Created by Kevin Culkins, last modified by Robert Nelson on Sep 08, 2017
DKSB1003A LM3406 LED Driver Evaluation Board
Features
- 3 user selectable LED constant current drive levels
- Input voltage range 6V-75V
- External connections using solderless terminal blocks
- Dimming pin brought out to solderless terminal block for easy access
- Output open-circuit protected
- Small board footprint
Quick Start
Connect DC power to TB1-VIN (6V – 75V) and ground to TB1-GND. Attach LED anode to TB2-LED+ and cathode to TB2-LED-. Remove jumper from header J1 for a regulated output current of 360mA.
Functional Description
The DKSB1003A LM3406HV evaluation board provides a means of evaluating the LM3406HV over its operating voltage range at user selectable LED drive currents. Output drive current options of 360mA, 750mA, and 1.5A are jumper selectable. Solderless terminal block connections are provided for power-in, constant current out, and dimming control. The power-in and ground connections are made at terminal block TB1, labeled on the board as VIN and GND. The LM3406 DIM pin is brought out at TB3-DIM. TB3-V+ and TB3-GND are connected to TB1-VIN and TB1-GND respectively, and can be used to power user supplied dimming circuitry.
Jumper J1 determines the output current by changing the sense resistance. With the jumper removed, the LED drive current is 360mA, with R3 being the singular sense resistor. A jumper positioned across header pins J1-1 and J1-2 parallels R2 with R3, providing an LED drive current of 750mA. Repositioning the jumper to J1-2 and J1-3 parallels R3 with R4 for a LED drive current of 1.5A.
The evaluation board is not optimized for any particular input/output combination. Various design characteristics can and should be optimized for a specific application. Refer to the Texas Instruments LM3406 datasheet for information regarding component values for a particular application. Another source of information is Texas Instruments Application Note 1750.
Schematic, Board Layout, BOM
DKSB1003A Eval Board.pdf (333.4 KB) includes text above, schematic, board layout, and BOM
Errata
The following evaluation board errata apply only to DKSB1003A LM3406HV LED Driver Evaluation Board (there is no revision marking on this version of the board).
- LED or LED string doesn’t dim smoothly using the PWM input.
Details: Output capacitor C4 is connected to the Anode of the LED terminal and Ground. This may cause dimming problems when using the PWM input terminal and exhibited as a pulsing or strobe effect of the LED or LED string.
Work around: Two options are available.
Option One: Completely remove capacitor C4. This option will see an increase in ripple current at the output.
Option Two: Reposition C4. Repositioning C4 will connect C4 to the anode and cathode of the LED load. This option will result in less ripple current at the output. Figure 1 identifies C4 in its original position and Figure 2 shows C4 after repositioning.
Figure 1. C4 Original Position
Figure 2. C4 Repositioned
NOTE: Several boards of the last production run have been reworked with C4 repositioned. To determine if your board has been modified, visually inspect the board and compare to Figure 1 and 2 above.