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My company sells devices many devices that use RS-232 line transceivers like the MAX232 chip. In many cases our users run their RS-232 cables in the range of 30 to 50 feet to connect our device to their PC. Over the years we have seen many boards come in for repair because the serial communication stops working and the problem can often be fixed by simply replacing the MAX232 line transceiver.

My guess is that the long serial cable is acting as a giant antenna for EMI or static and the transceiver can only take so much. In our next board design we want to go with a surface mount chip which will be much more difficult to "pop-out" and replace if the problem occurs again. Is there a way that I can protect this chip against such problems without increasing the cost of the board/components greatly?

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  • \$\begingroup\$ Which package fries? Does it have pull-ups/downs? \$\endgroup\$
    – tyblu
    Commented Feb 8, 2011 at 21:11
  • \$\begingroup\$ It's the MAX232 chip that fries. It a DIP16 package \$\endgroup\$ Commented Feb 9, 2011 at 20:17

4 Answers 4

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You may want to consider a part with built-in ESD protection as a first-line of defense.

Maxim has a good application note on the topic.

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Add some EMI suppression filters.

Go to Murata, they have a wide range.

They also make ESD protection parts.

These days they come in surface mount too.

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You could try to use the MAX13223E that is Industry's First RS-232 Transceiver with Integrated ±70V Fault Protection Eliminates Need for External Protection.

see more in:

http://www.maximintegrated.com/en/products/interface/transceivers/MAX13223E.html

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A simple, although not cheap, solution is something like the ADUM1447 and its family members. I don't think you can top that.

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    \$\begingroup\$ That is not what digital isolators are for and they wouldn't work with RS232 anyway. \$\endgroup\$
    – Matt Young
    Commented Feb 26, 2015 at 20:33
  • \$\begingroup\$ Please see the datasheets for: ADUM1402 & ADUM5200 for example (among others). \$\endgroup\$
    – user34920
    Commented Feb 27, 2015 at 6:43
  • \$\begingroup\$ Ok,you found one that can isolate RS-232, still the wrong tool for the job. \$\endgroup\$
    – Matt Young
    Commented Feb 27, 2015 at 13:15
  • \$\begingroup\$ Can you explain why? \$\endgroup\$
    – user34920
    Commented Feb 27, 2015 at 13:45
  • \$\begingroup\$ As I already said, digital isolators are not designed for ESD and EMI protection. \$\endgroup\$
    – Matt Young
    Commented Feb 27, 2015 at 13:47

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