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MAX232: Interface MAX232IN

Antonio Arnone
Prodigy 30 points
Part Number: MAX232

Dear all,

I would like to know the maximum distance that the MAX232IN can transmit/receive. Furthermore, I would like to know if the unconnected pins should i life free or grounded.

Many thanks

Cordially 

Antonio 

  • 0
    TI__Mastermind 25705 points

    Antonio,

    The distance of communication is governed by the load. In general the test of speicifc data rate is conducted with 3kOhm resistance and 1000pF capacitance. If low capacitanc cable is used, longer distance could still work. For example, UTP CAT-5 cable has a typical capacitance of 17 pF/ft, thus the maximum allowed cable length is about 58 feet.

    For unused input pins, it's OK to ground them. For unused output pins, you can leave them open.

    Regards,

  • 0 in reply to Hao L
    Prodigy 30 points

    Dear 

    Thank you so much for your help.

    It is clear to me now. But, i need a bit of more help please. 

    Basically, I am connecting the 2 MAX232I between two Pics PIC16F1527-I/PT Master/Slave, Please could you help me to understand if i connect it well.

    By the way i connected them in this way. (Slave PiC)The Tx Pin coming to the PIC to Pin 11 MAX232I T1IN, The Rx coming from the PIC to Pin 13 Max 232I R1IN. 

    Then: The PIn 14 MAX232I T1Out i connected to be my transmitter signal to be connected to the master pic and Pin 12 the receiver signal to be connected to the master PIC

    Do you think is it right ? 

    Many thank 

    Antonio 

  • 0 in reply to Antonio Arnone
    TI__Mastermind 25705 points

    Antonio,

    Maybe I didn't fully understand the system setup. I think digital pins (TIN pin 11 and ROUT pin 12) should be connected to corresponding PIC port. Let TOUT pin 14 and RIN pin 13 to handle RS232 signaling.

    Regards,