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Thread: Shark Buck

  1. #1

    Default Shark Buck

    Most of you know or are familiar with the Shark and Blue Shark.

    We are adding to the family the Shark Buck a step down converter based on the same IC used in the Shark and Blue Shark.

    General overview.

    The Shark Buck is the same diameter (0.75") as the other two, has the same trim pot and trim pot functionality. I Remora can be mounted on the Shark Buck and behave the same as the regular Shark (Note 1).

    Since the control trim pot functions the same as a regular Shark you can use one external pot to control both the Shark and Shark Buck. Thus, one external pot or one Remora could control two Blue Sharks and one Shark Buck to drive two strings of 4 single LEDs in series and the Shark Buck could drive one Seoul P7 or one Cree MC-E LED. Many other combinations can be had with this versatile common control interface.

    Since the Shark Buck steps down the output current max is greater than in a boost configuration. I have tested the Shark Buck with 3A to the load and it behaves nicely.

    Here are some numbers I graphed from a Revision 1 board.

    Code:
          Vin   Iin   Vout   Iout   (Watts)   (Watts)   %       
    15   0.95   3.635   3.037   14.1455   11.0395   78.0%       
    14   1.03   3.523   3.053   14.3067   10.75572   75.2%       
    13   1.11   3.516   3.063   14.3079   10.76951   75.3%       
    12   1.2   3.509   3.073   14.268   10.78316   75.6%       
    11   1.31   3.504   3.087   14.2659   10.81685   75.8%       
    10   1.45   3.499   3.105   14.3405   10.8644   75.8%       
    9   1.62   3.497   3.122   14.4018   10.91763   75.8%       
    8   1.83   3.495   3.14   14.4387   10.9743   76.0%       
    7   2.082   3.489   3.153   14.34498   11.00082   76.7%       
    6   2.439   3.48   3.154   14.36571   10.97592   76.4%       
    5   2.74   3.453   2.999   13.3986   10.35555   77.3%


    I may have an error at the 15V input as the efficiency rose when it should have continued the downward slope. The line should be straighter, but, I believe this is due to the time it takes for me to read and write the measurements down the board and LED temperature moved and made for a slight error in measurement. If you straighten out the line you can see that around 5V the efficiency is just over 79% and at 14 Volts it has dropped to around 77% efficiency. I would draw a straight line from these two to get a more realistic graph of efficiency.

    Note in the numbers that the current to the LED was slightly higher than 3A. Unlike other converter boards this one is delivering 3A.

    The Shark Buck also has reverse battery protection and accomdates the same copper C as on the regular Shark for optimum thermal transfer to the heat sink.

    There are two sense resistors on this board making it easier to generate a valid output current combination.

    One 0.1 ohm resistor = 1A max.
    Two 0.1 ohm resistors = 2A max.
    One 0.1 ohm, one 0.05 ohm = 3A max. (maximum output configuration)


    I'm sure you have questions and feel free to post them here in this thread. When I get more pictures and data I will add them to this thread.




    Notes:

    1) The inductor placement encroaches into the area under the Remora and raises the height of the Remora. Once mounted the completed assembly will be thicker than a regular Shark + Remora.

    17MAR2014:

    Shark Bucks can not be paralleled for more output current.
    Last edited by dat2zip; 03-17-2014 at 12:05 PM. Reason: parallel converter boards note

  2. #2
    Flashaholic* LED Zeppelin's Avatar
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    Default Re: Shark Buck

    Great news Wayne! This will really open doors.

    What is the voltage limit?
    How many P7s can be driven in series?
    When will it be available?
    Last edited by LED Zeppelin; 11-01-2008 at 02:08 PM.

  3. #3
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    Default Re: Shark Buck

    I would assume that you can also change the sense resistor to give a lower output? Say 700mA?
    Also, as LED Zeppelin asked, when will it be available.

  4. #4

    Default Re: Shark Buck

    Any value of sense resistor can be put on as long as the max current is less than 3A.

    The formula for computing the sense resistor is

    0.1 / Rsense = MAX_CURRENT.

    or

    0.1 / MAX_CURRENT = Rsense

    A 0.12 ohm resistor will give you 833mA, a 0.15 ohm resistor will give you 666mA.

    Valid resistors are E12 values.

    I have 10 that I have built by hand and have fired them all up and verified they work.

    I will try to get them online this week. Depending on how the 10 move will determine any future builds. I'm pretty certain this is a real winner and will move into production. Then again, who knows...

    Wayne

  5. #5
    Flashaholic* LED Zeppelin's Avatar
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    Default Re: Shark Buck

    Great Wayne, I'll keep an eye out and order several.

