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TCAN1145-Q1: Sleep mode current : selective wake enabled

Shinji Tsuji
Genius 14139 points
Part Number: TCAN1145-Q1

Hi team,

Could you advise the sleep current at selevtive wake enabled?

"Additional current when selective wave is enabled and bus active" seems large. 

I would like to know the current at the state described in the bottom right picture below. 

regards,

  • 0
    TI__Guru 53555 points

    Hi Shinji,

    When TCAN1145 is in Sleep mode with an idle bus, the device turns off the bus bias and the internal oscillator. In this state, only the Isup Sleep current is drawn from the power supply, regardless of partial networking configuration. Only once the device recognizes a WUP will the the partial networking receiver be activated and start to draw the extra current specified on the datasheet. Note that this mode is only entered when a non-PN transceiver would wake fully into Standby mode. 

    Once the bus return to an idle state (tSILENCE after the last bus activity), the transceiver will return to the low power state with the internal oscillator switched off. 

    Let me know if this is clear and if you have any more questions.

    Regards, 
    Eric Schott 

  • 0 in reply to Eric Schott1
    TI__Genius 14139 points

    Hi Eric-san,

    "Note that this mode is only entered when a non-PN transceiver would wake fully into Standby mode. "

    I don't understand this sentense. What does non-PN transceiver means in this context? Is that TCAN1145 in PN configuration or other non-PN device

    connected on the bus?

  • 0 in reply to Shinji Tsuji
    TI__Guru 53555 points

    Hi Shinji, 

    Sorry for the confusion. 

    I am referencing the standard behavior of a CAN transceiver waking up to a wake up pattern (WUP). Other transceivers that don't support partial networking such as the TCAN1043A will wake from Sleep mode if it detects this WUP on the bus, which is satisfied by any CAN activity. If TCAN1145 is not configured to use partial networking (SW_EN = 0), then it will also behave in this way and wake from Sleep on any CAN activity. If partial networking is enabled (SW_EN = 1), then this bus activity will not result in a transition to Standby. Instead, this will cause the internal PN receiver to become active (drawing a bit more current than "deep Sleep" mode) so that it can monitor the CAN bus for a WUF. Only once this WUF is recognized by the transceiver (or some other wake event occurs) will the device leave Sleep mode and drive INH high. If the correct WUF is never identified and the CAN bus returns to an idle state (~1 second of no activity), this PN receiver will turn off and the device will go back its lowest power Sleep state. 

    I hope this is more clear. Let me know if there's anything I can clarify further. 

    Regards,
    Eric Schott

  • 0 in reply to Eric Schott1
    TI__Genius 14139 points

    Hi Eric-san,

    Thank you. Let me clarify one condition below. 

    When one CAN PN PHY on the bust wakes up by WUP and WUF and starts communication while the other CAN PN PHY 

    doesn't receive dedicated WUF, then that PN PHY returns to deep sleep mode while the other PHY on the bus dominates and actively using the bust?

    I would like to know what the "Additional current when selective wave is enabled and bus active" value means. 

    Does it means that the device is not fully wake up, but PN receiver consumes this current?

     

    If selective wake feature is enabled, how much is the total current drawn by IC in following cases?

    #condition 1. Deep sleep. bus idle. 

    #condition 2. Recieve WUP and PN receiver enabled. But doesn't receive WUF.  

    #condition 3. Receive WUP, but no WUF received and returned to sleep mode. 

    #condition 4. Fully wake up. *This should be same as normal mode. 

    regards,

  • +1 in reply to Shinji Tsuji
    TI__Guru 53555 points

    Hi Tsuji-san,

    The 400µA of additional current is only needed when the CAN bus is active. This is when any CAN frame has appeared on the bus within the last second. Once the CAN bus is silent (no CAN frame for > 1 sec), then this additional current will no longer be consumed. 

    All estimates below use maximum values from the datasheet. 

    Shinji Tsuji said:
    #condition 1. Deep sleep. bus idle. 

    37µA
    35µA from lp WUP receiver and other quiescent currents + 2µA from wake pin (dependant on WAKE circuit).

    Shinji Tsuji said:
    #condition 2. Recieve WUP and PN receiver enabled. But doesn't receive WUF.  

    587µA - 627µA* 
    550µA from PN receiver, 40µA from active bus bias*, 35µA from other quiescent currents + 2µA from wake pin.

    *active bus bias is only active for tWK_TIMEOUT (~2ms) after a bus state transition. After this time, the bias will move back to an inactive state and the 40µA current will not be needed. The 550µA PN receiver will be disabled ~1second after the last CAN activity.

    Shinji Tsuji said:
    #condition 3. Receive WUP, but no WUF received and returned to sleep mode. 

    37µA
    35µA from lp WUP receiver and other quiescent currents + 2µA from wake pin.

    Shinji Tsuji said:
    #condition 4. Fully wake up. *This should be same as normal mode. 

    1.5mA
    Normal mode.

    Regards, 
    Eric Schott 

  • 0 in reply to Eric Schott1
    TI__Genius 14139 points

    Hi Eric-san,

    Thak you very much!

    regards,