S32K3 GPIO Source Current

[FabianGeiger]

Hi,

I want to use S32K3 in a Sensor Application to power some sensors and external circuitry directly from GPIOs. In the Datasheet, there are specifications, where a minimum GPIO current is given (S32K3xx Data Sheet, Rev. 10, 07/2024 Table 24, 3.3V or Table 25, 5V).

Though I do not completely understand these specs.

IOH_50_S is 1.6mA,min for VOH >= VDD_HV_A/B - 0.7V as example from Table 25.

Does that mean, that I can only draw 1.6mA from an Standard GPIO running at 5V?
From the given measurement condition, can I also assume, that the Resistance of the GPIO-Structure is somewhere around 450Ohm (0.7V/1.6mA)?

Thank you!

[danielmartynek]

Hi Fabian,

The specification means that NXP can guarantee that the voltage will not drop by more than 0.7V at 1.6mA source current.

If the source current is higher, the voltage can drop further.

The I–V characteristic is not exactly linear but exponential (especially at higher currents).

Refer to this AN: Input/Output (I/O) Pin Drivers on HCS12 Family MCUs

https://www.nxp.com/docs/en/application-note/AN2434.pdf

It is an older AN, but the principles remain the same.

There are also IBIS models available in the S32K3xx HW package.

https://www.nxp.com/webapp/Download?colCode=S32K3_HW-DesignPackage

Regards,

Daniel