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TCAN1043G-Q1: TCAN1043G-Q1 voltage question

Alex Lai70
Prodigy 215 points
Part Number: TCAN1043G-Q1
Other Parts Discussed in Thread: TCAN1043

Hi

For TCAN1043G, we checked the impedance is 60 ohm on the BUS.

But we found the voltage between CANH and CANL is around  10V.

Is it normal? what should be the right voltage between CANH and CANL?

  • 0
    TI__Guru 62910 points

    Hi Alex,

    Do you mean that you are using TCAN1043 and in your system you are measuring a 10-V difference between CANH and CANL?  That would not be expected.

    The CAN output has two states when in normal mode - recessive and dominant.  When TXD is high (at VCC), the output is recessive and the CANH/CANL pins are weakly biased to VCC/2.  In this state there should be no significant difference between CANH and CANL.  When TXD is low (at GND), the output is dominant and CANH is pulled up towards VCC while CANL is pulled down towards GND.  This creates a differential voltage that at most could equal the VCC voltage but is generally lower (e.g., ~2-3 V, due to voltage drop through the driver source impedance).

    If you are seeing 10 V, then, something must be wrong in the set-up.  Can you please let us know more about how the device is being used?  If you could provide a schematic showing the TCAN1043 implementation as well as the measured voltages at each pin when this occurs I think it may help.

    Regards,
    Max

  • 0 in reply to Max Robertson
    Prodigy 215 points

    Hi.

    we had resolved our question.

    thanks.