©2012 LUXdrive, A Division of LEDdynamics, Inc. www.LUXdrive.com.
Specications subject to change without notice. March, 2012 - Rev 3.0
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LEDdynamics, Inc.
802.728.4533 P
802.728.3800 F
sales@LUXdrive.com
www.LUXdrive.com
Wide Range LED Power Module
3021/3023 BuckPuck
TM
DATA SHEET Page 4 of 8
Adjustable Current - On-Board Control - “I” Model
Where the ability to adjust the output current to an intermediate value is required, all output cur
rent ratings are
available with an on-board potentiometer. This permits the output current to be varied from approximately 40%
to 110% of the rated value. When measuring the output is required to determine a particular set point, the
following method is recommended:
Temporarily place a 0.1 ohm, 1% resistor in series with the LEDs.
Read the voltage across the 0.1 ohm resistor.
The voltage, in millivolts X 10, will equal the output current in mA.
Because there is a small, high-frequency component in the 3021/3023 output, many multi-meters may give an
incorrect reading when used in the current mode. It has been found that the method described above yields a far
more accurate measurement.
The potentiometers used for the on-board adjustable units are rated for a limited number of rotatio
ns (typically
100) and are intended for "set it and forget it" applications. Where frequent adjustments of output current are
needed, the use of units with external adjustment capabilities is recommended.
Figures 10 and 11 show external adjustment congurations. Both use a 5Kohm, linear taper potentiometer. In
Figure 10, the potentiometer is connected between the internal 5V
DC
reference (Ref) output and the control (Ctrl)
input. When using this conguration, it is important that Vin be 7V
DC
or higher. Figure 11 shows the control
potentiometer being powered by an external 5V
DC
source. When using an external power source for the
potentiometer, the so
urce ground must be common to the LED- output pin. In either conguration, connect the
potentiometer such that clockwise rotation increases the resistance. Note that, because the current through the
potentiometer is less than 5mA, a low power potentiometer may be used.
Where a manual on/o control is desired, the potentiometer in Figures 10 and 11 may be replaced by a pushbutton
or toggle switch. The output current will be zero when the switch is closed. Figures 12 and 13 show external
dimming control combined with on/o control. The circuit in Figure 13 uses a 2N3906 or equivalent PNP
switching transistor.
Figures 14 and 15 show two methods for low speed pulsing or high speed ashing operation. In Figure 14, a
5V TTL/CMOS logic signal is applied directly to the control (Ctrl) input of the 3021/3023. The output current will be
zero when the control signal is high. Note that the input needs to source a minimum of 4.75V
DC
into a 1.5Kohm
input impedance. Also, as is the case with a dc control signal, the logic input ground should to be common to the
LED- output terminal.
Figure 15 shows an inverted input conguration using a 2N3906 or other PNP switching transistor. In this case, a
logic high will cause the output to be "on". In either conguration, the rise time of the output will be 10μsec or
less. A pulse frequency up to 10kHz may be used.
Adjustable Current - External Control - “E” Model
External On/O Control
External Pulse/Strobe Control
