LEDs hooked in series or parallel

jonw

Hi·········· ·I would like to make a seven segment display·with 5 leds. per segment·
···············Which of the connection methods, series or parallel is better.
········ I can handle Voltage and current requirements in both methods.
····················· · Thanks· jon

Post Edited (jonw) : 3/13/2007 3:20:42 PM GMT

Mike Green

There isn't a "better" way. With a series connection, you need only one current limiting resistor, but you need to be able to switch the voltage involved (5 x 1.7V = 8.5V) which shouldn't be a problem with a transistor switch (or the ULN2x00 Darlington array or something similar). With a parallel connection, you need a current limiting resistor for each diode and the total current is higher (5 x 10-20ma = 50-100ma). Both the total current (for parallel) and the total voltage (for series) are too high to switch directly from a microcontroller output, so you'll need some kind of driver in either case.

metron9

I would go with series for each segment. If you use a fet on the low side of each string and a multiplex PWM method you can use one resistor to the + side of all 7 strings as long as only one string is on at a time.

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