[[ GXB17 Driver ]] – 17mm 6V 3A / 12V 1.5A Constant Current Programmable Single-Cell Boost Driver

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[[ GXB17 Driver ]] – 17mm 6V 3A / 12V 1.5A Constant Current Programmable Single-Cell Boost Driver

Hello all,

I finally managed to grab some time and spent last weekend reworking my GXB20 driver to a 17mm form factor, which was by far the most popular request. Introducing the 17mm GXB17 6V 3A boost driver! smile For those unfamiliar with my GXB20 driver, please take a look here: http://budgetlightforum.com/node/52517 

 

Drivers for Sale?

I've been getting a few messages if these drivers are for sale, so I thought I'd just answer them here! Thanks for you interest, but unless stated otherwise. I have none for sale yet. In fact the PCBs have just been sent for fabrication (as of 10th June) and I still need to assemble and test them. The PCBs will take at least 1-2 weeks before I even get my hands on them. In addition, even after development I will not be able to offer any assembled drivers for sale, unless I get some help in getting them semi-mass produced at the factory. Finally, note that I really wasn't intending this to be a commercial driver - it was always meant to be a hobby, just for fun project for my own flashlight! However if you are interested please feel free to follow this thread and I will provide updates whenever possible! 

 

TL;DR: 

The GXB17 is a smaller form factor of the GXB20 driver I made for fun not to long ago. The GXB17 (as is the GXB20) is a simple constant-current single-cell (e.g. one 18650) programmable boost LED driver, designed specifically to be powered by a single lithium cell. It is designed to drive 6V 3A LEDs like the XHP50 and Nichia 144 LEDs, but can also be configured to run in 9V and 12V output, with a nominal maximum power of around 18+W and higher in boost for shorter durations.

The GXB17 incorporates all the features of the GXB20, but as its name implies, is a 17mm diameter driver.

The GXB17 is a true constant current driver which takes drive current feedback and regulates the output voltage to match the desired current. The driver is fully programmable with an on-board ATtiny84A and includes features such as temp-sensing, battery voltage sensing, off-time memory, and runs at >90% efficiency at most output levels. It also has pins for an optional e-switch if desired.

Finally, the GXB17 was designed as a fun hobby project, and definitely not designed to be a commercial driver in mind - i.e. no optimization was made for cost, component count or ease of fabrication! That said, it's a fairly full featured driver and I hope it will be something all hobbyists here can enjoy!

Current Status:
GXB17 v1 PCBs have arrived and I have got one soldered up. Testing in progress..



Feature List:

  • Input - 1S (e.g. single 18650), ~2.6V to ~4.3+V
  • Output - 6V 3A or 12V 1.5A nominal
  • True Constant Current control, 256 levels 
  • 17mm Diameter
  • Attiny84A Programmable
  • Off-time capacitor with EEPROM memory
  • Temperature Sensing
  • Battery Voltage Sensing
  • Extra GPIO for Mode or E-Switch with your desired firmware
  • Efficiency >90%+ for most output levels
  • 2 Layer PCB 

Design and Operation

Designing the GXB17 was a little bit more work, mostly because of its much smaller size than the GXB20. It only has 72% of the PCB space as the GXB20, or 60% the footprint of competing 22mm drivers! In addition, I wanted to design it to fit OSHpark PCB fab requirements, and not go to a 4 layer board. Furthermore, I wanted to incorporate all the features of the GXB20 with no compromises in power output or features. I know the design can be significantly optimized for less parts etc, but I liked the configurability aspect of the GXB20, so I simply ported over the entire schematic and did a new layout for the GXB17 with only a few component optimizations.

The result is the exact same functionality of the working GXB20 but in a smaller form factor, with the following features:

  • (1) proper constant current operation and brightness modes
  • (2) programmability
  • (3) safety features (over-temperature cut-off etc)

(copied from my GXB20 post:) For adjusting brightness, a simple and commonly done way is to have a fixed boost voltage, run the LED across a current limiting resistor, and then use a FET and PWM to control LED brightness. This works OK, but due to the V_fwd inconsistencies of LEDs, this can lead to widely differing LED brightness. In addition, PWM generates flashing/strobe effects, which is not as pleasant as a true constant-current limiting circuit. In the GXB17/20, the LED I_fwd current is constantly sampled across a small current-sense resistor. This value is then amplified via a digitally variable amplifier (controlled via an Attiny84A) and fed into the boost power circuit. The boost circuit then regulates the voltage to maintain the desired current.

