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TCAN1043A-Q1: INH do not output when VSUP rise from 4.1V

Devin Hu
Prodigy 80 points
Part Number: TCAN1043A-Q1

Tool/software:

Hi TI experts

When I shut off the Vsup from 12V,the voltage fall to 4.12V,INH do not output,and then turn the power on,Vsup rise to 12V,but INH do not pull to high.Is it normal?

We use INH to enable PMIC IC with wake pin,and PMIC will be turn off if wake pin below 5V(INH in here)

  • 0
    TI__Genius 13842 points

    Hi Devin,

    I am reviewing your post, and I will get a response to you by EOD tomorrow. 

    Thanks for your patience,

    -Ethan

  • 0
    TI__Genius 13842 points

    Hi Devin,

    Thanks for reaching out.

    Based on the current description, the device is entering a protected mode since it is below UVSUP. Please refer to UVSUP in the Power Supply Characteristics section and Section 8.3.8.4 of the datasheet for details on UVLO.

    Once VSUP returns above UVSUP rising (~4.4V), the device is in Sleep mode.

    Let me know if that answers your question.

    Best,

    Ethan

  • 0 in reply to Ethan Sempsrott
    Prodigy 80 points

    Hi Ethan

    According 8.3.8.4,The Transceiver will be in CAN off state,but I didn`t find ICC characteristic in Datasheet when IC in CAN OFF state,The ICC will be under 5uA in off state? I think it will be lower than ICC in sleep mode.

    If an undervoltage event occurs on VCC and VIO,the transceiver will enter to sleep mode,but an undervoltage event didn`t occur on VSUP at the same time(maybe more than 4.4V),and  then  pulled to VSUP 12V,the transceiver will still in sleep mode.

    Some times  an undervoltage event occur on VSUP(less than UVvsup),the transceiver wiil in to normal mode after pulled VSUP to 12V.

    The key condition of transceiver`s  state after VSUP pulled to 12V is wether the VSUOP undervoltage occured.It may be in different state.

  • 0 in reply to Devin Hu
    TI__Genius 13842 points

    Hi Devin,

    When TCAN1043A is inside the UVSUP(falling) and UVSUP(rising) range which is from 3.5V to 4.4V, the device is in a protected mode. In protected mode, the device functionality is disabled and high impedance. Table 8-4 shows this. ICC in protected mode is not mentioned in datasheet, but it will be less than 5uA. 

    The mode that TCAN1043A returns to after an undervoltage events depends on how low the voltage went. If VSUP drops into UVSUP range from 3.5V to 4.4V, the device will be in Sleep mode once VSUP is returned to a proper voltage (>4.5V). 

    However, if the voltage drops below UVSUP range, which is less than 3.5V, then the device will reboot and enter the "Power on" sequence. This is effectively a cold start, and the device will enter into Standby mode and likely Normal mode after VSUP is above 4.5V. 

    Regards,

    Ethan

  • 0 in reply to Ethan Sempsrott
    TI__Intellectual 1718 points

    Hello Ethan, 

    If my understanding is correct, INH can not get back to high even with Vsup rising back after cold-crank of 4.1V because of pretected mode. This is not the expected behavior of my customer, and they're looking for other TI CAN device without protected mode. Unfortunately, my customer found that competitor has such device, but we don't. Right? Do we have device without protected mode? Please advise. Thank you.

  • 0 in reply to Kenneth Lee
    TI__Genius 13842 points

    Hi Kenneth,

    INH can go back to high after VSUP drops into the UVSUP range. It just needs the right configuration to help it switch modes.

    INH is related to the mode that TCAN1043A is in. If VSUP drops into the the UVSUP range (but not below this range), then after returning to a valid VSUP voltage then device will be in Sleep mode (which has INH low). Please reference Figure 8-4 in the datasheet. TCAN1043A can be woken up using a variety of methods which will restore INH to high (particularly Standby, Normal, and Silent mode). 

    This protection mode is a feature that keeps the bus and logic lines high impedance when there is an abnormality with VSUP. This prevents any damage from taking place when the voltage levels are unknown.

    If you have any further questions, please create a new E2E thread so we can keep the questions organized.

    Thanks,

    Ethan

  • 0 in reply to Ethan Sempsrott
    TI__Intellectual 1718 points

    Hello Ethan,

    Thank you for your help. I think I need to share customer block diagram via email to discuss further.