Some questions about the Shark driver

[Icarus]

Shark Converter board images.




Remora Microprocessor board for the Shark.
http://i221.photobucket.com/albums/d...0_IMG_9829.jpg

Table of Contents:

General Information: LINK (Post #2)

Using external resistors instead of onboard trim pot: Here, Here, Here

Hooking up an external pot: Here (Post #34)

Shark Efficiency graph with 3 Crees: Here ( Post #159 )

Shark Efficiency graph with 6 Crees: Here (Post #159 )

Shark Driving 3 LEDs information: Here (Post #202 )

Remora + Shark + Shark +...: Here

Removing the trim pot: Here

Vout tracks Vin. What's wrong?: Here ( Shark Advisory thread )

[dat2zip]

The Shark has both a voltage feedback and current feedback internally. The regulator can be thought of as a voltage regulator with current limiting.

Sharks sold before Nov 2006
J1 is jumpered and configured for Vout of ~22V

Sharks sold after Oct 2007
J1 has no function. New batch of boards from the CM configuring Vout to be ~26V. All boards sold beginning in 2008 have the copper C soldered onto the backside.

2. What about regulation? The specs says Voltage OR Current???

Yes, it's both. Just like a power supply you can set the voltage and current limit seperately.

If voltage and current regulator is still confusing you. Simply jumper J1 for LED driver applications and the Shark will be a constant current regulator with open circuit protection of ~22V and the trim pot sets the LED current.

3. Is the driver, with and without the jumper, open circuit protected?

Any voltage regulator is "safe" since it will regulate to a given voltage. For the Shark it will regulate to 11.5V or 22V with no load depending on whether J1 is jumpered or not.

4. Last sentence says “The Trim pot input can also be PWM controlled via a microprocessor”.

The trim pot feeds the control pin. If you remove the trim pot you can hook up a microprocesor to control this pin.

The Microprocessor board for the Shark is called the Remora board. The resistor comes with the Remora board (not installed as shown). It makes the two pin header connection to mount the Remora board as the holes on the Remora board are very tiny and most standard wires will not fit. After installation you cut off the upper part leaving two posts.


================================================== ==========
A general rule of thumb to use the Shark.

1) Determine the number of LEDs you want to drive in series. Example: 4 Lux3s.

2) Determine the series voltage of the LEDs at the desired current. Example: 1A which means ~4V/LED and 4LEDs = 4 * 4V = 16V (approximately)

3) Determine the operating and min battery voltages using the total Vf output. Operating is > 1/2 output and min is approximately 1/3 Vout.

Operating should be greater than 1/2 of 16 Volts or a fresh battery pack should be 8+ volts.

At end of battery life your battery voltage should not drop below ~ 1/3 Vout or 1/3 of 16 = 5.3V

In this example a 9V stack of AAs batteries or a 12V stack of AA batteries would be fine for this example. What won't work is 2AAs, 4AAs since the current demand will approach the limit of the regulator.

Example 2:

Three low Vf LuxV. say you have 3 LuxVs with Vf of approximately 7V @ 700mA. That's 21V which is below the 22V open circuit protection (with J1 jumpered).

1/2 21V is 10.5V and 1/3 21 is 7V.

A 12V battery pack would suffice for this application. A 9V battery pack would be marginal for this application.

Wayne

[Icarus]

Wayne.

[Icarus]

What about efficiency of the Shark driver?

Any chance you’ll offer a decent external potmeter to go with the Shark?

Is it allowed/necessary to pot the Shark?

Can't wait for the microprocessor board to be released.
You should give this the highest priority.

Tri-LuxV + microprocessor controlled Shark would be...

[AuroraLite]

What Icarus said! And I can't wait for the others!!

[nemul]

2. What about regulation? The specs says Voltage OR Current???

Yes, it's both. Just like a power supply you can set the voltage and current limit seperately.

Voltage regulation? can it run a hotwire?

[Icarus]

What about efficiency of the Shark driver?

Any chance you’ll offer a decent external potmeter to go with the Shark?

Is it allowed/necessary to pot the Shark?

Can't wait for the microprocessor board to be released.
You should give this the highest priority.

Tri-LuxV + microprocessor controlled Shark would be...

