QB288 and QB304 offer very similar performance. Both use latest S6 Flux bin Samsung 561C. QB288 was developed for compatibility with more popular 54V DC CC LED Drivers. QB288 has lower diode count and lower cost compared to QB304.
With 300V rated connectors QB288 allows up to 4 boards to be connected in series. With QB304 up to 2 boards can be connected in series. QB304 has a higher diode count so it can handle higher wattage better and offer slightly more efficiency than the QB 288
|Total Number of diodes||288||304|
|Number of Diodes in single circuit||18||38|
|Number of parallel circuits||16||8|
|Absolute Maximum Wattage||159 Watts||179 Watts|
TIM such as paste and pads are Not Required when boards are used on flat surface like aluminum sheet or Slate series heatsinks.
Pan head, button head, round head, and truss head screws work fine. Flat head and oval headscrews or other screws with an angled surface should not be used.
If you use a washer, ensure that the washer does not have any contact with any Electrical test points highlighted in red circle. This is to ensure there is no short circuit failure.
As temps go up the Vf of diodes go down. When Vf does down the diode is able to pull more current. This can cause thermal runnaway in parallel boards circuits if 1 or more boards fail or get disconnected.
1) Use a Meanwell Type A driver if you wire Boards in parallel. Type A driver 54V or under have a Vf adjustment on driver. You can fine tune to limit the voltage. A voltage set at 53V or 53.5V instead of 54V can help avoid runaway.
2) A good thermal design can help. Heatsink can keep the board cool an ensure the voltage of diodes does not go down too much if temperature goes up.
3) Use fuse for each board or thermal cutoff switch.
Acrylic Sheet can be installed to cover the QB Board. Lamp will run a few degrees warmer. New Slate 2 series comes with M3 mounting points to install Acrylic Sheet. Tested with 0.08 in Clear Acrylic Sheet installed on Slate 2 double with 2x QB running at 250Watts. Acrylic Sheet was cut with plastic cutting knife.
Top: Without Acrylic sheet. Bottom With Acrylic Sheet installed.
Board uses Molex Lite-Trap connector 104188-0110 rated max 300V AC (RMS)/DC and 9A with 18 AWG wire.18-24 AWG Solid (recommended) or 20-22 AWG Strand Wire.