Some questions about the Shark driver

[thegeek]

What's the absolute minimum input voltage that would be required for that? Edit: Is 1/3 the output voltage a hard and fast rule?

+1

Can an MC-E M bin wired in series (roughly equivalent to 4 Q5's in series) be run using the Blue Shark and 1 Li-Ion cell (provided the input current is kept within reason)? Most of this thread is about the green Shark, and the input current for that should be limited to ~2A, but what is a good upper limit for the input current on the Blue Shark?

Edit: Vf for led string would be 4*3.4=13.6 at 700mA, so output power would be 9.52W, guessing 80% efficiency gives 11.9W pulled from the batteries, so an input current at 3V of damn near 4A. On the page at the Shoppe it says not to exceed 4A, but I get the feeling that this is cutting it a little close.

For 600mA Vf is ~3.35, so we get about 10W from the battery again assuming 80% efficient, so ~3.3A. Is this bearable?

The crux of it is how much further can the Blue Shark be pushed vs. the green Shark?

[dat2zip]

+1

Can an MC-E M bin wired in series (roughly equivalent to 4 Q5's in series) be run using the Blue Shark and 1 Li-Ion cell (provided the input current is kept within reason)? Most of this thread is about the green Shark, and the input current for that should be limited to ~2A, but what is a good upper limit for the input current on the Blue Shark?

Edit: Vf for led string would be 4*3.4=13.6 at 700mA, so output power would be 9.52W, guessing 80% efficiency gives 11.9W pulled from the batteries, so an input current at 3V of damn near 4A. On the page at the Shoppe it says not to exceed 4A, but I get the feeling that this is cutting it a little close.

For 600mA Vf is ~3.35, so we get about 10W from the battery again assuming 80% efficient, so ~3.3A. Is this bearable?

The crux of it is how much further can the Blue Shark be pushed vs. the green Shark?

The upper end of the input current for the Blue Shark is at least 3A minimum with a possibility of 4A. I am comfortable with configurations where max draw is 3A - 3.5A. Beyond that the top of the IC and other components may need additional help on the topside. Beyond 2.5A the copper C to heatsink attachment is crucial and must be optimum.

Bench testing will determine your exact limits. If the converter heatsink is common to the bulkhead along with the LEDs the heat generated from the LEDs may limit the top end of the converter range.

Since the converter on the bench attached to a large heatsink and a fan blowing air across is the ideal or optimum, other configurations need to be tested to determine the actual barrier one will encounter.

There is no fast and set rule. A good bond of the converter to heatsink and if the converter heatsink is kept cool will ensure reaching the upper limits of the Shark or Blue Shark. Putting 24 Cree XREs and three blue sharks may in fact get hotter than a pistol and of course things may tend to shut down in short time.

When I say max current I'm assuming near dead battery voltage state. Not a fresh battery voltage or battery voltages where when fresh draw nearly max and get worse as the battery depletes. Always make sure the max current is never exceeded from a fresh battery to fully depleted battery condition.

The rule of thumb still applies where the full battery range (fresh to depleted) should be greater than 1/2 of Vf of the LED string.

Wayne

[thegeek]

Thanks for the help. That's exactly what I needed to know.

[mtnbkr1]

Should this configuration work?
11.1V li-ion battery pack (3 cells, rated 12.6v max)
One shark driver
2 MC-E's wired in series first, then in parallel.
With the shark set to max 1000mah, I should get 500mah to each string with is more than enough for me. Voltage at 500mah should be roughly 3.3v per LED, so I'm looking at 13.2v. Does the Vout of 13.2 versus Vin of 12.6 provide enough difference to maintain regulation? I guess where I might run into trouble is when dimming to lower levels when the batteries are fresh. At about 150mah current, I get about 3V per LED, which is only 12V. What will the driver do in this case?

http://www.cree.com/products/pdf/XLampMC-E.pdf

OR, and I better off putting the MC-E's completely in parallel, which at 700mah puts the operating voltage around 27.2V. I'm near the Vin=1/2Vout mark with a fully charged 11.1V and the batteries drop at 7.5-8V, so that's a bit below the 1/3Vout mark. I assumed the first configuration is more efficient.

