I need a little assistance sorting a couple of things out. I want to build an LED scoreboard and I am trying to figure out the circuitry to actually drive the LED's with a MAXIM 7221 Display Driver. It's a pretty straightforward problem with smaller 7 segment LED's because they don't require a higher voltage than the MAX7221 can display. But I want to use larger (2.3") LED's for my display for visibility. There is an app note for the MAX7221 that describes a circuit for driving higher voltage displays from the MAX7221 but it's not clear to me if I need 1 of the circuits or 2. First, here's some info http://datasheets.maxim-ic.com/en/ds/MAX7219-MAX7221.pdf" http://www.maxim-ic.com/app-notes/index.mvp/id/1196" http://www.futurlec.com/LED/7SR23011BS.shtml" [Broken]. I'll try to outline what (I think) I know and hopefully someone can tell me if I am thinking correctly. 1) The datasheet for the MAX7221 specifically addresses driving a 2.3" LED (on page 10) but seems to ignore the fact that the LED requires 8V. 2) The app note addresses using the additional circuits to drive higher voltages and/or currents than the MAX7221 can provide, but I don't think I fully understand the implications of the app note. Here is what I am thinking... a) I need to drive higher voltage LED's. I can use the circuit if FIG 3 of the app note with a 9V supply to get the desired voltage to the anode. b) Because the LED forward current is only 25mA, I don't need to boost the current to the segment drivers (as shown if FIG 4 of the note) (Is this correct?) c) Because I am using the circuit in FIG 3, I have to use a common anode LED instead ot the common cathode LED that the MAX7221 is designed to drive. (This comes directly from the app note). 3) I am not 100% clear on how the 7221 drives the LED's. Assuming a 5v LED that doesnt require additional driver circuits...The anode would be at +5V and the cathode at GND to light up a segment...now when a segment is turned off...does the anode go to GND or does the cathode go to +5v?