I am working on a project where I have to power a 5 meter long LED strip (https://www.sparkfun.com/products/12022) and 54 3.4V 20mA LEDs and control them all from an Arduino. My current idea was to have one 12V source for everything, direct power to the strip in parallel with a voltage regulator to 3.4 volts to power the LEDs. After that stage, everything would be controlled from the Arduino through transistors.
According to the datasheet, the strip is 300 20mA LED assemblies at 12V, bringing total power necessary to 6 amps to power it. The individual LEDs are 20mA each, and with 54 of them the power draw would be 1.08A. This would bring total consumption to 7.08A. Do I really need a +7.08A 12V power supply, or am I doing something wrong?