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TCAN1145-Q1: Wake Pin setting and UV behaviour

Nikhil Jotwani
Prodigy 740 points
Part Number: TCAN1145-Q1

Hi Team, 

For the TCAN1145-Q1, I have a couple of questions.

1. Can the wake pin for the TCAN1145-Q1 be connected to ground? 

2.  Under voltage :

    1.  For the device, there are three power sources, 12V Battery, 5V and 3.3V
    2. The requirement is that the CAN communication should work at battery voltage 6V. Considering various tolerances and drops, the voltage at the VBAT pin would be 5.4V 
    3. The CAN VCC is supplied from the 5V DCDC converter, which has its own tolerances and can drop down to 4.7V. In this case, the CAN device will be in under voltage condition, which will set a UV flag.
    4. When the UV is detected, can all the CAN information be read via SPI? This information is needed to know the state of the device (UV or not UV) and when exactly the device comes out of the UV condition and CAN messages can be sent again. Can you kindly advice on this state of the device.
  • 0
    TI__Guru 74252 points

    Nikhil,

    Thanks for bringing this to E2E.

    1. Yes, it can. If the local WAKE function is not being used, we typically recommend connecting this pin to either battery or ground. Battery actually consumes 1-2uA less current, but either one is fine.

    2. If failsafe mode is disabled, if UVCC occurs, a tUVSLP timer will start. Once this elapses, the device will go into sleep mode, where SPI is available if VIO is present. At this point the registers can be read. If failsafe mode is enabled, the same sequence of events will happen, except the device will go into failsafe mode rather than sleep mode, and again SPI will be available if VIO is present. So either way, SPI can be read once the tUVSLP timer elapses.

    Please let me know if there are any other questions.

    Regards,

    Eric Hackett