<< These devices are designed to operate with driver voltage drops of 0.4 V to 0.7 V with LED forward voltages of 1.2 V to 4.0 V. If higher voltages are dropped across the driver, package power dissipation will be increased significantly.

To minimize package power dissipation, it is recommended to use the lowest possible load supply voltage or to set any series dropping voltage (resistors) or a Zener diode, or a series string of diodes (approximately 0.7 V per diode) for a group of drivers.

For the devices I use (ST2221 and Rohm) I use a LED supply voltage of 3.3V for amber and 4V for color with no problems. The chips are surface mount with no cooling. One note, however, I have heard rumors that someone has problems with the 2221C which is 16 bits and thus twice the disappation (I only use the 2221A).

Erik