Re: CAN Bus protection (100VDC)

StanV wrote:
We designed a machine where we have at some place the CAN-bus signals
and HighVoltage power (100VDC and 220VAC) on the same cable.

So , we are just awaiting a faulty cable or connector to get these
voltages on the bus.

Opto-isoloating every nodes seems to be complex. I also found some new
maxim CAN-driver that is protected upto 80VDC. Unfortunatly we are
unable to change the CAN drivers inside the nodes.

I also found a few other components for protecting a CAN bus , but they
are mostly intended for voltages upto 24V.

In what direction could i look for protection components, or maybe it
is just to difficult to protect the bus for such levels ?

Any pointers very welcome.

Stan.

If you are making the CAN signals 'ride' on the power, then they will
have a **common mode voltage** of whatever that power is, and you'll be
hard pressed to find an IC with 311V of common mode range (the peak
voltage of 220Vac) and can withstand a similar negative excursion.
It's not just protection, it's data recovery in the presence of such
high common mode voltages that will be the problem.

CAN has a nominal common mode voltage of 2.5V relative to circuit
common (CAN High has excursions above this, CAN Low goes below this by
about a volt or less). You might get a floating circuit, or perhaps
even capacitively couple the signal and then shape it back up again,
but I would see this as a design effort in amplifiers, not simply
plopping down ICs.

Cheers

PeteS

.

Relevant Pages

  • Re: CAN Bus protection (100VDC)
    ... we are just awaiting a faulty cable or connector to get these ... voltages on the bus. ... are mostly intended for voltages upto 24V. ... You have a couple of protection issues. ...
    (comp.arch.embedded)
  • Re: CAN Bus protection (100VDC)
    ... If you are making the CAN signals 'ride' on the power, ... It's not just protection, it's data recovery in the presence of such ... high common mode voltages that will be the problem. ...
    (comp.arch.embedded)