MAX7221 questions

my idea is to build a large clock with 7 segment displays, consisting of 4 4" displays and 2 2.3" displays, but now i have some questions about the max7221 i'm going to use, i recieved a few by sampling them from maxim.

on the playground page there is an table with what resistor to use with different voltages, but it won't go higher than 3.5v and i want to use these displays; http://www.futurlec.com/LED/7SR40011ES.shtml their forward voltage is 9.25v , is there a possibility of using these displays?

and another question, do you need only 1 max7221 to drive 6 displays or 6? i've got a bit confused because the pics on the playground page and different images on the internets.

their forward voltage is 9.25v , is there a possibility of using these displays?

Not gonna work. The MAX7221 has to power the display and it's a 5V device.

do you need only 1 max7221 to drive 6 displays or 6

The above aside, you would only need one MAX7221. According to the datasheet it can drive 8 seven-segment displays.

Yep the MAX7219/7221 is designed to run 6x 7-segment displays.

Here's my arduino clock running 6x 1" LED displays from futurlec

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1206916512/0

ok, thanks but is it possible to drive higher powered displays with these chips?

Not without starting to get complicated and use the outputs to drive buffers and transistors.

By that stage you may as well use a controller which is designed for higher voltages

i found a few displays on ebay from sure electronics based on some 74HC595 shift registers.
so, i think i’l choose them and learn a few things about shift registers in the process