max number of TLC5940's

hi all, cant find any info on this. is there a limit to the number of TLC5940's you can connect together? does this have any effect on the grey scale resolution? ive got one working and ive looked at the mux stuff but was wondering if there was a limit (not including running out of memory possibly on the arduino)

I'm also interested to know this. I thought I had read somewhere in the datasheet that you could connect "up to 7"....??

There is no upper limit if you are prepared to buffer the Arduino ouputs enough. Look at the input current and capacitance specs for the chip's clock and latch inputs and work out how many an Arduino pin can drive. Arduino pins source/sink 20mA fine, I forget what total capacitance they can drive (this is also affected by the length of the wiring runs).

If worried buffer the signals. A MIC4422 will drive several amps and 100's of nF, for instance, or you can batch the TLC5940's into groups of 4 or 8 or so and have a CMOS buffer for the group, then each group looks like a single CMOS logic load.

Thanks MarkT useful stuff