Poul-Henning Kamp said the following on 04/09/2006 04:07 PM: > In message <[EMAIL PROTECTED]>, John Ackermann N8UR writes: > > >>For what it's worth, the risetime of the MAX232 output is about 2.5us, >>in a very smooth ramp -- it's spec'd at 4 v/us. I have heard that the >>risetime is deliberately slow to match the RS-232 spec; I don't know >>whether that's true. The later version MAX232A is spec'd at 12 v/us; >>still not all that speedy. > > > It's mainly an EMI issue, if the flanks are too steep, kit fails the > EC mark test because they're too noisy. > > Since RS-232 is usually limited to around 110kHz max, there is no need > 4uS is a sufficient flank. > > Poul-Henning >
That makes a lot of sense. John _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts