Unused pin management

AN2871

22/25

Doc ID 15304 Rev 3

5

Unused pin management

In some applications, not all pins of the device may be needed.

For all unused pins (digital pin and analog pin), it is recommended that software configure

them as floating input with internal or external weak pull-up/pull-down. Using both internal

and external weak pull, pay attention to use the same pull type so to avoid direct link to

VDD/VSS. For unused analog pin don’t enable the analog pad control PCR[APC].

More pins can be linked to the same pull-up/down resistance.

Additional recommendation:

All unused pins should be tied off. Software doesn't enable the output buffers of the pads

(PCR[OBE] bit) to avoid a path with current injection inside the device.

There is no specific recommendation for external resistances but it is good practice to use

10 kOhm as pull-up/down resistance.