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Blue Shark is the new, cooler version of the Shark. Takes a big bite out of driving multiple LEDs in series. Great for use in flashlight and fixed lighting applications.
Size: 0.750 inch(19.1mm) diameter
Note: Blue sharks shipped after July 18, 2010 will have the 2 diode modification. All Blue Sharks shipped before this date may have thermal runaway with input current over 2.5A.
Specifications:
- Input voltage range: 2.7V - ~25V (Vin < Vout)
- Maximum IC switch current: ~4A (input ~3.2A)
- Output Current: Adjustable on board trim pot - 50mA - 980mA
- Output Voltage: ~32V
- Regulation: Voltage or Current.
- Maximum component height 3mm
- Raises Vout from 22.5V and improves thermal performance over standard Shark
- Requires Heatsinking
Optional:
- Remove trim pot
- Change sense resistor for max output current. (standard 0.1 ohm = 1A. 0.12 = 0.833mA, 0.15 = 666mA)
- Change output capacitor (to reach ~32V)
This will put open circuit Vout to ~32V and provide no load protection. 3-7 Lux3s/Cree XRE/Seoul P4s can be driven with this configuration as long as the boost input current does not exceed 3-4A. You can drive 5-6 Lux3s in series with 9V - 12V input and drive the string at 1A.
For 4-die LEDs:
ie.: One Blue Shark can drive 2 Cree XM-L with a upgraded output capacitor configuration >25V. See option.
Do not wire the converters in series. You can use one Remora with 2 Blue Sharks.
The Blue Shark has better thermal properties and heat dissipation. It runs cooler. Comes with the copper C installed.
The Blue shark will work with the Remora too.
The trim pot can be removed and an external 20K pot can be hooked up allowing control of the
converter board. The trim pot input can also be PWM controlled via a microprocessor.
To thermally bond Blue Shark or Shark Buck to a heat sink, use a super thin (paper thin or thinner) layer of thermal glue.
When mounting a Blue Shark, Shark Buck etc to the heat sink use an ultra-thin layer of adhesive for maximum conductivity. Too thick of a layer is like creating an air gap.
For proper mounting the converter board should be clamped. Thermal interface to heat sink must be less than 15C/W.
Arctic Alumina Thermal Adhesive (2 Part Epoxy)
Arctic SILVER Thermal Adhesive 7g set
Arctic Alumina Thermal Adhesive (2 Part Epoxy) Medium Cure
** 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. **
Add a note in comments specifying resistor(s) want to change.
Shark FAQs here.
Questions and Answers on CPF
Testing set up on CPF post #378
The technique I use to test the converter board safely should be done prior to any hookup to ensure the converter is fully functional.
Most boards shipped mid this year or so have been pre-tested. Still, pre-tested or not I would still test it before using it.
The ideal method for the Shark buck is the use a power supply set at 6V with the current limiting set to 150mA or so. At this current
there is little risk in damaging the converter board even if there is a problem.
Wire the converter board to the power supply and an LED. Any standard 1W,3W LED with Vf around 3.2V will be fine for this test.
Apply power. If the LED lights and the power supply current limits turn the trim pot till the power supply comes out of current limit. Verify the trim pot adjusts from near zero LED brightness to something brighter until current limiting is reached. If there is control over this range the converter is fully functional.
The same test setup can be used to safely test the Blue Shark except the LED load needs to be three LEDs in series. Again after power is applied the LEDs should light up and you should be able to turn the trim pot to get the LEDs to goto near zero light output and have some brightness control range up to the point the power supply current limits. If this work you can raise the current limit to 300mA and verify control over a larger range.
If you don't have a power supply the next best thing is to use something like a 10-20 ohm 2W power resistor in series with a 6V battery pack. The 40 ohm resistor should provide enough protection even if the converter is shorted.
Warning: Always make sure the max current is never exceeded from a fresh battery to fully depleted battery condition. |
