The 120 Hz I have found as minimum refer to the frequency that make the last 2% of the people not see jitter is for the TOTAL cycle. So if you multiplex by column (40) the multiplex must take place at 5000 Hz.

Another aspect that I see somewhat missed is that the effective LED current is I/refresh rate. Ehigie talk about 5mA and with column MXP that would power the LED by an effective ~.1 mA which would not show much intensity.

I have not noted the number of rows stated, so I calculkate by columns, but with row MPX the math is the same.

In our business we have given up totally on multiplexing for amber signs, the overhead is extremely restrictive.

Where I can drive a non MPX amber sign with any old '51 derivative, I need a 100MHz SILabs to process the colors. Processing colors require upload of new data for another unblank width saveral times per cycle.

Erik