topic TJA1101 WAKE_IN_OUT pin in S32K

TJA1101 WAKE_IN_OUT pin

YeseulLee — Mon, 20 Jan 2025 08:34:23 GMT

Hello,

I'm trying to validate a local wake up by applying a pulse to the wake_in_out pin.

Looking at the datasheet, I don't know how to see the minimum voltage at which the wake_in_out pin operates.

What is VIH,th (Minimum Voltage Perceived as High)?

The datasheet says that VIH,th is 2.4V, but VIL,th is 3.75V.

So what happens when I apply 3.3V to wake_in_out pin?

Re: TJA1101 WAKE_IN_OUT pin

PavelL — Mon, 20 Jan 2025 13:32:31 GMT

Hello @YeseulLee ,

to validate WAKE_IN_OUT as input pin, you should apply voltage below VILmin (2.4V) and above VIHmax (4.1V). Please notice that only a rising edge will trigger a local wake-up.

Overlapping of VIL and VIH might look like a bug in the datasheet or in design, but it is correct - there is defined hysteresis min 0.25V and max 0.8V, which guarantees correct function.

If you apply 3.3V (assuming jump from 0V & CONFIG_WAKE=0), the WAKE_IN_OUT pin might or might not trigger the wake-up event because you are in the middle of guaranteed VIH threshold 2.8V - 4.1V.

Best regards,

Pavel

Re: TJA1101 WAKE_IN_OUT pin

YeseulLee — Tue, 21 Jan 2025 00:51:47 GMT

Thank you for answer, Pavel