micro boostdrive vs flexdrive from 18650 driving 445nm LD

laser_freak · Jul 14, 2010

I've heard that some people are using the flexdrive with an 18650 battery to power their 445nm diode at >1A. The flexdrive can't boost the voltage. The 445nm diodes require >4.2V when driven >1A. An 18650 battery is 4.2V fully charged. How is running these 445nm diodes at >1A on an 18650 battery possible with the flexdrive? It doesn't make any sense. :thinking:

Oh, and on a side note, does anyone know which chip requires heatsinking on the boostdrive?

Solonar · Jul 14, 2010

Flexdrive is buck/boost driver. It can lower or raise the voltage as needed.

laser_freak · Jul 14, 2010

So then what's the point of the boostdrive if the flex drive can also boost the voltage?

Solonar · Jul 14, 2010

Don't know exactly. But the electrical spec's list the flexdrive as ~10% more efficient and better regulated.

Morgan · Jul 14, 2010

The Microboost was developed in response to the higher power Bluray diodes such as the 8x and 12x as these can require voltages above the 5.5V maximum of the Flexdrive. The Microboost is quite capable of driving the 445s up to it's maximum of 1A, (more if you know the correct jumper settings

).

IMO the Flexdrive is perfectly suitable to the 445s and I personally will be using them in future 445 builds. As mentioned above, they are slightly more efficient and you are able to run lower voltage/higher power reds from a 3V or 4.2V source when they only require 2-2.5V, something not possible with the Micrboost. I think the timing of the Microboost release and the coinciding sudden availability of the new diodes explains why there are so many 445/Microboost combos. The are simply available at the same time.

Both are great for the 445s but the Microboost is probably better for high power BR builds.

M

ossumguywill · Jul 14, 2010

The microboost does 1200mA at higher voltages, and the flexdrive sort of maxes out around here as well. They're basically equal for 445nm IMO.

chipdouglas · Jul 14, 2010

i use a v5 and 1 18650, my ma is set to 810, i did run it at 1.0 for a bit. but for no real reason i turned it bac down to 810. and i have about an hour on it so far with my 445.

michael

drlava · Jul 14, 2010

There are a few things that benefit the BoostDrive: It can be TTL modulated, it also can be switched on and off with a low current tactile switch. It has a sturdier potentiometer that allows for more adjustment cycles (the FlexDrive potentiometer is rated for about 15 adjustments max.) Also it's a little more stable when it gets hot.
If you are on the border, I'd suggest going with the MicroBoost for these reasons. Morgan is right about the original reason for the MicroBoost.

ossumguywill · Jul 15, 2010

Yay! For a while I was wondering why I didn't get the flexdrive, but now I'm convinced I made the right choice

I'm still working on PWM, the people at CPF are helping me build an RC timer circuit so that I can measure the time the laser has been off.

Xplorer877 · Jul 15, 2010

Well IMO there is no clear cut choice reguarding which one is better unless you want >1A currents, in which case you may have to be careful about overheating for the diode and driver.

They're both about the same.

Here is the schematic for a slightly higher range on the micro boost.

The one on the left is 560-1100mA, 540mA to 1000mA is on the right.

You'll also slightly more efficiency.

-Tony

ossumguywill · Jul 15, 2010

Tony-that seems strange. The one on the left, take away the yellow line furthest to the right and you get a maximum of 1200mA. Why does adding another resistor decrease output?? :thinking:
Also, why does it make it more efficient?

Xplorer877 · Jul 15, 2010

I had Andrew preset that driver for me to 650mA. I asked him about the solder connection and he told me that it is indeed about 560mA-1100mA. You'll get the highest efficiency by using the highest range that includes your output.

See:

-Tony

Wallydraigle · Jul 16, 2010

Xplorer877 said:
I had Andrew preset that driver for me to 650mA. I asked him about the solder connection and he told me that it is indeed about 560mA-1100mA. You'll get the highest efficiency by using the highest range that includes your output.

See:

-Tony

I wish I'd have seen this last week. I did exactly what you did in the pic only I did it on accident, and destroyed the driver trying to get it back off. If I'd have left it alone it would have been fine.

ossumguywill · Jul 16, 2010

Are you sure? According to lava, using only two of those resistors gives you 1200mA.

Elektrotechniker · Jul 16, 2010

ossumguywill said:
Yay! For a while I was wondering why I didn't get the flexdrive, but now I'm convinced I made the right choice
I'm still working on PWM, the people at CPF are helping me build an RC timer circuit so that I can measure the time the laser has been off.

This does not mean that the ones who are using a flexdrive( such as me ) are unlucky nor did they pick the wrong choice. Personally, I always stick with flexdrives..

kingdave2357 · Jul 16, 2010

Yeah, I always use flexdrives, I had one at 1.3A, have one at 1.1A and another at 700mA. In fact, I never even owned a boost drive, lol.

micro boostdrive vs flexdrive from 18650 driving 445nm LD

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