For programmability, I decided to go for an Atmel ATtiny84A instead of an Attiny85 due to the fact that it came in a very small 3x3mm QFN package, has EEPROM for storage of memory modes, allows me to use the hobbyist-friendly Arduino environment for sharing / open-source, and comes with a lot more GPIO for additional features. The next revision will probably use a newer ATtiny841.

Other features includes things like battery sensing (so I can turn off the LED drive if the battery voltage falls too low), as well as real-time temperature sensing for dynamic LED brightness control if it gets too hot. Extra GPIO(s) is also available for e-switch and/or mode operation with modifications to the firmware!

 

  

Here's a render of how the board layout looks like. Care was taken to optimize power and logic traces so they interfere as little as possible, yet still fit completely on a 17mm 2-layer PCB - and I tried to use no smaller than 0402 components for almost the entire design. Certainly going 0201 and using 4 layers would be even more optimal, as would be using stricter PCB rules such as 4/4mil or 3/3mil! But then I wouldn't be able to order them on OSHpark or cheaper fab houses.

p.s. It looks like the outside ground ring is not 'closed' but it is in fact closed. Just that there is a little gap due to the soldermask - I had to add the soldermask since I could not avoid a small trace running right along the periphery of the board. 

Since the design is basically the same as the GXB20, the same firmware can also be used on the GXB17.

 

   

Above shows a quick preliminary to-scale comparison between the GXB20v2 and the GXB17v1 driver.

 

   

Above is the layout of the driver; a little hard to see but the board space is fairly well used up, though I think I could probably optimize it even more with a little more work! Programming is done via a 50mil 6-pin pad array where a 6-pin header can be used via contact-programming. I decided not to go for the molex micro-stack header since I had a poor experience using it in the GXB20 where it would often get stuck and come out.

Right now I've ordered a few preliminary PCBs to assemble and verify the design.

Note that again this driver was designed as a 'for fun' driver, mostly because I wanted a small flashlight driving a big LED. I never expected such a good response from it, nor did I design this for commercial manufacturing (where I would have optimized component choice, cost, component count etc), but I'm looking forward to seeing where this will go.

Hopefully this will be a driver which people will find useful. sealed

Thanks for reading and I'll continue to post updates as this project progresses. 

Website: www.loneoceans.com/labs/

GXB20: Single-cell Programmable XHP50/144M 20mm Boost Driver (version 2)

GXB17: Single-cell Programmable XHP50/144M 17mm Boost Driver (version 1)

Edited by: loneoceans on 07/05/2017 - 18:14
DavidEF
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Nice! Thumbs Up

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Awesome now need to make like 1000+ units

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GREAT!


find all available items in this list

i launched my new blog - all deals for members without MAP B$ Wink

find a short description about my idea here

 

if you want to buy a flashlight or battery for a better price: just send a mail - i will try to save you money!

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Impressive!! Wink

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This is what I call breakthrough tech! Great work.

Are there any functional shortcomings to the 17mm driver which the 20mm driver doesn’t have? It looks like you have to use smaller spring to save space – don’t know how that affects function.

Questions/Answers here: http://www.answersingenesis.org/home/area/qa.asp “So then, each of us will give an account of himself to God.” Romans 14:12

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This is what we have been needing for a long time. If it can handle 20W long term that is perfect for most edc style lights and a turbo burst of say 30W would be perfect.

I assume that it could be tweaked to boost up to 12V for an XHP35 correct?

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My LED Test series - XP-L2 V5  - Nichia 219C 90+ CRILatticebright "XM-L"XHP35 & PWM efficiency - XHP50 - XP-L V5 - XM-L2 U2 - XP-G3 S5  - XP-L HI V2 - Oslon Square & direct comparison to Djozz tests - Nichia 319A - Nichia 219B 9080 CRI - Nichia 219C D320 - Nichia 229AT

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Very nice !

=====================
_“For programmability, I decided to go for an Atmel ATtiny84A instead of an Attiny85 due to the fact that it came in a very small 3×3mm QFN package, has EEPROM for storage of memory modes, allows me to use the hobbyist-friendly Arduino environment for sharing / open-source, and comes with a lot more GPIO for additional features.” _

open source firmware ?

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cncyana wrote:
This is what I call breakthrough tech! Great work. Are there any functional shortcomings to the 17mm driver which the 20mm driver doesn't have? It looks like you have to use smaller spring to save space - don't know how that affects function.