  6. #6
    Flashaholic* Nanomiser's Avatar
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    Default Re: Shark Buck

    Hi Wayne,

    I'm in the process of trying to figure out how to drive seven SSC P7s in series. What is the max Vin for the Shark Buck? What would you suggest?

  7. #7

    Default Re: Shark Buck

    Quote Originally Posted by Nanomiser View Post
    Hi Wayne,

    I'm in the process of trying to figure out how to drive seven SSC P7s in series. What is the max Vin for the Shark Buck? What would you suggest?
    Seven! Whoah, that's 70+ Watts of power (at 3A). The Shark Buck max input voltage is limited to ~25V. You could drive maybe 4 with that voltage. Two drivers one with 4 P7s and one driving three might work.

    I hope you have a large heatsink for all those LEDs.

    Wayne

  8. #8
    Flashaholic* Nanomiser's Avatar
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    Default Re: Shark Buck

    I hear ya Wayne! it's a lofty goal, but I think I have the heatsinking covered. Meet the Mammoth, H22A's creation. It should also have plenty of room to accomodate two drivers. I'm not looking to cut any corners on this one so a healthy investment in the driver department is justified. Would the drivers be wired in series to the supply?





  9. #9

    Default Re: Shark Buck

    There is another solution.

    You could use 3 Blue Sharks and drive all seven with the three drivers. Each Blue Shark would provide maximum of 1A for a total of 3A for three drivers.

    One Driver could be the master with a control pot or Remora and the other two could be slaved to the first for full control.

    For the buck configuration each driver is wired to the batteries seperately and drive their respective LEDs independant of the other driver.

    They could still be controlled together, one master, one slave.

    Wayne

  10. #10
    Flashaholic* Nanomiser's Avatar
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    Default Re: Shark Buck

    Hi Wayne,

    That sounds like a good solution! I just need to see if I will have the real estate for all three of these drivers. I'm assuming this tri-boards configuration could be made into a sandwich type foot print or do they all need to have their own independent heatsink?

    Thanks,
    Mike

  11. #11

    Default Re: Shark Buck

    I did some simulations yesterday and discovered why the Remora doesn't PWM throttle to zero like it should.

    It is correctable and I believe some small modifications it can be fixed.

    The fix on the Shark and Blue Shark I will document soon. For the 10 Shark Bucks I have now they behave like the Shark does.

    The production Shark Bucks I will incorporate the filter network onto the board and it will make the modification easier.

    I need to see if the fix even works and I will test it and post on the results.

    Wayne

  12. #12
    Flashaholic* LED Zeppelin's Avatar
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    Default Re: Shark Buck

    Wayne, do I understand correctly in that you have found a way to make all Sharks attain a lower low level than the current Shark/Remora? That would be great news and make the Remora more widely used IMO.

    Hopefully the fix is something I could implement on the stock of Sharks I have, or perhaps could be retrofitted by you.

  13. #13

    Default Re: Shark Buck

    Quote Originally Posted by LED Zeppelin View Post
    Wayne, do I understand correctly in that you have found a way to make all Sharks attain a lower low level than the current Shark/Remora? That would be great news and make the Remora more widely used IMO.

    Hopefully the fix is something I could implement on the stock of Sharks I have, or perhaps could be retrofitted by you.

    I know the simulation works. Whether I can rework both the Remora and the Shark has yet to be done. There is one "Ummm...." that may or may not work.

    Wayne

  14. #14
    Flashaholic* starfiretoo's Avatar
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    Default Re: Shark Buck

    The Mammoth builds are using 8 lithiums in series. Max voltage needs to be about 35 volts for the components. Do you have any buck converters that are rated that high?

  15. #15
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    Default Re: Shark Buck

    Hey starfiretoo,

    What are you going to put in your Mammoth? Would running 7 Li-ions plus one dummy work? That's probably what I am doing.


  16. #16

    Default Re: Shark Buck

    I would like to have one of the BuckSharks.

  17. #17
    Flashaholic* Aircraft800's Avatar
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    Default Re: Shark Buck

    This sounds exactly what I need for my 2C Mag P7's, the imported buck driver I have shuts down after a few minutes on high, now for some quality products!

    Thanks Wayne!

  18. #18

    Default Re: Shark Buck

    I have 8 converters to put online. One or two max per customer.

  19. #19
    Flashaholic* LED Zeppelin's Avatar
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    Default Re: Shark Buck

    Thanks Cindy, order placed.

  20. #20
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    Default Re: Shark Buck

    Ordered 2 online.

    Thanks Wayne and Dennis!

    Shark & SharkSink are perfect match. My favourite driver board.

