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Questions on the ADM3053 and CAN Bus Isolation

Question asked by dbesson on May 10, 2012
Latest reply on May 13, 2012 by hmarais

I am currently using a standard CAN Bus connections using non-isolated transceivers in my controls. But recently we encountered what I think could be ground loop problems. We are experiencing occasional crashes of the bus and even the total destruction of some of the transceivers. So now I need to isolate the whole network and I found the ADM3053 which sounds very interesting.

 

I bought a few samples and I'm testing them , but now I have some questions which are not so clear in the datasheet.

 

The Rs pin: Its said that it must be tied to "ground" for fast operation, or through a resistor for slope control. It's not specified which ground to use, but if I look at the block diagram, I assume it should be tied to GND2? (The bus side of the chip). I used GND2 in my tests and it works, but I don't want to break the isolation by using the wrong ground!

 

Also I couldn't find in the datasheet if that pin can be used for "listen only" mode. I know the transceiver I'm using right now turns off the transmitter if I apply 5V to the Rs pin or if I leave it floating (the output transistors never switch on because there is no current flowing out of Rs pin to ground). If I still want to use that method of controlling the Rs pin to disable the transmitter, do I need to use an extra opto on that pin? Or is there a way to set the transceiver in receive only mode through the logic side? I don't want to turn off the whole transceiver, just the transmitter.

 

One more question, Since the ADM3053 is completely isolating the control logic and power supplies from the CAN Bus, is it wise to use some extra TVS (Transient Voltages Suppressors) on the bus side even if I have TVS protection on the logic side power supply?

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