I hope not! It shares basically the same schematic except for a few components which are smaller / more power dense, but otherwise will have all the same features. I don't see how using a slightly smaller spring would affect the function, but to test this out, I've also ordered a Convoy S2+ host to build this driver into a real flashlight to see how it does in real life. 


Texas_Ace wrote:
This is what we have been needing for a long time. If it can handle 20W long term that is perfect for most edc style lights and a turbo burst of say 30W would be perfect. I assume that it could be tweaked to boost up to 12V for an XHP35 correct?

That's correct. I plan to make 2 versions on the bench to test - a 6V 3A nominal one hooked up to a 144M/XHP50, and a 12V 1.5A nominal one hooked up to a XHP35, and see how much I can push them. The difference between 12V and 6V versions would be modifying a few of the component values for better efficiency at the desired output voltages. 

 

Evgeniy wrote:
Very nice ! ========================= _"For programmability, I decided to go for an Atmel ATtiny84A instead of an Attiny85 due to the fact that it came in a very small 3x3mm QFN package, has EEPROM for storage of memory modes, allows me to use the hobbyist-friendly Arduino environment for sharing / open-source, and comes with a lot more GPIO for additional features." _ open source firmware ?

Yes I will be uploading all the schematics and firmware to my webpage soon so anyone can modify it to suit their needs or contribute to make it better! I'm not the best designer or firmware writer and I'm sure there are lots of folks here who are far better than myself! Smile

Website: www.loneoceans.com/labs/

GXB20: Single-cell Programmable XHP50/144M 20mm Boost Driver (version 2)

GXB17: Single-cell Programmable XHP50/144M 17mm Boost Driver (version 1)

Tjhosan
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Texas_Ace wrote:
This is what we have been needing for a long time. I assume that it could be tweaked to boost up to 12V for an XHP35 correct?

Oh yeah! 12v and 2.5-3A 17mm or 20mm driver would be crazy Love

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Tjhosan wrote:
Texas_Ace wrote:
This is what we have been needing for a long time. I assume that it could be tweaked to boost up to 12V for an XHP35 correct?

Oh yeah! 12v and 2.5-3A 17mm or 20mm driver would be crazy Love


I doubt that very much!

2S 8.4 volt in to 12v-2.5a would be feasible.

KB1428 “Live Life WOT”

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Tjhosan wrote:
Texas_Ace wrote:
This is what we have been needing for a long time. I assume that it could be tweaked to boost up to 12V for an XHP35 correct?

Oh yeah! 12v and 2.5-3A 17mm or 20mm driver would be crazy Love

I kind of doubt it will be able to handle 3A at 12V but 2A might be possible depending on the exact efficiency involved. Although 2A is about perfect for an xhp35 for longer term use, over that and you get quickly diminishing returns. Although a turbo mode of 2.5A for ~45 seconds or so could be possible.

If guns cause crime, then pencils cause misspelled words.

In general, the art of government consists of taking as much money as possible from one party of the citizens to give to the other. -- Voltaire (1764)

Texas Avenger Driver Series

My LED Test series - XP-L2 V5  - Nichia 219C 90+ CRILatticebright "XM-L"XHP35 & PWM efficiency - XHP50 - XP-L V5 - XM-L2 U2 - XP-G3 S5  - XP-L HI V2 - Oslon Square & direct comparison to Djozz tests - Nichia 319A - Nichia 219B 9080 CRI - Nichia 219C D320 - Nichia 229AT

Complete collection of all my LED tests

Tjhosan
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I am using a H2-C running at 2A with 1s input now so i know it should be doable.

I will be happy with 2A aswell if i can program the driver Big Smile
And a little turbo mode cant hurt aswell hehe

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Texas_Ace wrote:
Tjhosan wrote:
Texas_Ace wrote:
This is what we have been needing for a long time. I assume that it could be tweaked to boost up to 12V for an XHP35 correct?

Oh yeah! 12v and 2.5-3A 17mm or 20mm driver would be crazy Love

I kind of doubt it will be able to handle 3A at 12V but 2A might be possible depending on the exact efficiency involved. Although 2A is about perfect for an xhp35 for longer term use, over that and you get quickly diminishing returns. Although a turbo mode of 2.5A for ~45 seconds or so could be possible.


Triple XHP35 doesn’t have problems with diminshing returns after 2A. Wink
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This is awesome. Please tell me you are going to offer these for sale? I want a Convoy C8 with an XHP35 so badly.

