When do unused pins need to be left unconnected?
If there is no indication on the data sheet which meaning of NC applies, such pins should be left unconnected—or the manufacturer’s product engineers consulted for clarification. In general, unused inputs should not be left open circuit:
What to do with unused pins on a microcontroller?
In a typical microcontroller design, it’s normal to end up with some unused pins. These may be general purpose inputs and outputs or pins that are merely labeled as “NC” in the datasheet. The quick and easy solution is to leave these pins unconnected as this means less routing for the hardware as well as less space occupied on the PCB.
Which is the best software to terminate unused pins?
With comprehensive PCB design software like Altium Designer ®, terminating the unused pins with resistors is convenient. Altium’s offers all the necessary components and includes additional resources to help optimize your PCB design. If you have more concerns about unused pins, talk to an Altium expert for more tips.
When to connect unused pins to logic input?
If an unused logic input has internal pull-up or pull-down resistors/currents, it is not necessary to connect to the pin, but if the pin is likely to be exposed to electrostatic or RF fields, it may be sensible to do so by making an external connection to V DD or V SS, respectively 7.
What’s the best way to use unused IC pins?
Don’t use a capacitor; it would leave the pin floating, and the microcontroller doesn’t like the capacitive load in case it would become output. “Connect the pin to a supply source”. Same as above: if the pin should become output low you’ll have a short-circuit. “Leave unconnected, but make the pin output”. That’s the best solution.
Is it a good idea to leave an IC pin floating?
Leaving it floating is NOT a good idea. It may change level all the time, which may have undesired effects to the internally connected circuitry. You always want to have predictive behavior. If the input has an internal pull-up resistor this is a good solution, though, as long as you don’t forget to enable it.
What should you do with unused MSP430 pins?
Usually the datasheet will give you the optimal connection for unused pins, here is one for an MSP430: In production, you want to test all pins to check for defects even if unused. Your suggestion does not meet the testability criteria.