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Shark Buck

Gryloc

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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
 

dat2zip

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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
 

Gryloc

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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
 

dat2zip

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I added the wiring diagram to the product page.

The feature image is:

sob_buck_features.jpg


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

sob_buck_wiringdiagram.jpg


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
 

DaFABRICATA

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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?
 

DaFABRICATA

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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!:thumbsup::wave:
 

dat2zip

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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
 

DaFABRICATA

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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



Email sent....
 

dat2zip

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I've got some news for all those that bought one of the current Shark Buck converter boards.

One report came back with a blown converter after a few minutes of running. I have setup a bench test and have confirmed the converter overheats. It appears the copper foil thickness is standard 1oz copper trace and not the 2oz I ordered. I have a previous version that has 2oz and it runs fine with the simulated quad P7 load and with 20V input.

The overheating resembles bench testing I did on the Shark and the Blue Shark.

If you have not hooked up the Shark Buck I can send you a replacement when the next batch comes in which should be this week sometime. I will test one and verify the production batch is good before they go out.

I bench tested all 10 of the current ones momentarily (wired for 1A) and didn't see the thermal issue. I had tested one at 1A for extended periods and did not test them when I upgraded them to 2A or 3A.

If you want to give the current one a go let me know if you successful or if it blew. I'll replace it if it blows.

It took me a while to make the test load. I wired up 16 Lux3 as four groups of four LEDS to mimick a quad P7 setup. The Vf @ 2A was around 12V or so.

I'll post an update when I get hold of the production boards. Sorry about this.

Wayne
 
Last edited:

dat2zip

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OK,

Looking under the microscope of the two boards I can definitely see the previous version has thicker traces than the ones just made and shipped.

So, I can say for certain 1-2A is about tops as that is where the Regular Shark ran successfully which is the same IC on 1oz process.

If you are uncertain I will be happy to send a replacement ASAP assuming the panels in production are 2oz copper. Otherwise, we have a big problem.

Wayne
 

LED Zeppelin

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Wayne, thanks for the heads-up.

I haven't hooked mine up yet, but will be using them with a 3A load, so I would like to have them replaced when the new batch arrives. Should I send back the ones I have?

Were you able to sort out the PWM throttling on the upcoming boards?
 

dat2zip

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Wayne, if I attach my old batch Shark Buck to a Shark Sink, will I be okay running 3A?

No, that won't be ok. It doesn't matter what size heat sink you attach the Shark Buck to as the IC is not able to transfer the heat away to the bottomside. The fix is thicker copper on the PCB.

You can remove the 0.1 ohm resistor and make it a 2A version.

Wayne
 

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