will help improve the driver efficiency and that may be just enough to prevent overheating.

cheers,
george.
 
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