Slightly off topic, can the 2 MC-E's be electrically tied to the same heatsink or does it need to be electrically isolated like some other LEDs?

[Jarl]

Slightly off topic, can the 2 MC-E's be electrically tied to the same heatsink or does it need to be electrically isolated like some other LEDs?

The slug of the MC-E is electrically isolated, so you don't have to faff like you do with P7's.

[mikespike2]

So with that CREE you have 4 led diodes in one package? Was I reading that paper right? That's bright! So do you have the option to wire them all in series/parallel or is it just two connections on the board?

[Jarl]

So with that CREE you have 4 led diodes in one package? Was I reading that paper right? That's bright! So do you have the option to wire them all in series/parallel

yup yup yup

You can get them mounted on PCB either series, parallel, 2s2p or independently addressable, unlike the P7 which is parallel only.

[bwilli]

Has anyone tried potting a Blue Shark?

I was dreaming up a project and would like to pot the board in some GC electronics potting compound. The copper C on the board would be AAE'd to the aluminum housing.

Thanks!

[Jarl]

Can the shark handle wildly changing output currents? I was thinking of rigging a pot and a momentary on switch- use the pot for variation between 50ma and 700ma, then with the momentary allow 1.5A current. Would the shark be fine going from 50ma to 1500ma and then back again in a short space of time?

[steve6690]

I'm not sure whether the Shark will give 1.5A output without some magic trickery involving resistor swaps. The thought of a "turbo" button is interesting though. I'm sure it could be done by switching in/out a parallel resistor with the operation of the button. I seem to recall someone changing a Shark's output to 1200ma by swapping resistors..this is only taking the concept a stage further. Whether the rest of the components will handle it is a question for Wayne

[dat2zip]

Can the shark handle wildly changing output currents? I was thinking of rigging a pot and a momentary on switch- use the pot for variation between 50ma and 700ma, then with the momentary allow 1.5A current. Would the shark be fine going from 50ma to 1500ma and then back again in a short space of time?

Using the control pin where the trim pot is hooked up to you can change output levels at some 200Hz or so.

That would mean changing the sense resistor so max is 1.5A.

Wayne

[snakeeaterhg]

Only that I get it right: if Vin ist higher than the Voltage of the LED String the Shark will work in direct drive but take no harm as long as the current is ok?

My concrete example (only rough values, not measured so far).

blue shark
8 x cree serial: 32V @ 1000mA
20V @ 50mA
6 x Lion serial: 25,2V full charge

If the sharc is set to 1000mA everything is fine, sharc boosts to 1000mA
Then I trim down the sharc to 50mA. Vin is too high, so Vin will be applied directly to the LED string and give me sth. like 400mA actual current. But the sharc takes no harm!!!???

[dat2zip]

Only that I get it right: if Vin ist higher than the Voltage of the LED String the Shark will work in direct drive but take no harm as long as the current is ok?

My concrete example (only rough values, not measured so far).

blue shark
8 x cree serial: 32V @ 1000mA
20V @ 50mA
6 x Lion serial: 25,2V full charge

If the sharc is set to 1000mA everything is fine, sharc boosts to 1000mA
Then I trim down the sharc to 50mA. Vin is too high, so Vin will be applied directly to the LED string and give me sth. like 400mA actual current. But the sharc takes no harm!!!???

Correct. Since the overdrive is not over 1A there is no harm at the low end overlap. I have done several projects very similar to this where low is higher than it should. No harm in this configuration.

Wayne

[steve6690]

Ok, I'm having problems with a blue shark. Basically it appears that it's not boosting ie it's in direct drive as input current matches output current. The trimpot seems to have a very slight effect only. Is my board fried ?

[dat2zip]

Ok, I'm having problems with a blue shark. Basically it appears that it's not boosting ie it's in direct drive as input current matches output current. The trimpot seems to have a very slight effect only. Is my board fried ?

That is possible if the board was not mounted to the heatsink well. If there is too much thermal epoxy between the copper C and heatsink it may cause the board to overload thermally and that would kill the IC. The two conditions of IC failure are supply short and open. An open condition results in a DD mode as you are experiencing. If the board has fried you can look at the thermal bond layer if you remove the board. Ideally, the thermal glue layer should be super thin (paper thin or thinner).

