K22 MAX input impedance?

[justinflor]

Is there a max input impedance on a GPIO pin for the MK22FX512AVLK12 in the "Pull up/down disabled" configuration?  I have  a circuit with a 100K series resistor that does not work using the K22 GPIO pin as an input.

[xiangjun_rong]

Hi, Justin,

Pls refer to section 5.2.3 Voltage and current operating behaviors in data sheet of K22.

The Input leakage current (per pin) in full temperature range is 1uA, which means that the input impedance is 1M ohm. For the GPIO input function, the 100K ohm is too large, which leads to the fact that you can not read the GPIO pin logic correctly. I think you can read correct logic if the external serial resistor is less than 20K ohm from my experience.

Hope it can help you

BR

XiangJun Rong