  21. #21

    Default Re: Shark Buck

    Order placed.

  22. #22

    Default Re: Shark Buck

    SWEET!!!!

    I have a build that is need of one...or more of these

    Thanks again!!!
    Flashlight Modifications available upon request
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  23. #23
    Flashaholic* Gryloc's Avatar
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    Default Re: Shark Buck

    dat2zip,

    Could you state all of the specs for this new Shark Buck? I am very interested in the driver, but I wanted to know the min and max input and output voltages. Is there a maximum current that the Shark Buck can input, and can the output current be tweaked any above 3000mA? It would be neat to use two or three P7s in series operating (with a potentiometer or set resistor values) from an automobile (with proper protection circuitry, obviously). Thanks.

    -Tony

  24. #24

    Default Re: Shark Buck

    Quote Originally Posted by Gryloc View Post
    dat2zip,

    Could you state all of the specs for this new Shark Buck? I am very interested in the driver, but I wanted to know the min and max input and output voltages. Is there a maximum current that the Shark Buck can input, and can the output current be tweaked any above 3000mA? It would be neat to use two or three P7s in series operating (with a potentiometer or set resistor values) from an automobile (with proper protection circuitry, obviously). Thanks.

    -Tony
    Since this is a Buck input current is never more than the output current. For a 3A configuration the highest input current is near 3A when Vin = Vout.

    As long as Vin is higher than Vout you can use multiple LEDs in series on the output as long as the total Vf is less than the input voltage.

    For an automotive application two P7s should be fine with one Shark Buck.

    3A is tops for the Shark Buck as offered on the Shoppe. The IC could theoretically go up to 4A I would not recommend it.

    Minimum input voltage 3V. (Recommended to stay above 4V)
    Absolute Maximum Input Voltage: 25 (Recommend max 24V)

    For an auto application you should add the standard input protection for surge, reverse battery protection and any other protection required. Surge used to be a voltage spike of 60V. Not sure what todays specificatiosn are. I found a tester that would be used to simulate a surge condition http://www.noiseken.com/english/equip/img/ISS7600E.pdf

    A minimum input protection is a 3A diode and a 18V Transorb for a 12V automotive battery system.

    Wayne

  25. #25
    Flashaholic* Gryloc's Avatar
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    Default Re: Shark Buck

    Thank you for the reply, Wayne! It is getting late (oh, early) and I will try to finish digesting your post tomorrow to see if I have any questions. I had some TVS diodes (to suppress spikes), but I cannot be 100% sure if I picked the components with the right ratings. You listed some parts that I will have to look up and research more later on. Thanks for that.

    I love the new Shark Buck. I will definitely have to re-design some projects around it! I asked about absolute max ratings mostly out of curiosity. I guess that there isn't too much of a need to push a P7 or a parallel wired MC-E past 3000mA.

    -Tony

  26. #26
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    Default Re: Shark Buck

    Wow!

    This opens up a whole new range of possibilities.

    Following closely.

    -Michael

  27. #27

    Default Re: Shark Buck

    I added the wiring diagram to the product page.

    The feature image is:



    The wiring diagram is nearly the same as the Shark. Note that LED- is no longer common ground.



    As with the Shark you can parallel more than one Shark Buck to increase the output drive level. Two Shark Bucks could then drive up to 6A of output current and if both had one common pot would control regulation from full off to full on (or nearly full off).

    Wayne

  28. #28

    Default Re: Shark Buck

    So one Shark Buck should be able to drive 4 x P7's in series as long as the input voltage is higher than the VF of the emitters?
    Flashlight Modifications available upon request
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  29. #29

    Default Re: Shark Buck

    Quote Originally Posted by dat2zip View Post
    Seven! Whoah, that's 70+ Watts of power (at 3A). The Shark Buck max input voltage is limited to ~25V. You could drive maybe 4 with that voltage. Two drivers one with 4 P7s and one driving three might work.

    I hope you have a large heatsink for all those LEDs.

    Wayne


    Nevermind...I'm a dummy and need to reread before asking questions.

    Got the Shark Bucks today and should have 4x P7's running in series soon.

    Thanks again for making great products available to us!
    Flashlight Modifications available upon request
    "I have to go return some video tapes." -Patrick Bateman



  30. #30

    Default Re: Shark Buck

    DaFABRICATA,

    Yes, that is correct as long as your fresh battery state (worst case) is 25V or less.

    (But, That is the IC max voltage rating (25V) and the capacitors voltage rating (25V) and pushing everything to the limits could be trouble. Normally, it would be best to be conservative and operate below absolute max ratings).

    Wayne

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