Hi David,
what do you use for converting to RS232 levels?

Regards,
Peter

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of David VanHorn
Sent: Wednesday, 23 June 2004 11:50 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [EE]: RS232 lines and EMC suppression


At 04:54 PM 6/23/2004 +1200, Richard Prosser wrote:

>Peter,
>1k might be a bit high given a "typical" RS232 load. Ferrite beads are more
appropriate but a 47 or 100ohm resistor should be OK. The cap could got to
10nF or so (with the 100ohms) , depending on the bit rate but 1nF would be a
reasonable starting point.  If you add too much capacitance you can get
caught by the series resonance of the cap itself.
>RP

Definitely beads for the high frequency emissions.

One reason I've avoided max chips, is that it's hard to get rid of residual
noise from the charge pumps. That frequency range is hard to filter without
large components, and affecting the output at 115200 bps.

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