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Original question:

TCAN1043A-Q1: Sleep mode

TCAN1043A-Q1: TCAN1043

Chetan Soni
Prodigy 80 points
Part Number: TCAN1043A-Q1

Tool/software:

We are doing the same 

nSTB =0

EN =1

INH comes down...(high impedance state)

We are using TPS6538 n with INH in high impedance state we send STBY cmd to PMIC ...While doing so INH or STB pin of TCAN starts toggling which does not ket PMIC to go sleep

Any suggestions?

  • 0
    TI__Guru 53555 points

    Hi Chentan,

    Thanks for sharing your question on E2E. 

    I'm not sure I understand the scenario here. I understand that the system is putting TCAN1043A into sleep mode by driving nSTB = 0 and EN = 1. This will cause the device to move it sleep mode after 50us and the INH signal will go into a high-impedance state. The INH signal will remain off until the transceiver receives some wake condition - WUP on CAN bus, toggle on WAKE pin, POR condition on Vsup, or a low-to-high transition on nSTB. 

    Because the nSTB signal is an input to the transceiver and not within the control of the device, I cannot comment on what might cause this pin to toggle. However, if this pin toggles with a frequency of 50us or longer, this toggling behavior would also occur on the INH output as the transceiver moves in and out of sleep mode based on the state of nSTB. 

    Let me know if my understanding here is wrong and if you have any idea what may be causing the nSTB pin of the transceiver to be toggling.

    Regards, 
    Eric Schott

  • 0 in reply to Eric Schott1
    Prodigy 80 points

    Thank you for detailed reponse. (I will elaborate the senario with Ocsiloscope capture soon)

    I am using the below circuit config - Need your review feedback on hardware perpective.

    - Can you please let me know how can i check POR on VSUP is not happening. the thresold values for POR and how it is going to impact INH pin.

  • 0 in reply to Chetan Soni
    TI__Mastermind 27590 points

    Hi Chetan,

    Sorry for your waiting. Eric is currently out of office, and we've seen other E2E thread regarding the same question here:

    https://e2e.ti.com/support/interface-group/interface/f/interface-forum/1363050/tcan1043a-q1-failing-mode-transition-through-stb-and-en-pin

    From the first picture of the waveforms you provided above, I'm not seeing POR on VSUP, but nSTB is not pulling LOW so the device doesn't enter the sleep mode, that's why INH is not turned off here.

    Your second picture shows nSTB is LOW while EN is High, so the transition to sleep mode is performed, INH also turned off as expected.

    As Eric said, we couldn't comment on what cause nSTB not going to LOW, this is an input pin from microcontroller and the transceiver is not able to control the digital input level.

    Since the application is using TI's MCU, I would recommend to contact the EP team (ASM-AUTO) for their helping to check your codes.

    Regards,

    Sean