7 segment LED math

[SavannahLion]

I'm a little confused by the specs on double digit 7 segment displays(either Common Cathode or Anode, doesn't seem to make a difference).

I see that IF is usually around 20 or 30mA (I'm looking at blue) and spec sheets usually seem to imply that this is for all the segments combined. But ~25mA seems awfully low. Is it because the luminosity is crazy low compared to a single LED?

If I go the other way and say that ~25mA is for each segment, then that's +/-175mA (for each digit) getting pumped through. And that seems an awful lot too.

Any techies want to give me a hint? Remember, this is about 7 segment displays, not your ultra-bright single shots.

[Howard_Casto]

This is just a guess mind you, but I would say it's the oddly low value.  7-seg displays are designed to use less power because they are often in clocks and thus are always on.  I know I used to trace the pins on the ones that used to come in pc cases with a single AAA battery. 

Even if I'm wrong, hooking up to too low a voltage won't hurt while using the other could fry the thing. 

[SavannahLion]

That's what I figured. I pulled out my older red display and plopped them in and drove them for about two hours without frying anything. I don't have any specs on the ones I have but I figure they likely to be less effective the blues I'm expecting.