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What to do with unused IC pins?
General “rule of thumb” for unused IC pins
- Provide a solder pad/hole so the chip is secured but leave pin floating.
- Connect the pin to ground (possible through a resistor/capacitor/etc.)
- Connect the pin to a supply source.
- Something I can’t possibly think of.
What does NC mean on an IC?
Not Connected Pin (NC pin) or Not Connected Terminals are pins found on various integrated circuit packages. Those pins have no functional purpose to the outside circuit (but may have unexposed functionality). Those pins should not be connected to any of the circuit connections – i.e. they should be left floating.
What’s the rule of thumb for unused IC pins?
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. “Connect the pin to ground”. That’s a good solution, provided that you can guarantee that the pin will never become an output.
Can a resistor prevent a pin from becoming an output?
That’s a good solution, provided that you can guarantee that the pin will never become an output. Output high and you short-circuit the power supply. A resistor would prevent that, but that’s an extra cost.
What does NC mean on an IC pin?
It is common for an IC to have one or more terminals that are marked “NC” on the pinout diagram. This can mean two different things, and very often the data sheet does not explain which. The more common meaning is that there is no connection from the IC chip to that pin.
Why are my IC pins drawing static power?
Depending on the input circuit, this could cause your pins to float in at a non-digital value, and your IC’s transistors will behave accordingly, drawing more static power than the would otherwise. If the datasheet doesn’t say anything it is likely that there is an app note from the manufacturer that discusses it.