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About ISO1050

makoto fujimoto
Prodigy 190 points
Other Parts Discussed in Thread: ISO1050

We are useing ISO1050(Isolated CAN Transceiver) on our developping prroduct right now.

The ISO1050 datasheet says below.
・Voltage at any bus terminal (CANH, CANL) –27to40 V
　*Differential bus-side voltages are　measured to the respective bus-side GND2 ground terminal.

I have a question about that.

When we use ISO1050 under the below condition,does it cause  permanent damage to the device?

(1)GND2 pin：Open（No connection)、CANH pin : Input 38V voltage、CANL pin : Input 0V voltage
(2)GND2 pin：Open（No connection)、CANL pin : Input 38V voltage、CANH pin : Input 0V voltage


We are developping products according to NMEA2000 Standard.

NMEA 2000 :STANDARD FOR SERIAL-DATA NETWORKING OF MARINE ELECTRONIC DEVICES
           It is based on CAN Standard.

NMEA2000 Standard says below,

2.4.6.1 No permanent damage shall result from a voltage level of +/-18.0 Volts applied
between any two wires in the interface for an indefinite period of time.


Best Regards

  • 0
    TI__Guru 55795 points
    Hi Makoto,

    ISO1050 should clearly be able to withstand 2.4.6.1 that you have described in your post i.e., ±18V between any CANH / CANL interface pins provided the potential at CANH & CANL with respect to GND2 is not exceeding the range -27V to 40V.
    Regarding the conditions (1) & (2), ISO1050 shouldn't damaged due to these test conditions as these are not violating -27V to 40V criteria.

    Regards,
    Koteshwar Rao
  • 0 in reply to Koteshwar Rao
    Prodigy 190 points

    Thank you for replying me.

    But,I still have some questions.


    ISO1050 datasheet says below.
    ・Voltage at any bus terminal (CANH, CANL) –27to40 V
    　*Differential bus-side voltages are　measured to the respective bus-side GND2 ground terminal.

    In thiscase, I think ,GND2 pin is connected to Network GND, and ISO1050 has reference GND.


    I'd like to know the case,ISO1050 has no reference GND.
    That is GND2 is open (no connected).


    Are there any troubles in ISO1050, when the GND2 is open and CANH is 38V and CANL is 0V ?
    Can I add some voltage(38V or 0V) to CANH or CANL pin withiout connetting GND2 to Network GND?


    It may occurs in NMEA2000's test condition.

    Regards,


    Makoto Fujimoto

  • 0 in reply to makoto fujimoto
    TI__Guru 55795 points
    Fujimoto-san,

    Ideally if GND2 is open and not connected to the supply which is applying 38V onto the CANH/CANL bus, then it is as good as nothing is applied to CANH/CANL. But since one of the CAN lines is applied 38V and the other with 0V, this condition should not be worse than applying 38V at CAN line with respect to GND2 hence the device should withstand this test condition.

    Regards,
    Koteshwar Rao