PartySystem/Power

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Delivering power to the LEDs turns out to be a somewhat difficult problem because they are all very high power. This page discusses potential power supplies for each type of LED.

Contents

RGB Panels & Rear Glow

The RGB chips have a common anode (terminal for positive voltage) and individual cathodes. Therefore, there is no way to drive these LEDs in series. A high-current, low-voltage power supply must drive everything. According to PartySystem/LEDs, the LEDs require 350mA @ about 2-3.2 volts. There are several simple power supplies we could build using the LM317T or LM338T linear regulators.

Constant Current Switching Driver

The TLC5940 is a constant-current PWM LED driver with 16 outputs capable of sinking 120mA per channel. These channels can be tied in parallel, so we can make 5 360mA super-channels. The chip is driven serially. Therefore, we'd need 4*3/5 ~= 3 chips per panel. No extra components are required. This is probably the best option.

See these app notes.

Constant Current Linear Driver

The constant current supply guarantees that each color of each LED is driven at no more than 350mA. It requires 1 LM317T and 1 3.6 ohm resistor per color per LED.

Pros:

  • Guarantees that each LED color is driven at 350mA
    • Safe
    • Better brightness consistency

Cons:

  • Requires 1 LM317T and 1 3.6 ohm (1/2W) resistor per color per LED = 96 of each for the panels and another 96 for the rear lighting.
    • Assuming roughly $0.71 for both (according to Digikey), that's a total of $68. However, we can use cheaper LM317's (500mA max instead of 1.5A max) from Mouser for $32/100.


Constant Voltage Linear Driver

Pros:

  • Would only require a few LM338T's since they're job is to maintain a constant voltage.

Cons:

  • Not a constant current driver
    • Potentially unsafe
    • Doesn't guarantee uniform brightness


Resistors

Requires strange resistor values with high power ratings. Just a bad idea.

Strobes

The white strobes are around 7V @ 750mA. We can wire these up in series and use high voltage boost drivers.

Blacklights

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