One Inverter#

The problem is small and extremely common: a design needs exactly one inverter — to flip an active-low signal to active-high, correct a polarity, or generate a complement — and nothing else. Dropping a 14-pin hex inverter to use one-sixth of it is wasteful on a modern board.

The Part#

Reach for a single-gate (“tiny logic”) inverter: the 74LVC1G04 in a tiny SOT-23-5 or smaller package, running at low voltage with 5 V-tolerant inputs. On an all-5 V board the classic 74HC04 hex inverter still works if the extra five gates can be spared or reused elsewhere. If the signal is also slow or noisy, use the Schmitt-trigger version (74LVC1G14 / 74HC14) and get debounce-grade edge cleaning in the same part.

Alternatives and Cautions#

• A spare gate you already have — an unused NAND or NOR in an existing package makes an inverter (tie its inputs together). Free, if one is going spare.
• A single transistor and resistor — the RTL inverter still works for a quick discrete fix, at the cost of drive and speed.
• The firmware, if a pin is handy — sometimes the cheapest inverter is not inverting in hardware at all, but flipping the logic in the microcontroller.

Whichever route, tie the inputs of any unused gates in a package to a rail — never leave CMOS inputs floating, or they draw current and pick up noise.