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F28M35M52C: Unused GPIO and ADC pins

Part Number: F28M35M52C

After a redesign following pins are not used any more:

PH5_GPIO53    Pin 47

PH2_GPIO50    Pin 36

PH3_GPIO51    Pin 35

PJ1_GPIO57     Pin 62

ADC1INB0        Pin 117

ADC2INB0        Pin 136

For the above GPIOs the TRM is saying that default config is Z (Tri-State) so that is fine I guess. What about the ADC input pins? Any concern to leave them floating?

Best regards,


  • Frank,

    We suggest to ground any unused ADC inputs.  There's likely not much risk here to floating if this is a big effort to re-design the PCB, just trying to keep any potential noise away from the ADCs in general.

    I believe that the default state of the GPIOs is Input mode with a 4mA PU, so those should be fine to float if unused.