[IsaacHayes]

it can run a hotwire mod if the bulb is rated for 11.5v or 22 volts. That is the limit of the voltage output. Depending on the bulb and what current it draws will also be a limiting factor as the board is only adjustable for 980ma max...

[dat2zip]

The board by default is as described.

There are 0402 SMT resistors that set the voltage which could be changed for voltage regulation to some other voltage like 12.5V, 9V or something else. Even though the resistors are tiny it's not impossible to change with a little care, patience and magnifying devices. A good fine tip soldering iron helps as well.

The primary current sense resistor is a 0.1 ohm resistor which sets the upper end of the current to 1A. Cutting this value to 1/2 would increase the upper current limit to 2A for example. I would solder a 0.05 0603 in place of the current 0.1 ohm sense resistor. Same resistors that are used on Badboy, Nexgen, Wizard and Downboy. Putting a 2nd one on top of the first (two 0.05 ohm resistors) would kick up the output to 4A. Probably not acheivable with a switch limit of 4A, but, the trim pot would allow you to dial out as much as the converter can dish. I would seriously heat sink this if you are driving multiple LEDs with this much current. Three K2 LEDs at 1.5A could be in the 18W range which means the converter losses would be in the 1-2W range for a 80%-90% efficiency. Four K2s would be 24W on the output or more.

The only caveot is to ensure you have a boost configuration under all conditions. Letting Vin rise higher than Vout will put the converter in DD mode and will most likely Fry the converter board, LED and possibly the battery. That's not a good situation.


Since this converter was designed for no holds bar efficiency and power the converter, inductor and diode were all choosen to meet or exceed the requirements of the converter board.

Since the internal switch current limit is ~4A, that would set the input side current limit to 4A. While I simplified it above and may have infered less than that as limits, it was only to make it simple for those who know little about electronics and should for the most part keep the novices from getting into trouble. For the more advanced users this converter board has the most beef no worries about inductor saturating, or diode overheating.

This sucker was built like a tank.

Running large input or output current as usual will always result in losses in the converter board and converter components. Always take this into consideration and a good rule of thumb would be 85% efficiency for computing the power that will be absorbed by the converter board components. if the power losses in the converter are larger than 1W I would consider heat sinking the converter board or at least provide some thermal relief for the heat to migrate away from the converter board.

Wayne

[cy]

thanks for the info, was wondering about the new shark driver

[Icarus]

Did I already mention there are a couple Sharkies on the way to me...

[Sway]

[goldserve]

I have some questions about the PWM to the enable pin?

How does one get the microcontroller powered by the shark board. Is there a fixed voltage out of around 5V? How would you go about designing a pic to be used with this board. Thanks!

[dat2zip]

Adding a microprocessor is left to the user as an exercise.

There is a pad on the converter board that you can pick off the battery voltage, the internal reference, control pin and GND.

With this signals an external board could be devised that housed a linear regulator, microprocessor and support circuitry to drive the control pin.

There are many application notes on Maxim, National, Linear, TI and other web sites on specific ICs and external PWM control

Wayne

[Gryloc]

Sorry to pull up an old post, but could someone tell me if the Shark driver could be used with an external potentiometer? How would one go about doing this (and what value pot must I use)? I love my Fatman, and it is a awesome driver, but I wonder if the Shark would better suite my 4 Luxeon III D-Maglite ran from 6-8AA's. My maglite has a potentiometer built into the head for dimming, so I would hate to get a Shark and find it is difficult to use it with a pot. I worry my Fatman will fail me (and I worry all the time that I may break a wire by twisting the head to dim my flashlight and open the circuit up, destroying the Fatman). I hear how the Shark is built like a tank and it can handle up to 4A of power at a time (from either the input or output). I wonder if George would sell a beefed up Fatman to keep up with the cpmpetition. I heard that you can replace a few resistors and add a diode that can handle greater amounts of current. I hear of people with Fatmans that can take the heat because of this small mod. Anyways, its getting too late here in Ohio. Thanks.

-Tony

[Stuart B]

Hi

Can the shark be used to drive an OSRAM OSTAR 6 chip?

Cheers,

Stu

[dat2zip]

Yes!

Make sure to pot the Shark driver or heat sink as it will be dissipating 1W or so of power in the converter board.

