BICOLOR LED Confusion

Hello!!!

Another newbie question here...

I haven't used bicolor LEDs before, so I've read some, and found out there were basically two kinds: the 2- and 3-legged kinds. I understand that in order for the 3rd color to come out (the combination of the original two), you have to drive the 2-legged kind by alternating the current direction through the device really fast (cause you turn on one color only, by letting current pass through in a certain direction).

But this datasheet got me confused, because I know that 3-legged bicolor LEDs have a common something (anode/cathode), and thus, you can turn on both LEDs at once.

**broken link removed**

This datasheet (it's of the 3-legged kind) says you have to PWM both colors/LEDs. But why??? Can't you just turn on BOTH LEDs so you can get the third color?...

Thaaaaaaaanks!!! =D

This datasheet (it's of the 3-legged kind) says you have to PWM both colors/LEDs.

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No. It literally says

Colors between the two chips can be generated by independently pulse width modulating the LED chips.

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The difference is betweeen "have to" and "can".

PWM is in fact often used for this kind of bicolor LEDS. But you can also use a static current ratio, and the datasheet doesn't opt against it.

You can apply a constant current to one or both sides of the LED and get 3 basic colors (LED1, LED2, and LED1+LED2). If want to vary the shade and/or the intensity of the colors, you can apply a PWM current.