When mounting the board to heatsink visually inspect the bottomside and verify all leads are not protruding past the copper C and then clean and prep the copper C surface and heatsink of any contaminates and oxididation. If you can not clamp the board down you should still press down and twist back and forth to squeeze out make the thermal layer as thin as possible.

After mounting I would run the light for a couple of minutes and verify the tempererature on the top surface of the power IC to be within operating range. If heat is being thermally transfered correctly from the IC - copper C - heatsink the power IC temperature should not be over ~80C. If you see temps higher than 110C there is a good chance the thermal bond is less than ideal and could be cause for failure at some point in the future.

Pushing the board too hard may also cause the IC to overheat and fail. What batteries are you using and what type battery technology are the batteries and what is the LED configuration?

When did the Blue Shark fail? How long was the light on and what was the charge state of the batteries when it failed? Were the batteries nearly depleted when it failed?

Wayne

[Techjunkie]

Wayne,

In a Shark-with-Remora + Shark + Shark config, does the first Shark with the Remora have a trim pot, or is that one removed too? In other words, is it Remora OR pot, or is it Remora AND pot? Just a bit confused because the order page at the LED shoppe offers a fully assembled shark with remora with the option to remove the pot. I had previously assumed that the Remora replaces the pot, with high mode being the equivalent of the pot turned to max output (~1A per shark).

I'm planning to drive 5 parallel MC-E in series (5s4p) for a Vf of ~18v and an input range provided by 4 18650 IMR batteries from 10.4v-16.8v in using 3 sharks, one with remora. That works, right?

If I'm right so far, then I should order 1 blue shark fully assembled with remora and 2 blue sharks with pot removed?

Finally, do I have to modify the mag switch to remove the self cleaning feature to avoid a double click mode jump, or is that usually not a concern with the remora? Sorry for all the questions, I wasn't considering the remora until very recently. Thanks.

[dat2zip]

It is either Remora or trim pot. Not both.

All the slave boards must have the trim pot removed.

If I'm right so far, then I should order 1 blue shark fully assembled with
remora and 2 blue sharks with pot removed?

That is correct. One fully assembled and two with trim pot removed.

Finally, do I have to modify the mag switch to remove the self cleaning feature to avoid a double click mode jump, or is that usually not a concern with the remora?

I am not aware of any issues with the stock switch. There may be others who have more experience that can chime in on their experience or usage.

Wayne

[Techjunkie]

It is either Remora or trim pot. Not both.

All the slave boards must have the trim pot removed.



That is correct. One fully assembled and two with trim pot removed.



I am not aware of any issues with the stock switch. There may be others who have more experience that can chime in on their experience or usage.

Wayne

Wayne, thanks again. I've just ordered 3 blue sharks with trimpot removed, 1 remora board, and 3 shark sink D.

When I install the remora on the first shark, I bridge the top two trim pads on that one only, but not the other two, right?

[dat2zip]

Look at the first post. There is a table of contents for many different configurations and usages.

The one you want is called Remora + Shark + Shark.

Wayne

[Techjunkie]

Look at the first post. There is a table of contents for many different configurations and usages.

The one you want is called Remora + Shark + Shark.

Wayne

I'll take that as a yes. I just wanted to make sure that linked post was accurate, as it was presented as a question, not an answer. Thanks.

[Tortolita]

That is possible if the board was not mounted to the heatsink well. If there is too much thermal epoxy between the copper C and heatsink it may cause the board to overload thermally and that would kill the IC. The two conditions of IC failure are supply short and open. An open condition results in a DD mode as you are experiencing. If the board has fried you can look at the thermal bond layer if you remove the board. Ideally, the thermal glue layer should be super thin (paper thin or thinner).