I've already wired one up and put the OSTAR 6 chip on a large processor heat sink with fan. Works great. (J1 needs to be jumpered).

I have another Shark in a Mag host driving three LuxVs. I added a small momentary push button switch so that the default is low approximately 100mA or so. When the button is pressed you get momentary high (burst mode). I like this setup since I only need high on occasion and low is typically more than adequate. I take this one with me when I go geocaching at night. I used my flood PD when I get close to be more stealthy and I used a narrow single Mag Lux3 to look into bushes instead of using my hand/arm.

-Wayne

Hi

Can the shark be used to drive an OSRAM OSTAR 6 chip?

Cheers,

Stu

[Stuart B]

Excellent...just needf to get my paws on a couple these and a couple of 6 chips now .

Stu

Yes!

Make sure to pot the Shark driver or heat sink as it will be dissipating 1W or so of power in the converter board.

I've already wired one up and put the OSTAR 6 chip on a large processor heat sink with fan. Works great. (J1 needs to be jumpered).

I have another Shark in a Mag host driving three LuxVs. I added a small momentary push button switch so that the default is low approximately 100mA or so. When the button is pressed you get momentary high (burst mode). I like this setup since I only need high on occasion and low is typically more than adequate. I take this one with me when I go geocaching at night. I used my flood PD when I get close to be more stealthy and I used a narrow single Mag Lux3 to look into bushes instead of using my hand/arm.

-Wayne

[hank]

I'm staring at my M@g 4D and 5D -- is anyone building Shark-based mods for those yet?

[IsaacHayes]

I think I did my math correctly, and this would work to drive 4xCree's in series that had a Vf of 3.6 at 700ma from 3xNiMH at 3.6volts. Input current would be 3.5amps which is ok. I'd really like to do 1amp to them in parallel via some sort of DB4000 but oh well.

Now a question, will I have to measure current with a DMM when setting the pot to get it at 700ma, or can I just crank it and it will try it's best? Or would that not work and it would drop out of regulation/not function right off the bat?

[Amonra]

i just recieved my shark and have a few questions on how to actually ues it in my application.

I want to run 5 Cree XR-E's in series using a 12V SLA to power them and i want to have a pot to adjust the current between 50 or 100mA and 1A.

I must warn you that i am an electronic idiot so easy step by step instructions are appreciated.

So here are my questions :

when you say jumper J1 u mean solder those two little blobs together ?
how exactly do i add a pot, where should i connect it, and what kind of pot do i need ?
which legs of the pot go where ?
and finally when you say that you pot the board do you mean that you sink it in AA epoxy and stick it to aluminium heatsink ?

Thanks for your help

[dat2zip]

i just recieved my shark and have a few questions on how to actually ues it in my application.

I want to run 5 Cree XR-E's in series using a 12V SLA to power them and i want to have a pot to adjust the current between 50 or 100mA and 1A.

I must warn you that i am an electronic idiot so easy step by step instructions are appreciated.

So here are my questions :

1)when you say jumper J1 u mean solder those two little blobs together ?
2) how exactly do i add a pot
3), where should i connect it
4), and what kind of pot do i need ?
5)which legs of the pot go where ?
6)and finally when you say that you pot the board do you mean that you sink it in AA epoxy and stick it to aluminium heatsink ?

Thanks for your help

I numbered your questions to make them easier to answer.

1) short J1 with a wire. I don't think you can bridge across the gap of J1 with just solder. Use a piece of wire to solder across the two pads for J1.

2) To add a pot requires removing the onboard trim pot and soldering the external pot the pads of the trim pot.

3) see 2)

4) Any potentiometer can be used. Your choice of selection. The only criteria is the value of the Potentiometer must be 20K. (I would get an log or volume pot personally vs a linear taper pot)

5) There are three connections on the pot. Solder them to the three connections of the trim pot you removed off the board. There should be the two ends and the wiper.

6) The board *Needs thermal heatsinking* . You need to do something to pull the heat off the board. I would suggest thermally glueing it to the heatsink along with the LEDs, but, that's application dependant. Personally I've blobbed down some AA adhesive and pressed the converter board into it to glue it to the heatsink. Just be careful to not short any of the connections on the backside to the heatsink. You probably don't need to heatsink if your output Power is less than 8W of power. After that I would highly recommend thermally heatsinking the converter board. Assume 80% efficiency. 10W of output (LED) power means 2W on the converter board 80% efficiency, 20% inefficiency = 2W. 80% is just a rule of thumb, but, when driving many LEDs you are effectively driving a lot of Watts and need to take power more seriously than a single LED solution.

