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TPS65381-Q1 Watchdog and Over Temperature Protection Question

KevinZhang123
Expert 5740 points
Other Parts Discussed in Thread: TPS65381-Q1

Hi, Team

A Car-OEM customer GAC is evaluating TPS65381-Q1 for their EPB system. They have questions on it.

1. There are two modes of watchdog in TPS65381-Q1: Trigger Mode or Question and Answer Mode.

Customer need to turn off all the watchdog, when they program the software code to MCU. Because there is no software in MCU before program, and MCU can not feed the watchdog.

Can the watchdog in TPS65381-Q1 be turned off without MCU control through SPI? How can we do it?

2. When there is over temperature condition, bit 0~2 of SAFETY_STAT_1 Register will be 1. When over temperature condition remove, the bit return to 0.

over temperature condition occur --> power output disable and related register bits set to 1 --> MCU power down (MCU can not read out the over temperature condition) --> when over temperature condition remove --> MCU power up but the related register bits return to 0

How can MCU log the over temprature condition?

Thanks

Kevin

  • 0
    TI__Mastermind 30260 points
    Kevin,

    The appropriate applications engineer has been notified of your post and will respond accordingly.

    Regards,
    Brian
  • 0
    TI__Mastermind 20580 points

    Hi Kevin,

    A1:  The watchdog is always running, however in default state after initialization WD_RST_EN = 0, so there is no RESET from the watchdog, the fail counter will simply increment to 7 and remain there with no impact to the device from the watchdog.  If the MCU is blank (not flashed) and TPS65381 is powered up, the device will go to DIAGNOSTIC state for ~ 512ms, then DIAGNOSTIC state time-out  will occur causing a transition to SAFE state.  Since the MCU will not have configured any other registers since it is not flashed (programmed) the TPS65381 will stay in SAFE state until re-started by the OEM programming system or the MCU once it is programmed.  In SAFE state the VDD6, VDD5, VDD3/5 and VDD1 (external FET LDO controller) will be ON.

    A2:  If the system requires storing of an OT even, some OT events do not cause the TPS65381 to change state or go through RESET and the MCU could log those directly.  For the other ones, it is not directly possible to read them out during the OT event and they will be re-initialized after the thermal event is gone and the device re-starts.  An external temp sensor tracking the ECU temp would be needed.  Some next generation devices will store this for MCU reading after RESET, however the TPS65381 generation does not. 

    Scott

  • 0 in reply to Scott Monroe
    TI__Mastermind 20580 points
    Hi Kevin,

    Since I never heard back I assume this answered your questions so I'll close this post. If you have additional questions please submit a new post or if it is on this topic you can add to this thread and we can re-open the post.

    Scott