The 3021 and 3023 BuckPuck LED Power Modules are a line of true current regulated drivers for powering LEDs. The BuckPuck line of LED drivers is the ideal...Read More...

Product Overview: The 3021 and 3023 BuckPuck LED Power Modules are a line of true current regulated drivers for powering LEDs. The BuckPuck line of LED drivers is the ideal choice for powering all types of highbrightness and high-power LED Packages and LED arrays.

The line of BuckPuck LED drivers exhibit high eciency and require no external current limiting resistors or additional heat sinking for operation. A fast response current-sensing circuit makes the 3021 and 3023 ideal for applications where ashing or strobe operation of the LED(s) is required.

A wide range of options are available including external dc analog voltage intensity control, TTL/CMOS logic level on/o control (”E” Version), and set-and-forget internal current limiting (”I” Version). The standard units are fully potted in an extremely small form factor* and are provided with a simple 7 pin SIP connection for through-hole PCB mounting (3021) or 6” 24AWG Colored Leads (3023).

The 3021 and 3023’s built-in regulated 5V reference (E and I versions) can provide output to power logic circuitry or microprocessor, eliminating the need for an additional power supply on the circuit board.

Application Information: The 3021/3023 Wide Range LED Power Module is a high eciency dc to dc converter which delivers a xed output current by varying the output voltage as required to maintain the specied current . A fast response current-sensing circuit permits the unit to be used in applications where ashing or pulsing of the LEDs is required. Several options are available allowing for use with many types of LEDs and in a variety of operating modes

Fixed Current Drive: The xed output versions of the 3021/3023 are designed to supply their rated current to one or more LED junctions. For example, a 350 mA rated unit will drive up to six white 350mA LEDs connected in series at 24VDC. Due to the nature of the buck regulator, the input voltage must always be higher than the total forward voltage drop of the LED junction(s) connected in series (2.5V for DC models, 4V for AC models). Thus, for a series string of six junctions having an average forward drop of 3.5V each, the required minimum input voltage will be 23.5VDC. A standard 24VDC power supply is a good choice for this application.

Figures 4 through 6 show 700mA and 1000mA rated units driving multiple LEDs. Note that parallel strings of LEDs can be driven directly with no additional circuitry required to ensure current sharing. The nature of the LEDs themselves will provide sucient current sharing if the parallel strings comprise of 3 or more junctions each.

Adjustable Current - On-Board Control - “I” Model: Where the ability to adjust the output current to an intermediate value is required, all output current 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:

Because there is a small, high-frequency component in the 3021/3023 output, many multi-meters may give anincorrect 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 rotations (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.

Adjustable Current - External Control - “E” Model: 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 5VDC reference (Ref) output and the control (Ctrl) input. When using this conguration, it is important that Vin be 7VDC or higher. Figure 11 shows the control potentiometer being powered by an external 5VDC source. When using an external power source for the potentiometer, the source 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.

External On/Off Control: Where a manual on/off 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.

External Pulse/Strobe Control: 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 4.75VDC 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.

Microprocessor Control: Figure 16 shows a typical interface for a Microchip PIC® or similar μcontroller. The reference output provides the operating voltage for the processor (5V at up to 20mA current).

Other Control Applications: In addition to the configurations described above, the 3021/3023 may also be driven by a D to A converter. As in the cases above, the analog control signal should have its ground common to LED-. Figure 2 shows the efective control range of the analog input signal.

Connections: In all cases, the LEDs being driven should be located as close to the 3021/3023 LED output as possible. When the use of long leads is required, use heavier gauge wire. For strobe or pulse applications, a wire length not exceeding 6" should be used to maintain accurate timing.

The power input wires/traces should also be kept short. Where DC input units are located more than 18" from the source, a 220μF, 50V capacitor should be placed across the input terminals as shown in Figure 18.

For applications where the use of header pins is inconvenient, a mating connector with 6" leads is available as an accessory, or the 3023 part number may be used, which is supplied with 6” colored leads.

Note: The above are product highlights and not the complete manufacturers datasheet. Please view the .pdf for complete specifications.