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TPS3828: WDI in Hi-Z and /RESET pin status

Part Number: TPS3828
Other Parts Discussed in Thread: TPS3823, TPS3820, TPS3824

Dear Team,

To develop our new project, we are going to apply your TPS3828 to our desing.

Before we apply it, we have a couple of some questions.

[Question 1] - If WDI pin is in Hi-Z, then what's status of /Reset pin with pull-up resistor though VCC ?

When we connect JTAG to our board, All GPIO of MCU is going to be status in Hi-Z.

So, MCU is going to not send clock to TPS3828 and WDI pin will be in Hi-Z.

At this time, /RESET pin does not assert as the below? 

[Page 11 on TPS3828 datasheet]

"If the WDI pin detects that it is in a high-impedance state, the TPS3820, TPS3823, TPS3824, or TPS3828 will generate its own WDI pulse to
ensure that RESET does not assert."

[Question 2] - What's VCC range of /Reset pin with pull-up resistor?

We want to connect power supply(12V) to this pull-up resistor.

Is OK or not?

If it's not, please let me know range from min. Voltage to Max. Voltage?

  • Hello,

    Answer 1: When WDI is in high-Z, /RESET will be inactive and logic high because the device detects WDI is in high impedance state and generates its own WDI pulse internal to the device which prevent /RESET from activating to logic low.

    Answer 2: The ABS MAX ratings in table 7.1 states /RESET and RESET should not exceed VDD + 0.3V and must not be below -0.3V The absolute max current at the output when Voutput > VDD is +/- 10mA. 

    I hope this answers your questions. Please let me know if you have any additional questions. Thanks