17mm driver design.

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Tedfs
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17mm driver design.

I almost got into designing my own LED driver a year ago but settled on easier options. Just work so many hours it's hard to split my free time.

What I want to learn how to design is a 17mm driver with 8* AMC7135 ( 380mAh version ) for 3.04 A total. Constant current with reverse polarity protection and one mode and no PWM. I honestly have no idea where to start.

I've used DX 1400 mAh drivers and soldered on extra AMC7135 chips. Ordered custom flashed, single mode drivers. But what I'd really like is to have exactly what I need ready to go. Learning how to make this will help me understand the programs, layout and other aspects of ordering so I can try other designs.

Any recommendations on where to start for such a design ?

Rufusbduck
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See This thread on designing pcb’s using eagle software.

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

Scott

Tedfs
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I have and am watching those videos but didn't want to clutter up that thread with one specific design.

WarHawk-AVG
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You can take one of the already built 17mm ATtiny13 drivers, just not put the ATtiny13 on there…then jumper pin 6 to the bat +

As soon as the clicky sends power thru it…the light comes on (more or less an always on signal to the enable pin on the regulator chips), 1 mode…wide open but regulated thru the 7135’s

http://budgetlightforum.com/node/29562

If you want to “learn” how to do it…Mattaus has done a VERY good howto video series on building drivers

Or do you want to just have the full 105C, programmed with a full 100% on firmware so you still retain low voltage signalling and reverse polarity protection?

It would be cheaper to not have to put the MCU on the board if you want a single mode always on driver…

Tedfs
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That's pretty much what I'm doing now with DX 1400mAh boards and soldering on extra AMC7135 chips.

What provides reverse polarity protection ?

WarHawk-AVG
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Tedfs wrote:

That’s pretty much what I’m ding now with DX 1400mAh boards and soldering on extra AMC7135 chips.

What provides reverse polarity protection ?


diode…put the battery in backwards, diode won’t let current flow, correct direction, it will flow and light will come on
Tedfs
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That's what I thought. So an 8* 7135 board with a diode should be pretty straight forward to design. Just have to learn the software.

 

Thank you.

WarHawk-AVG
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Here is a slightly larger than 17mm (17.42×17.42 mm) 10*7135 build (by C_K), uses a 6 pin PIC chip…but would work just fine for your idea

https://oshpark.com/shared_projects/pfSZK2ak

Solder in a jumper between pin 1 and pin 5 of where the U1 should be…the little diode (D1) on the board feeds pin 5, but since you jumpered to pin 1, all the 7135’s would come on as soon as the button was clicked…but if the battery was in backwards, the diode would prevent any current from flowing and the 7135’s wouldn’t come on

Tedfs
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What is the function of the 6 pin PIC chip ?

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unknown…C_K is one of the guru’s of the PIC

Oh duh…misread your previous post

It is the MCU that controls the PWM, it’s a different type MCU from the Atmel ATtiny13 (8 pin IC) or the ATtiny10 (6 pin IC)
It is what control the ability of the 7135’s to make the PWM to make lower modes

Tedfs
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Must be it holds the UI firmware.

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correct

Rufusbduck
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If you don’t need low voltage monitoring then you could do this with just the diode and 8 – 7135 chips. No mcu.

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

Scott

Tedfs
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Thank you to everyone so far. This really helps.

So much to learn yet. Guess my next question would be how do I determine what size diode is needed ?

This driver will be for an XMl-2 P60 type drop in running on two CR123 batteries but could also end up being run by one 4500mAh - 4700mAh 26650. I understand the function of the AMC7135 but not how to determine the correct size diode for this 17mm application.

RMM
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As others have pointed out, there is really no point in designing and building a driver if you just want a 100% only mode with 8x7135.  Just jumper two pins and be done with it.  It will be cheaper than you could buy the parts individually for.  

Running CR123 primaries at 3A is dangerous.  I have tried it and I absolutely would not recommend doing it. 

Mountain Electronics : batteries, Noctigon, and much more! What's new? 

Rufusbduck
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If you understand the concept of stacking there are 4 × 71:5 boards that already have the diode. Or take a 105C driver and flip it’s diode around to jumper from led+ to the right hand pin of the nearest 7135. This will fix the driver to high.

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

Scott

Tedfs
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I don't understand the circuit enough to know which two pins you are speaking of to jump together.

Caution on running primaries at 3A is understandable. A few boards for testing is all I'm looking for as the primaries I use are 1400mAh. I'm shifting towards 26650 and 18650 rechargeables currently but still like to experiment and see what can work.

I like all my body parts where they are and appropriate PPE is applied when applicable.

Rufusbduck
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Here’s a link to a picture of a driver with the parts labeled. The end of the diode with the line goes to the closest pin above it on the chip next to the “+”. The other end of the diode stays on the same pad it’s on now. Feeding power to the 7135 this way will keep it turned on. Since all the 7135 chips are in parallel the rest of them will be turned on as well. The diode will no longer feed power to the mcu or voltage ladder so no current will be wasted there, they will be inactive components.

In normal operation the mcu sends a signal to those identical pins on all of the 7135 chips on the board and turns them off and on rapidly (pwm or pulse width modulation) in order to generate the various brightness levels and blinky modes. This mod just bypasses the mcu and locks all of the 7135 chips in the on position.

Pretty simple, just desolder the diode and turn it around moving it a few millimeters.

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

Scott

Tedfs
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That makes sense, thank you for the link. I still want to design my own though. I enjoy learning new things and that's the whole point of DIY to me really.

Rufusbduck
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Good, I like to see that.

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

Scott

Tedfs
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What would be the proper diode to use with 8* AMC7135 chips ?

The DX 1400 mAh boards I’ve been soldering extra chips onto have two types.

 

Rufusbduck
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Those two boards are identical in function and either diode type will do the job. The diode allows current to flow from the center via(plated hole) to the trace with “Q2” and “D2” in white print over it. That trace leads to the same pin on each of the 4 chips and turns the chips on. This allows current to flow from the pad opposite the diode through the led back to led-, then through each of the 4 chips (350mA each) to the ground tabs (larger single pin) and the ground ring that connects through the host to the switch and battery -.

If you were to put the battery in backwards the diode would prevent current flow in the wrong direction and possible harm to the chips.

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

Scott

Tedfs
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So in theory, the same size diode should be fine for an 8* AMC 7135 board since I've been soldering on extra chips to these boards for almost 2 years anyway and they have been working fine. No idea what size diode that is though, no markings at all to identify it.

So much to learn still. This is incredibly fascinating to me yet fun at the same time. Thank you for all the help and knowledge so far.

Rufusbduck
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The current needed to activate the gate is very small, maybe .2 mA per chip and this is the only current that passes through the diode. Using a diode with a lower voltage drop or bypassing it means the driver will begin to dim slightly later but without an mcu with low voltage monitoring you will need to watch this carefully and recharge the cell as soon as it begins to dim to avoid over discharging the cell.

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

Scott