TASKLED - Smart LED drivers
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CCxW Technical Information
Potting Warning:
Areas of the circuitry on the CCxW drivers utilize high impedance paths and if potting (not required) is to be utilized, the user must ensure than the compound is non-conductive and non-capacitive otherwise correct operation may be compromised.
Hookup information:
The circuitry (all surface mount) fits neatly on a 1" x 0.8" PCB that can be glued directly to the backside of a Luxeon Star (1W). It is also capable of running from 4V up to 30V. The picture shows the latest V3 PCB layout that is being phased in as of Sep 2005. On the V4 PCB there is a thruhole (top left in the picture below) that is labeled On/Off. This pin when pulled to 0V will turn off the driver and it will draw <0.5mA. Maximum applied input voltage on the On/Off pin is 6V. If the On/Off feature is not require, leave it unconnected and the driver will remain on.
Connections:
D1 is the reverse polarity protection diode. If the application requires the lowest possible input voltage margin, then D1 can be shorted out - of course that will also remove the reverse polarity protection.
Below is a view of the 2nd Generation driver board that started shipping in March 2003. A Luxeon Star is mounted to the driver board using heat conducting thermal adhesive (http://www.arcticsilver.com). You can also see the two pins/tabs sticking out of the left and right sides. Those pins plug into the original 1 1/4" festoon light holder.NOTE: unlike the 1st Generation driver board, the back of the new driver board is NOT totally electrical neutral. Both the input and LED output power pads are also on the back of the board. If the board is to be glued down to a metal surface care must be taken to not short out the input/output pads. I have found that applying a thin layer of epoxy resin and then pushing the board down onto a piece of gladwrap type plastic works a treat. The epoxy sets up but will not stick to the gladwrap plastic. The thin layer of epoxy insulates the base of the board, and then it can be safely epoxied to a metal sheet like my I do on my maplight modules without any risk of shorts.
Another view of the 2nd Generation driver board, without a Luxeon or the mounting tabs. The 'mounting holes' are electrically neutral and can be used as necessary to attach the driver board.
Close up of the 1st Generation board. The first 220 boards were 1" square. The back of the board was electrically neutral - i.e. no connections to any of the circuitry. Also, the GND and +ve input thruholes have to be carefully used if a Luxeon Star/O is bolted to the back. The thruhole is not plated on the back side, but it is possible for a wire soldered into the thruhole to protrude too far and short to the back of the Luxeon Star/O.
Note: This is the 1st Generation driver board, phased out Mar 2003.
The assembled board connected to a Star/O with the lens unclipped. This is just for testing, for final assembly the Luxeon Star will be bolted to the back of the PCB. The driver board generated a constant current 350mA drive to the Luxeon drawing about 120mA from the 12.8V. It functioned all the way down to 3.8V drawing 335mA (with the protection diode D1 removed).
The following table shows the conversion efficiency of the circuit based on input voltage and input current. The efficiency was measured with a load resistor drawing 350mA at a nominal 3.55V. Note, protection diode D1 not in circuit.
Voltage (V) |
Current (mA) |
Efficiency |
20.37 |
80 |
76% |
15.87 |
100 |
78% |
14.23 |
110 |
80% |
11.73 |
130 |
82% |
9.47 |
160 |
82% |
8.14 |
183 |
84% |
6.60 |
220 |
86% |
5.42 |
252 |
91% |
4.62 |
296 |
90% |
4.13 |
330 |
90% |
The driver board as shipped is also capable of driving two series connected 1W Luxeons. The input voltage needs to be at least 8V for this configuration to maintain current regulation.
The driver board can also drive a 5W Luxeon, to do that several pin-compatible components need to be changed on the board.
You can find information about the Luxeon LEDs here: http://www.lumileds.com
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