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TPS3850-Q1: About WDI pulse width of TPS3850-Q1

Part Number: TPS3850-Q1

I want to confirm the minimum pulse width and maximum pulse width of the WDI signal.

It is described on page 6 of TPS3850-Q1 datasheet as follows.
Minimum WDI pulse duration : 50ns(Typ)

Q1.
Does this mean the minimum pulse width of WDI?

Q2.
If Q1 is yes, Does this applicable to both Hi→Lo and Lo→Hi?

Q3.
The maximum pulse width is not specified.
Is this understanding correct?

-Harukawa

  • Harukawa,

    A1. Yes, minimum pulse duration required on WDI is 50ns.

    A2. No, This is required for falling transitions (Hi to Lo). Rising transitions are not detected. So each falling transition must be 50ns minimum before the next falling edge.

    A3. The maximum pulse width is the same as t_WDU (Widow Watchdog upper boundary) because the falling edge of the hi to lo transition must occur before this value. t_WDU is configured by CWD, SET0 and SET1. Please refer to table 6.6 Timing Requirements.

    Please let me know if you have any other questions! Thanks.

    -Michael

  • Michael-san,

    Thank you for your response.

    Please refer to the attached file to confirm my understanding.

    Is my understanding correct about minimum WDI pulse width and maximum WDI pulse width?

    -Harukawa

    TPS3850-Q1_WDI pulse width.xlsx

  • Harukawa,

    Correct except for the FALLING EDGE TRANSITION on WDI must occur before tWDU. In your attachment, it looks like FALLING EDGE TRANSITION occurs at same time as tWDU. Falling edge must occur before tWDU. Everything else is correct.

    -Michael