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Nice. You are very clever loneoceans. Thumbs Up

My current and or voltage measurements are only relevent to anything that I measure.

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Texas_Ace wrote:
If it can handle 20W long term that is perfect for most edc style lights and a turbo burst of say 30W would be perfect.

Nice joke ) or are you diver?
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If one of these could be made in 36mm and be programmed to do 1s —> 12v@1-1.5A for E-switches then this would be awesome as a TN4A driver with the carrier modified to run 1s4p.

Just an idiot with a soldering iron.

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loneoceans wrote:

 


cncyana wrote:
This is what I call breakthrough tech! Great work. Are there any functional shortcomings to the 17mm driver which the 20mm driver doesn’t have? It looks like you have to use smaller spring to save space – don’t know how that affects function.

I hope not! It shares basically the same schematic except for a few components which are smaller / more power dense, but otherwise will have all the same features. I don’t see how using a slightly smaller spring would affect the function, but to test this out, I’ve also ordered a Convoy S2+ host to build this driver into a real flashlight to see how it does in real life. 



Texas_Ace wrote:
This is what we have been needing for a long time. If it can handle 20W long term that is perfect for most edc style lights and a turbo burst of say 30W would be perfect. I assume that it could be tweaked to boost up to 12V for an XHP35 correct?

That’s correct. I plan to make 2 versions on the bench to test – a 6V 3A nominal one hooked up to a 144M/XHP50, and a 12V 1.5A nominal one hooked up to a XHP35, and see how much I can push them. The difference between 12V and 6V versions would be modifying a few of the component values for better efficiency at the desired output voltages. 


 


Evgeniy wrote:
Very nice ! ===================== _“For programmability, I decided to go for an Atmel ATtiny84A instead of an Attiny85 due to the fact that it came in a very small 3×3mm QFN package, has EEPROM for storage of memory modes, allows me to use the hobbyist-friendly Arduino environment for sharing / open-source, and comes with a lot more GPIO for additional features.” _ open source firmware ?

Yes I will be uploading all the schematics and firmware to my webpage soon so anyone can modify it to suit their needs or contribute to make it better! I’m not the best designer or firmware writer and I’m sure there are lots of folks here who are far better than myself! Smile


Have you thought about making a 9V version too?
It would be useful for 3s 3V setups, bringing better efficiency than linear drivers.
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Would love to play with one of these when they are working. What boost IC are you using? From the pictures in the GXB20 post it looks like possibly TPS61088?

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TPS61088? The official datasheet lists 12.6V as maximum output voltage, with 13.2V output overvoltage protection. That is pretty limited for XHP35 handling, though it may suffice for just 1.5A of output.

 

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I could be wrong about the IC, but the pictures of the assembled GXB20 look to have a similar footprint. I skimmed through the GXB20 thread and didn’t see the IC model mentioned, maybe I missed it. Will wait for loneoceans to chime in. Either way this is a very exciting driver.

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Jensen567 wrote:
Would love to play with one of these when they are working. What boost IC are you using? From the pictures in the GXB20 post it looks like possibly TPS61088?

 

Barkuti wrote:

TPS61088? The official datasheet lists 12.6V as maximum output voltage, with 13.2V output overvoltage protection. That is pretty limited for XHP35 handling, though it may suffice for just 1.5A of output

 

Yes the GXB20 and GXB17 both use the TPS61088 boost converter. Barkuti is correct with the maximum output voltage possible is not much higher than just over 12V, which does limit output of the XHP35 to just about 1.5A in most applications. However keep in mind that the (1) I designed the GXB20 specifically for 6V 3A operation and (2) driving the XHP35 to ~1.2A will already produce 300% rated luminant flux (though with proper heatsinking etc more is just fine) and (3) the GXB17 was done over a weekend just to port the GXB20 to a smaller package! 

So yes it's definitely not a 'ultimate' driver right now, but hopefully with a bit more time, I can get closer to it. Smile 

Agro][quote=loneoceans wrote:

Have you thought about making a 9V version too? It would be useful for 3s 3V setups, bringing better efficiency than linear drivers.

As for 9V output on one cell, sure it's not a problem. Just need to look into refining the component choice (if at all) and it should work just fine and at full 18W+ power output.

