20W RGB LED Driver Board Assembly (WS2811 version)

BOM

QTY    Part               Description
3      IC1,IC2,IC3        PT4115 constant current buck driver (soldered)
1      IC4                78L05 LDO
1      IC5                WS2811 (soldered)
3      L1,L2,L3           100uH inductor, 6x8mm, 500ma
3      T1,T2,T3           2N3904 transistor           
3      D1,D2,D3           1N5819 diode
3      R1,R2,R3           0.33R  resistor
3      R4,R5,R6           10K resistor
3      R7,R8              33R resistor
1      C1                 47uF/50V capacitor
1      C2                 0.1uF capacitor
1      C3                 33pF capacitor (optional, see bottom of this page)

UPDATES

New in v5: (all assembly pictures are v4, I will update them to v5 as soon as possible.)

1. Redesigned LED pads. The pads are now wider (and PCB is little shorter,) increasing possible offset of the LED to +/- 1/16". You can also solder LED without trimming it's leads. It will make connection point stronger, but it will make it more difficult to remove the LED (if it goes bad.)

2. Redesigned input pads. The pads are now bigger and the drill holes are larger (large enough for #18 wires.) There is no GND pour around pads and they extend to the edge, so you can solder wires horizontally if needed.

3. Added test points. Teat pads allow easy testing of the LED drivers. Just short GND test point with any of the remaining 3 test points to turn the channel on. (see below)

4. RGB color order pads. Just like in the 10W version, you can now choose the color order, GRB (default) or RGB. For RGB, solder transistors like on the image below. (see below)

5. Redesigned inductor pads. To better fit in all types of enclosures, inductor pads are now farther away from the LED and they are rotated 90 degrees. Installing inductors horizontally (if needed) is now easier.

Solder resistors

Use as little solder as possible.

Cut leads

Cut leads as close to PCB as possible.

Solder diodes

Pay attention to polarity, diode's cathode (stripe) should be on the left side of PCB, pointing towards the LED.

Solder monolithic capacitor, transistors, and LDO

Check markings on components, 78L05 is LDO (IC4,) 3904 are transistors. LDO and transistors should be soldered about 0.1" from PCB, total height should be ~0.3".

Solder electrolytic capacitor

Use PCB to bend capacitor's leads. Pay attention to polarity.

"-" lead should be facing 33R resistors.

Solder inductors

Inductors should be as close as possible to PCB. Apply pressure when soldering, heat for ~2-3 seconds, 2-3 times each lead.

Some inductors may have isolation sticking out on the bottom, trim if that's the case.

IMPORTANT: newer 20W cases have smaller dimensions and inductors will not fit vertically. If that's the case, mount inductors horizontally.

Prepare LED

Cut LED's leads as shown, try to keep them as long as possible (3 inner leads.)

Solder LED

LED should be mounted on the bottom. Use a lot of solder (and flood vias) to make pads stronger.

Pay attention to polarity and alignment. LED's anode should be close to 0.33R resistors (bottom side on the image.) "+" sign should be facing PCB (don't ask, markings are weird on those things :) .)

RGB mode

Starting with version 5 of the board, there two extra pads between T2 and T3, which allow switching bases of T2 and T3.

This is the default GRB configuration. T2 - green transistor, T3 - red

This is RGB configuration, move B3 to upper pad (near T3 & T2 labels) and B2 to lower pad.

Test pads

To test driver and LED section, short any of the RGB pads to the GND pad.

Flickering issue

If you experience flickering, attach 33pF capacitor (now included with the kit) between Din and GND