Electrical – Comparing MAX3232 vs MAX232 for line length

max232max3232rs232serialtransmission line

Which parameter in the datasheets of the line drivers MAX3232 and MAX232 can tell about the maximum length of the line for their correct operation if all else is same for the two circuits, that is baud rate = 115200, Vdd = 5 V, same UTP cable used.

Best Answer

100 ohm twisted pair is a poor match for rs232 drivers (which are about 1000 ohms) , the main limitation is the drivers capability to charge and discharge the line.

In my experience on long runs the main problem is dielectric absorbtion during the idle time causing the start bit to be distorted, this can be mitigated somewhat by fitting a diode at the receiver end to limit the negative voltage

So what you want most is low output impedance. voltage levels are less important.

Here the max3232's 35mA short-circuit current beats the max232's 10mA soundly.