Finally, I note that TI just very recently released the TPS61178x which was only available for purchase just after I had designed the GXB20. This is an even more attractive IC with essentially the same power handling capability and with 20V output max in a slightly smaller package, but compromises with higher resistance internal FETs, is difficult to hand-solder, and... is $5 instead of $3 which is a significant BOM increase. I will be tracking PMICs closely and see if the future mk ii versions of the GXB20 and 17 can benefit from them.

Once I get the GXB17 up and running I hope to get some feedback from members here and see how I can make better Big Smile

Website: www.loneoceans.com/labs/

GXB20: Single-cell Programmable XHP50/144M 20mm Boost Driver (version 2)

GXB17: Single-cell Programmable XHP50/144M 17mm Boost Driver (version 1)

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The TPS61088 is not so bad, yes not the ideal XHP35 IC, but for 6V or 9V setups it is perfectly adequate. I have been playing around with the H1-A alot recently and really like it. It is also based on the TPS61088. Taking that driver, adding a customizable UI, and shrinking it to 17mm is a big win in my book.

I also suspect you will be able to push closer to 24W output without much issue, the driver will get hot though, so probably best to have a timer on that mode.

If you have LVP on the microcontroller I would suggest going all the way down to the 2.7V allowed by the boost IC, the 3.0V cutoff on the H1-A is one of my complaints.

Would be happy to test the driver out on the bench and give some feedback once it is up and running, feel free to PM me if you’d be interested in that. Im impressed with what you have so far!

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loneoceans][quote=Agro wrote:
loneoceans wrote:

Have you thought about making a 9V version too? It would be useful for 3s 3V setups, bringing better efficiency than linear drivers.


As for 9V output on one cell, sure it’s not a problem. Just need to look into refining the component choice (if at all) and it should work just fine and at full 18W+ power output.


BTW, just made some calculations..
Aspire 18350 discharged to 2.8V, 3*XP-L2 W2, 80% efficient optic. Target OTF lm: 100. Ambient temp: 25 C.
Linear driver with 350 mA PWMed to 201 will run for 347 minutes.
GXB20 v1 9V 66 mA using your efficiency numbers over a smaller voltage range (98% efficient): 474 minutes
GXB20 v1 9V 66 mA assuming that it’s much worse at lower voltage (overall 90% efficient): 436 minutes

That’s a major difference….

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Correction GXB20 is 93% efficient at this level. Also, I miscalculated temperature.

Linear driver with 350 mA PWMed to 203 will run for 345 minutes.
GXB20 v1 9V 67 mA using your efficiency numbers over a smaller voltage range (93% efficient): 448 minutes
GXB20 v1 9V 67 mA using your efficiency numbers over a smaller voltage range (85% efficient): 410 minutes

Still hopefully conservative 20% runtime increase.

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nice numbers!

thanks Beer

find all available items in this list

i launched my new blog - all deals for members without MAP B$ Wink

find a short description about my idea here

 

if you want to buy a flashlight or battery for a better price: just send a mail - i will try to save you money!

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Speed4goal wrote:
Awesome now need to make like 1000+ units
This!

I’d like to buy several fully assembled myself!

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One thing which just a while ago came to my mind with this ∅17mm and ∅20mm dual design is that, in flashlights with generous 20mm driver shelf height, it should be possible to install (at least) an additional ∅17mm driver board above the ∅20mm base one, running both in parallel. I do not really know how much would be the total driver team height, yet I suspect that even if power handling would need to be restricted for the floating board(s), this could be rather interesting for XHP70s and/or power freaks.

Of course, with this massive power handling from a 1S source a good low RDS(ON) MOSFET tail switch would be advisable/required.

 

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Oh! Another related thing. I must admit I find a smidge bit irking the usual practice of specifying a “nominal” single output voltage for constant current drivers. In my honest opinion, I'd specify the effective output voltage range. For example: GXB17 3A 4.8-7.4V.

Now, for the folks who may complain, it is best for it to be this way so we can educate the philistines.

 

P.S.: wanting to check out what happens to products with poor labeling? Take a peek at those 3×3 10W “12V” led arrays at Banggood, plenty of customer reviews with fried leds after hooking them to random 12V constant voltage supplies. Just remembered this (LoL!). 

Rufusbduck
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Joined: 04/04/2012 - 15:34
Posts: 10365
Location: Golden state

Pretty phenomenal work loneoceans. Driver development has been a strong suit here in recent years thanks to members giving their time and skills to the process. It wouldn’t happen otherwise. Thank you for these

Three Tanna leaves to give him life, nine to give him movement. But what if he eats the whole bag?

Scott

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