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TPS65381A-Q1: TPS65381 applications question check

Sulyn ZHANG
Expert 8700 points
Part Number: TPS65381A-Q1

Hi team,

My customer is using TPS65381 with our TMS570, several questions want to quick check with you urgently, would you pls help look into these questions, thanks a lot!

1. How to use NRES pin usually and what's trigger condition?

2. How to use the WDI effectively for typical application?

3. How to use and trigger ENDRV station? For example, how to avoid trigger ENDRV when programming TPS65381?

Best regards,

Sulyn Zhang

  • 0
    TI__Mastermind 20590 points

    Hello Sulyn,

    I would suggest studying the TPS65381A-Q1 datasheet and safety manual.  They have the details you are looking for to these questions.  Due to the highly complex nature of functional safety and the safety mechanisms those documents have much more detail than we can summarize on the E2E forum.  The Chinese translated datasheet may be found at:  http://www.ti.com.cn/product/cn/TPS65381A-Q1/description

    A1:  NRES is the reset output pin for the TPS65381A-Q1.  The conditions to cause it to go low (reset the MCU) is best summarized in Figure 5-14 shows the reset and enable circuit.  Also Figure 5-16. Device Controller State Diagram will helpful to understand the state transitions on the TPS65381A-Q1 that impact NRES.

    A2: The watchdog has two modes: Q&A mode using the SPI where the TPS65381A-Q1 ask the MCU a "question" and the MCU must answer.  That is normally the mode used with the TMS570 and offers higher diagnostic coverage than the Trigger Mode (OPEN/CLOSE window watchdog) where a trigger pulse must be sent from the MCU to the TPS at the appropriate OPEN window.  Both modes are configurable in timing.  Section 5.4.10 Watchdog Timer (WD) provides all the details.

    A3:  ENDRV is the safing output.   The conditions to cause it to go low is best summarized in Figure 5-14 shows the reset and enable circuit.  Also Figure 5-16. Device Controller State Diagram will helpful to understand the state transitions on the TPS65381A-Q1 that impact ENDRV.  It will be low when the MCU is programmed assuming the MCU is "empty" when the programming starts.  It cannot output a HIGH (or enabled) level if the MCU is not sending good events to the TPS65381A-Q1 watchdog.  While WD_FAIL_CNT > 4 it will be low no matter the other conditions.  If the MCU is un-programmed or being programmed and not providing good events to the TPS the WD_FAIL_CNT will increment and ENDRV will be low.  Also clearing ENABLE_DRV bit to 0 (default is cleared) will immediately cause it to go low.

    Best Regards,

    Scott