ISO1042: ISO1042 around RC parameter setting and calculate

Part Number: ISO1042

Hi Team,

My customer use this part now , but his loop2 T prop is 690ns and his RL is 150ohm / CL is 2.2nF.

And I suggest them to change to RL : 60ohm and CL : 100pF will run in right way. Right ?

But they still wonder to know how the spec only show the RL and CL need to use 60ohm and 100pF.

Is it come from any calculate result ? If so , could you please explain it  how to get this parameter  and share this tools for them.

They wonder calculate by themselves to find the suitable value. 

Eddie

  • HI Eddie,

    Thanks for reaching out.
    Your understanding is correct, if customer uses an RL of 60Ω and CL of 100pF, we expect them to see similar specs as listed in the datasheet provided customer also follows the rest of the conditions mentioned in datasheet under "test conditions" column which include CL(RXD) = 15pF or less and rise/fall time of TXD signal = 1ns or less.

    Most of the CAN networks use 120Ω termination for reliable communication and this 120Ω termination is used at the two far ends of a CAN network (see image below). Hence, the effective termination resistor seen by most CAN transceivers is going to be 60Ω. For this reason, most CAN transceivers will have their specifications defined around this value and so is the case with ISO1042 as well.

    For more information on CAN requirements, please refer to the below two application notes. Thanks.

    https://www.ti.com/lit/sloa101

    https://www.ti.com/lit/slla270



    Regards,
    Koteshwar Rao