TPS3813K33-EP: WDI vs Reset

I forgot to say:

Channel 1 (yellow) is reset pin and channel 2 (Blue) is WDI pin.

Regards,

Damien

Hey Damien,

Would you be able to provide me with a schematic?

I am unsure of what the issue is at this time and need to investigate further.

Thanks,

Daniel

Hi Daniel,

Here is the schematic for the watchdog. WDG is coming from a MCU GPIO.

**Schematic deleted to protect IP - 05/01/20**

The scope shown in my previous mail is reset from U7 pin 6 and WDG.

About the schematic, TP6&TP7 are used in production to download FW in the MCU. When they are connected togetther, that isolates the reset from the watchdog to the MCU and FW download is possible through JTAG probe.

Regards,

Damien

Note also I added a pull up resistor to pin 6 of U4 (doesn't appear in the schematic)

Regards,

Damien

Hey Damien,

Is this an issue you have seen on multiple devices or just this one device?

Thanks,

Daniel

Hey Damien,

I just noticed that the schematic you sent shows the RESET as not inverted while it is inverted on our datasheet (a NOT RESET).

Can you try inverting the reset signal in your test?

Thanks,

Daniel

Daniel,

See my answers.

"Is this an issue you have seen on multiple devices or just this one device?"

I have only one board.

I don't understand your point:

"I just noticed that the schematic you sent shows the RESET as not inverted while it is inverted on our datasheet (a NOT RESET).

Can you try inverting the reset signal in your test?"

What do you mean?

The traces I put in my first question was from a scope with probes connected on a board. It is not a simulation.

what is the link with my issue?

Thanks

Regards,

Damien

Hey Damien,

Apologies I was confused on that last question.

Why do you keep WDI high after the second pulse?

There are sometimes issues with triggering a pulse before the window has come back up.

You may want try pulsing instead of holding high.

Hey Damien,

Was this able to solve your issue?

Thanks,

Daniel

Hi Daniel,

The datasheet is not clear. In our case (WDT=3.3V and WDR=GND), What are the pulse duration needed?

Can you give me an example of values?

What are the min and max pulse duration and what is the min max pulsing ?

What are the min, max and typ boundary time, the datasheet doesn't mention any values for our our configuration (only when capacitor is connected to WDT?

Thanks

Regards,

Damien

Hey Damien,

The lower window frame has values right next to the values for the regular window frame in the datasheet.

Thanks,

Daniel