-Wayne

[Amonra]

Thanks for your reply. just one more question
for the external pot which ends and wiper go where. there are three connections on the trimpot but they are not labelled so where does the first end go ? the second end ? and the wiper ?

Thanks again

[IsaacHayes]

Wayne, can you verify I can drive 4 cree's at 700ma with 3.6v input (worse case)?

[dat2zip]

Wayne, can you verify I can drive 4 cree's at 700ma with 3.6v input (worse case)?

Your input/output ratio is 3.6V:~14V or ~1:3.9

Simplified calculation is for the current knowing the Vin/Vout ratio and apply the same for the current. 14V@1A equal 3.9 X 1A to get the input Current = 3.9A. That's too much for the Shark. 14V @ 0.7 = 0.7 * 3.9 = 2.73A. That's possibly OK since we did not factor in the efficiency of the converter so input current will be higher than 2.73A by another 15% or so which will go over 3A again, but, not by much. So, 700mA is around the limit for the Shark in this configuration.

It really doesn't matter if you crank it all the way up to 1A. If the converter can't deliver 1A it will deliver the max it can deliver. If that's OK with you, run it to the hilt. If you want constant light for longer duration turn it down a bit.

-Wayne

[dat2zip]

I hope 3.6V is the near dead battery state. That's where you need to compute this equation as higher battery voltages will not put as much demand on the Shark.


This is true for any boost configuraration.

For any boost configuration determine your battery chemistry and find what you consider the end of life of the battery. For NiMH and Alkaline that's around 1V/Cell. ~2V for primary Lithium and ~3V for rechargeable li-ion.

Then compute your LED string (assuming they are wired in series).

Compute your input/output voltage ratio.

Use the input/output voltage ratio to determine the input battery current for various output current schenarios and factor in anywhere from 10-30% losses in the converter.

==========================================
Example: 3 Alkaline, 3 Lux3s

Battery near dead state: 3 cells * 1V/Cell = 3V minimum.

Three Lux3s (J bin) 700mA: ~ 3.7V/LED = 3.7V * 3 = 11.1V

Input output ratio 11.1/3V 3.7:1 or 1:3.7 depending on direction.

Efficiency 85% (For this example)

========================================
Substitute into the Power in = Power Out equation.

Power in = Power out =
Vin * Iin = ( Vout * Iout ) / effficiency

Substituting we have 3V * Iin = (11.1V * 0.7A) / 0.85

Solving for Iin we have Iin = 9.14W / 3V = 3.04A.

Once you solve for Iin the only question remaining is whether the converter can suck that much input current (usually the limiting factor).

The IC used in the Shark is rated for 3A and I have recommended to use 2A as a safe number for maximum input current.

-Wayne

[IsaacHayes]

Yes good info thanks. Yeah 3xNiMH is the source. They usualy stay higher than 1.2 each, around 1.35 even settled. Thanks for clearing up the current in limits, I was thinking 4amps in was max..

[CodeOfLight]

I was thinking of using the shark to mod a replacement for my 18v Ryobi flashlight. I am going to use 5 cree XR-e in series at 700 ma. It sounds like it would work based on some of the earlier replies. I would want to heatsink the board. (Or put a little micro fan inside the casing )

[dat2zip]

4 Amps is typical, but, 3A is minimum, 5A max. It's is probably more like 4A, but, it could be as low as 3A and 3A is what you should use worst case. If it's slightly past 3A you are probably still OK. As you move away from Mminimum it's more probably you might get an IC that is closer to min and you mod may not run full power. Then again, for a single mod it's probably not an issue.

If you were to do a production of lights you should only use the mimimum as this would ensure all the lights will meet specifications and you would not have drop out in production due to yield issues.

(I still have my Agilent Hat on and design around worst case numbers, thus, I would always use 3A to ensure 100% yield in production).

-Wayne

[IsaacHayes]

ahhh. Got ya!