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ISO1042: Protection of CAN bus from high voltage 70V

HARI T O1
Expert 1275 points
Part Number: ISO1042
Other Parts Discussed in Thread: ESD762

Dear Team,

I am using ISO1042 in my design. My can voltage can go upto 70V.

I checked the reference design the ESD(CDSOT23-SM712) diode  reverse standoff is  12V (Max).

I am not able to see an ESD diode with standoff of 70V.

May I know is there any other method to protect the CAN bus from high voltage.

Regards

HARI

  • 0
    TI__Expert 8030 points

    Hi Hari,

    Thanks for reaching out.

    HARI T O1 said:
    May I know is there any other method to protect the CAN bus from high voltage.

    The ISO1042 supports of a common mode voltage range of +/- 30V and has a built-in fault protection feature of +/- 70 V for transient voltages. If your application requires additional protection against high voltage ESD and transients, then I recommend that you achieve this additional protection by connecting TVS or ESD diodes to the CAN bus. 

    HARI T O1 said:
    I am not able to see an ESD diode with standoff of 70V.

    Any TVS or ESD diode that you select to protect the CAN bus of the ISO1042 needs to have clamp voltage that is under 70 V (this the maximum voltage that the built-in fault protection feature of the device can support). Otherwise, the ISO1042 may be damaged during an ESD or transient voltage event. Additionally, it is also recommended to use a TVS or ESD diode that has a breakdown voltage just outside of the CAN bus common mode voltage range of the ISO1042. Following this guideline will help ensure that diode will only conduct whenever an ESD or transient voltage causes the CAN bus voltage to exceed to common mode range supported by the device. 

    The CDSOT23-SM712 can be used to protect the CAN bus of this device if the application does not require the full common mode range of the device to be supported (+/- 30 V). If you want to be able to support the full common mode voltage range of the device, you can select a TVS or ESD diode that has a greater VBR value and a max clamping voltage that is under 70 V, such as the ESD762 or the ESDCAN05-2BWY. 

    Regards,

    Kenneth