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TCAN1043H-Q1: TCAN1043HDRQ1 EN and STB VIH threshold

Pengpeng Li
Prodigy 30 points
Part Number: TCAN1043H-Q1

Tool/software:

Hi TI support team，

I checked the VIH for EN and STB is 0.7Vio, If the Vio is 5V,so the min Vih is 3.5V and max Vil is 1.5V. If the voltage is between 1.5 and 3.5, such as 3.3V. what's the status for EN and STB pins? Whether the CAN communication would be normal?

  • 0
    Prodigy 30 points

    Actually we met an issue with this CAN ASIC. We are using TC399 as the MCU and two GPIO ports in the MCU connecting with CAN_EN and CAN_STB are power supplied with 3.3V. So the maximum VOH for the two GPIO ports in the MCU will be 3.3V. When we configured the default low for the two ports, there will be no communication, we thought it would be reasonable since the 3.3V is below the CAN VIH threshold with 3.5V. But when we configured the default high for the two ports, the CAN communication can still be built and it's normal. So we are wondering for the different behavior. Could you please help to check and share your idea. And even though the CAN communication is normal with the default high configuration, we still consider there exist some risk and we would update the circuit to give 5V power supply for the two GPIO ports so that it could generate VOH with 5V to CAN_EN and CAN_STB. Please help to check and correct me if it's wrong and feel free to contact me if anything unclear. 

    And do you have the LTspice model for this ASIC-TCAN1043HDRQ1, I would like to conduct simulation with 3.3V and 5V input for CAN_EN and CAN_STB pins to see the behavior. If you already had the data, kindly help to share it to me. Thanks. 

  • 0 in reply to Pengpeng Li
    TI__Genius 13492 points

    Hi Pengpeng,

    Thanks for reaching out on E2E.

    Unfortunately, we cannot guarantee any behavior in between the 0.7*VIO and 0.3*VIO range as we do not validate or test for this. Please match the MCU and VIO voltage reference for the best results. If your MCU outputs a maximum of 3.3V, then the VIO reference pin on TCAN1043H should also be tied to 3.3V. Referencing both MCU and TCAN1043H VIO pin to 5V will also work.

    As for modeling, TCAN1043H only has an IBIS model available: https://www.ti.com/lit/zip/sllm394 

    Best,

    Ethan