I'm having the same problem as steve6690.
Had the blue shark clamped (little spring clamp) to heatsink with Arctic Silver. Checked for shorts and didn't find any. Applied 8.2 volts from 2x18650 and got 22-25 volts out (don't remember exact value) open circuit prior to connecting it to the LEDs (3 P4s in series with forward voltage 9.7 - 12 according to spec). Put my meter in current mode and put it between the driver and the LEDs to measure amps going through LEDs. Had the pot approximately in the middle so I wouldn't overdrive the LEDs (max forward current of 800 mA). LEDs lit up but meter read zero amps. Checked meter settings and connections, was plugged into 10A connector and set to 10A scale. Tried again, meter still read zero but LEDs lit up. Grabbed the heatsink/driver to move it and about burned my fingers the heatsink was so hot. Disconnected batteries and let everything cool off. Checked for shorts again, but didn't find any. Checked open circuit voltage with 8.2 and 3.0 volts in and get 8.1 and 2.99 out respectively.
I assume I must have done something, but what? Is there anything I can do to troubleshoot/fix the IC?

[dat2zip]

I'm having the same problem as steve6690.
Had the blue shark clamped (little spring clamp) to heatsink with Arctic Silver. Checked for shorts and didn't find any. Applied 8.2 volts from 2x18650 and got 22-25 volts out (don't remember exact value) open circuit prior to connecting it to the LEDs (3 P4s in series with forward voltage 9.7 - 12 according to spec). Put my meter in current mode and put it between the driver and the LEDs to measure amps going through LEDs. Had the pot approximately in the middle so I wouldn't overdrive the LEDs (max forward current of 800 mA). LEDs lit up but meter read zero amps. Checked meter settings and connections, was plugged into 10A connector and set to 10A scale. Tried again, meter still read zero but LEDs lit up. Grabbed the heatsink/driver to move it and about burned my fingers the heatsink was so hot. Disconnected batteries and let everything cool off. Checked for shorts again, but didn't find any. Checked open circuit voltage with 8.2 and 3.0 volts in and get 8.1 and 2.99 out respectively.
I assume I must have done something, but what? Is there anything I can do to troubleshoot/fix the IC?

You probably did everything correct. There is a known problem with this batch of blue sharks and pins on the IC not being soldered completely. Depending on what pins are not soldered different symptoms can occur. send an email to us and we will send you a replacement. I have been visually checking all of them and touching up any suspicious pins for over a month now. Depending on when you ordered you might have gotten one that was not screened. After screening the turn on rate rose significantly.

Wayne

[tx101]

Would I be correct in thinking that to increase the output current of a Blue Shark to 1.5A, the value of the sense resistors would be 0.05 and 0.10

From what I can see of the photos of the B/Shark, it only has 1 sense resistor ..... sorry for the noob question

[Tortolita]

You probably did everything correct. There is a known problem with this batch of blue sharks and pins on the IC not being soldered completely. Depending on what pins are not soldered different symptoms can occur. send an email to us and we will send you a replacement.

Received the new board (Thanks!) and hooked everything up again. Putting Vin from 2x 18650 (8.2 V no load), board clamped to heatsink, 3x Seoul P4 Natural White (Vf ~3.6, 800mA max) in series. Under load Vin=7.6v and Vout=10.7v. LED's light up very bright (only apply power for short (<2sec) bursts). The problem is that when I measure the current I'm reading ~1200mA with 2 different meters (with pot adjusted to minimum). Why isn't the current adjustable down to near zero? I planned on setting it to 800mA per LEDs spec.

[dat2zip]

See if one of the trim pots leads is not soldered. I would expect in your configuration everything should work as expected. If the trim pot has no effect then it might be the trim pot has a no connect on it.

I can't think of any other reason why the trim pot would have no effect.

Wayne

[mr_blinky]

I've just ordered a Blue Shark. It will power a Cree MC-E emitter wired in series. I intend to connect the Blue Shark to my own microcontroller. My goal is to make a programmable, "smart" strobe light. (Not a photographic strobe, but an Edgerton-style continuous strobe.)

Though I've read this thread in its entirety - and several others besides - I'm unclear as to how I should interface my microcontroller to the Blue Shark.

My understanding is that the analog pot serves as a voltage divider, and that the voltage from the wiper dictates the amount of current ultimately supplied to the load. The Remora replaces the analog pot, providing a PWM signal which replaces the "wiper voltage." Assuming this is correct, I understand how to do the same with my own microcontroller.

