Power and LEDs

Connecting Monochrome LEDs

Note that one leg of the led is longer than the other. This is the Anode and should be connected to the V+ hole in the board.

Off-Board Mounting

For more flexibility in positioning LEDs, you will probably want to connect your LEDs with wire instead of soldering them directly to your breakout board.

Our Pig-Tail Cables make remote mounting of individual LEDs very simple.

You can also install headers onto the PCBs, then plug the pig-tail socket there, and solder the LED legs to the wire ends - whatever makes sense for your project

Tip: One strand of the pig-tail is marked in gray. Solder this to the V+ side to mark the polarity.

Connecting RGB LEDs

Output channels are conveniently arranged in groups of 3 to simplify connecting RGB leds.

The common anode (longest lead) should be soldered to one of the V+ holes (any one will do)

When working with a breadboard, connect V+ to the bus on the edge of the breadboard and plug the anode into the bus.

Multiple LEDs in Series

The wide voltage range and constant current drive makes it simple to drive multiple LEDs in series from any channel. Just be sure to choose a supply voltage is higher than the sum of the Vfs of all the leds in series.

For example: To drive 5 blue LEDs in series, you would need at least 3.2v * 5 = 16v. This voltage is within the range of either the TLC59711 or the TLC5947.

Powering your LEDs

For running as many as 8 channels of RGB or 24 channels of single LEDs, you can usually get by borrowing power from the Arduino as shown. If you plan on running more LEDs with these boards, you should start thinking about how to power them.

Constant Current

Both the TLC59711 and TLC5947 are constant current drivers. This is just what LEDs need. Since they are constant current, you have some flexibility with the supply voltage and you don't don't need to add current limiting resistors. The TLC59xxx drivers will adjust automatically to power supply fluctuations. Your LEDs won't flicker and you don't have to worry about burning them out. We have configured these breakouts to set the current level at 15mA per channel. This is a safe level for virtually all leds you might want to connect to them.

To operate at different currents, it is possible to replace the on-board reference resistor with a through-hole resistor. These drivers are capable of driving up to 60mA (TLC59711) or 30mA (TLS5947) per channel. The graphs in the data sheets show the relationship between resistance and output current.

TLC59711 Data Sheet
TLC5947 Data Sheet

Choosing a Supply Voltage

Since these are constant current drivers, the voltage selection is not so critical. It just needs to be slightly higher than the forward votage (Vf )of your LEDs.

Supply Voltage Range:
  • TLC5947 - 5v to 30v
  • TLC59711 - 5v to 17v
Typical LED Vf by Color:
  • Red 2.1v
  • Yellow 2.2v
  • Green 3.2v
  • Blue 3.2v
  • White 3.2v

Connecting an External Supply

If you do decide you need an external supply for your LEDs:
  • First remove the connection between V+ and VIN from the Arduino.
  • Be sure to keep the connection between GND and the Arduino GND.
  • Next connect the negative terminal of your supply to GND on the breakout.
  • Finally, connect the positive terminal of your supply to V+ on the breakout.
This guide was first published on Dec 06, 2013. It was last updated on Dec 06, 2013. This page (Power and LEDs) was last updated on May 04, 2015.