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TPS65313-Q1: Watchdog function

Part Number: TPS65313-Q1

Hi Experts,

What's the initial state of the Watchdog function in TPS65313-Q1? Customer want to disable the watchdog from initial power on, how to achieve it? Thanks.

  • Hi,

    Watchdog function cannot be disabled. When the PMIC powers up, it enters diagnostic state and in this state, watchdog needs to be configured and serviced. If watchdog is not configured and not serviced in diag state, diag state time out happens (640ms typ) and device enters safe state after watchdog error counter overflows. However, in safe state all the regulators are active and NRES is high.

    How to go to active state from safe state: If device is in safe state due to watchdog time out, watchdog needs to be serviced and once error counter reaches 0, safe to diag command needs to be given and this brings the device to diag state. Once you are in diag state, diag exit command should be given to go to active state.

    please refer to the device datasheet for more details about watchdog implementation.

    Regards,

    Murthy

  • Hi Krishnamurthy,

    Thank you so much for your detailed reply. In customer's design, TPS65313 is used to power MCU, but in their preliminary debug stage, the MCU software is not ready to service the watchdog of TPS65313.  Based on your reply, TPS65313 will enter diag state and then enter safe state in this condition. So customer can only debug the device in safe state, right? But actually customer want TPS65313 work in normal mode. Will all monitoring and protection functions stay enabled in safe state? Thank you.

  • Hi,

    Yes. your understanding is correct and if device is not configured initially during the power up, device will land in safe state and they have to continue to work in safe state. Even in safe state, device has most of protection features and it should be OK to work in safe state. But in safe state, ENDRV signal cannot go high and if they are using this feature, they have no other option, but to go to Active state after serving the watchdog. Please refer to datasheet "Device Fail-Safe Controller State Diagram" to understand more about global reset conditions and device  operation. Can you please let me know more details about this project / opportunity? You can send me email if you dont want to disclose this on E2E.

    Regards,

    Murthy