But I want to use my microcontroller to turn the LED completely off. I saw some reference to an "enable pin," which sounds like it might be what I'm looking for. Is there some spot on the Shark where I can apply/remove a control voltage to blink the LED at a rate of my choosing?

And what would be the fastest I could cycle the LED off and on?

Thanks in advance.

[Tortolita]

See if one of the trim pots leads is not soldered. I would expect in your configuration everything should work as expected. If the trim pot has no effect then it might be the trim pot has a no connect on it.

I can't think of any other reason why the trim pot would have no effect.

Wayne

The pot does have an effect, but I'm afraid to turn it all the way up with the LEDs in the circuit. The pins look soldered and I hit them with the iron just to be sure. What should the resistance be between the remora gnd and remora pwm vias (using labels from post 1 photos)? I get 45.8 to 50.9 K Ohm adjusting the pot from full clockwise to full counter clockwise. (On the first (bad) board I get 15.1 to 0.0 K Ohm.) Across the pot I measure 49.1 K Ohm on the new board and 15.1 K Ohm across the first (bad) board.

[dat2zip]

I've just ordered a Blue Shark. It will power a Cree MC-E emitter wired in series. I intend to connect the Blue Shark to my own microcontroller. My goal is to make a programmable, "smart" strobe light. (Not a photographic strobe, but an Edgerton-style continuous strobe.)

Though I've read this thread in its entirety - and several others besides - I'm unclear as to how I should interface my microcontroller to the Blue Shark.

My understanding is that the analog pot serves as a voltage divider, and that the voltage from the wiper dictates the amount of current ultimately supplied to the load. The Remora replaces the analog pot, providing a PWM signal which replaces the "wiper voltage." Assuming this is correct, I understand how to do the same with my own microcontroller.

But I want to use my microcontroller to turn the LED completely off. I saw some reference to an "enable pin," which sounds like it might be what I'm looking for. Is there some spot on the Shark where I can apply/remove a control voltage to blink the LED at a rate of my choosing?

And what would be the fastest I could cycle the LED off and on?

Thanks in advance.

The analog pin will control the output from 0 to 100% if done correctly. How the Remora was implemented did not give the full range of control.

To PWM the Blue Shark or the Shark Buck you will need to do the following.

The fixed resistor on the Blue shark that is part of the voltage divider for the Analog control should be used as the pullup to an open collector output from the microprocessor.

The open collector output should then have a voltage divider/filter to divide the PWM signal in half. This will be the proper signal level for the analog input. 100% on is 1/2 Vref. Zero volts is full off on the analog input.

PWM ---R----+----------+---- Shark Control input
Input       |          |
            |          |
            R          C
            |          |
            |          |
    GND-----+----------+

Wayne

[dat2zip]

The pot does have an effect, but I'm afraid to turn it all the way up with the LEDs in the circuit. The pins look soldered and I hit them with the iron just to be sure. What should the resistance be between the remora gnd and remora pwm vias (using labels from post 1 photos)? I get 45.8 to 50.9 K Ohm adjusting the pot from full clockwise to full counter clockwise. (On the first (bad) board I get 15.1 to 0.0 K Ohm.) Across the pot I measure 49.1 K Ohm on the new board and 15.1 K Ohm across the first (bad) board.

The value from Remora PWM and GND should be between 0 and 20k or less depending on the ohms range and multimeter type.

On the first board does it stay dim all the time? It sounds like there is no control if the resistance of the PWM input is near zero all the time.

When the PWM input is at GND (clockwise) there should be no output.

Make sure the LED Vf is actually three in series. Can you apply the battery to the LED string without the converter? Does it draw 1200mA in DD?

You could still draw current if the Vf is lower then Vin and then the converter would be in DD mode and there would be no control.

Wayne

[dat2zip]

The R, R, C components are already on the Shark Buck. You only need to add the 2nd R as it is not loaded or needed with the trim pot and is not needed when you use the Remora.

The Resistor value is 100k and the capacitor is 0.1uF.

Wayne