Re: Protecting CAN Tcvrs

Hello,

You can first try so called CAN-protectors, which are dual-TVS devices in 
SOT-23. If power
of disturbance or worst-case failures is too high for such low-power 
devices, you can also
use SMB-size TVSs, but select them carefully - parasitic capacitance 
varies a lot between
the vendors.

But most important is to dampen the noise caused by the solenoids as close 
to them as
possible, with e.g. bypass diodes and careful supply bypassing.

Regards,

-H





Bruce Coward




From:   Bruce Coward <[email protected]>
To:     "[email protected]" <[email protected]>
Date:   05.10.2012 18:49
Subject:        [CANLIST] Protecting CAN Tcvrs
Sent by:        [email protected]




We have been using a mix of CAN Tcvrs for a while now and found them to be 
tolerant of quite a lot of abuse on the CAN lines. We normally take CAN-H 
and CAN-L straight to the CAN socket without any filtering or spike 
protection and this has been ok over 5,000 product shipments.
 
However I am now running in an environment were a lot of hydraulic 
solenoids are being powered from the same vehicle battery and on a 15 node 
net have already lost 5 CAN Tcvrs. I presume that this is either inductive 
or power supply linked high voltage spikes generated when the solenoid is 
de-powered. We are protecting the PSU with reverse diodes and a chunky 
Transzorb.
 
Can anybody recommend a suitable protection device or plan for the CAN 
interface that might prevent this problem reoccurring in the future?
 
Many thanks
 
Bruce Coward
Offshore Systems (UK) Ltd
T: +44(0)1425 610022  F: +44(0)1425 614794  SKYPE: OSUKL1
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