74HC14 PCB Design Guide: Footprint, Pinout, and Alternatives

The 74HC14 is the hex Schmitt-trigger inverter: six independent inverting gates whose inputs have built-in hysteresis, 0.9 V typical at VCC = 4.5 V. That hysteresis is the whole product. A plain CMOS gate fed a slow or noisy edge can oscillate while the input dawdles through its threshold region; a Schmitt input switches cleanly once, because the rising and falling trip points are different voltages. TI's SN74HC14 runs from 2 to 6 V, is specified from -40 to 85 C, propagates in 12 ns typical at 4.5 V, and draws 2 uA max static supply current at 25 C, which is why one of these sits in the corner of so many boards squaring up switch inputs, sensor outputs, and RC ramps.

Pick the 74HC14 when the shape of the input edge is the problem: mechanical switches, long cables, oscillator ramps, anything slower or dirtier than logic. Do not pick it when the trip voltage is the specification. The thresholds are guaranteed only loosely, with VT+ anywhere from 1.55 to 3.13 V at VCC = 4.5 V and hysteresis anywhere from 0.4 to 2.1 V, and they scale with the supply, so a Schmitt gate is a signal conditioner, not a comparator. If your edges are already clean, a plain hex inverter does the same logic; if your rail is above the HC family's 6 V limit, the 4000-series CD40106B covers 3 to 18 V. Note also that 74HC14 is a generic part number made by several vendors; every number on this page is verified against the Texas Instruments SN74HC14.

The gotchas below are the recurring board-level mistakes: designing to the typical hysteresis instead of the 0.4 V minimum, expecting the Schmitt input alone to debounce a switch, feeding an input above VCC through the clamp diodes, asking the outputs for more than their 4 mA spec point, and leaving unused inputs floating.

What breaks boards

1. 01

   Thresholds are guaranteed loose: design to the 0.4 V minimum hysteresis

   At VCC = 4.5 V the hysteresis is 0.9 V typical, but the guaranteed window is 0.4 to 2.1 V, with VT+ anywhere from 1.55 to 3.13 V and VT- from 0.9 to 2.45 V. TI's guidance is that the minimum hysteresis is your peak-to-peak noise limit, so budget 0.4 V, not 0.9. The same spread is why the classic single-gate RC oscillator has poor unit-to-unit frequency tolerance, and why its frequency moves with the supply: the thresholds scale with VCC. Use it for LED blinkers and charge-pump clocks; use a timer, crystal, or MCU timer when frequency matters.

2. 02

   A Schmitt input is not a debouncer

   Hysteresis rejects noise smaller than the minimum band, 0.4 V peak-to-peak at 4.5 V. A bouncing switch contact swings the full rail, so every bounce crosses both thresholds and exits as a clean, full-speed pulse, which is exactly what your counter did not want. TI's listed switch-debounce application works because the RC network in front of the gate does the actual debouncing: the capacitor keeps the input from recrossing the thresholds during the bounce window, and the Schmitt input's job is to turn that slow RC ramp into one sharp edge without oscillating.

3. 03

   Inputs are not 5 V tolerant: respect the clamp diodes

   Every input and output has clamp diodes to VCC and GND, and the absolute maximum input clamp current is +/-20 mA whenever VI < 0 or VI > VCC. Feed a 5 V signal into a gate running from a lower rail and the top diode conducts, injecting current into that rail; a lightly loaded rail can get dragged upward, and the same path back-powers an unpowered board through any driven input. Either run the 74HC14 from the higher rail (6 V max recommended, 7 V absolute max) or level-shift; a series resistor sized to keep clamp current under 20 mA is the minimum fix.

4. 04

   Outputs are specced at 4 mA; 25 mA per pin and 50 mA per package are damage limits

   The numbers you can design against sit at 4 mA: VOH 3.98 V min at IOH = -4 mA and VOL 0.26 V max at IOL = 4 mA (VCC = 4.5 V, 25 C). The +/-25 mA continuous output current is an absolute maximum, not an operating point, and the whole package is limited to +/-50 mA through VCC or GND, so two outputs at the pin limit already exceed the package budget. Sum LED currents across all six gates against the 50 mA total, and remember the balanced CMOS output drives fast edges into light loads: long unterminated traces will ring.

5. 05

   Tie unused inputs; bypass every VCC pin

   Unused inputs must be terminated at VCC or GND. A Schmitt input held between levels does not draw the large shoot-through current a standard CMOS input would, but a floating input still leaves the gate in an undefined state, and slowly driven inputs raise dynamic supply current; the 2 uA max static ICC is specified with inputs at VCC or ground. Unused outputs may be left floating, but never tie an output directly to VCC or ground. Give the supply pin a 0.1 uF bypass capacitor installed as close to the power terminal as possible, since six switching gates share it.

Key specifications

Verified against the manufacturer datasheet on 2026-07-10. Confirm the current revision before production use.

Alternatives

• SN74HCS14: TI's newer HCS-family drop-in with the same Schmitt-trigger inputs and lower static supply current; usually the better pick for a new design if pricing and stock cooperate.
• SN74AHC14: TI's faster, lower-power AHC-family hex Schmitt inverter. Check your rail first: AHC is not rated to 6 V like HC.
• CD40106B: TI's 4000-series hex Schmitt inverter for supplies above the HC family's 6 V limit (wide 3-18 V VCC); slower than HC, but the option when the logic must live on a higher rail.
• 74HC14D (Nexperia): pin- and function-compatible second source for the same generic. The numbers on this page are verified against the TI SN74HC14 only; Nexperia's limits differ in detail, so re-check its datasheet before treating them as interchangeable at the margins.

Common questions

Can the 74HC14 run from a supply below 5 V?

Yes. Recommended VCC is 2 V min to 6 V max, so the common low-voltage logic rails are all in range, with two consequences. First, the thresholds scale with the supply and the guaranteed hysteresis shrinks toward the low-supply numbers (0.2 V min at VCC = 2 V versus 0.4 V min at 4.5 V). Second, inputs must not exceed VCC, so a 5 V signal into a gate on a lower rail forward-biases the clamp diode. Speed also derates: propagation delay is 12 ns typ / 25 ns max at 4.5 V but slows to 55 ns typ / 125 ns max at the 2 V corner.

What is the difference between a 74HC04 and a 74HC14?

Both are hex inverters with the same logic function; the 74HC14 adds Schmitt-trigger inputs with guaranteed hysteresis (0.4 V min at VCC = 4.5 V). That gives it no input transition-rate requirement: arbitrarily slow or noisy edges produce one clean output transition, where a plain inverter fed a slow edge can oscillate and draw extra supply current while the input sits in its threshold region. If every signal on the board is already fast, clean logic, either works; when an input comes from a switch, a cable, or an RC, use the 74HC14.

Can I debounce a switch with a 74HC14 alone?

No. The Schmitt input rejects noise only up to its minimum hysteresis, 0.4 V peak-to-peak at 4.5 V, and switch bounce swings rail to rail, so each bounce comes out as a clean full pulse. Put an RC in front of the gate, sized so the input cannot recross the thresholds during the bounce window; the 74HC14 then squares the slow RC ramp into one sharp edge. That RC-plus-Schmitt combination is the debounce circuit TI lists as a typical application, not the bare gate.

How much current can a 74HC14 output source or sink?

Design to the 4 mA spec point: VOH is 3.98 V min at IOH = -4 mA and VOL is 0.26 V max at IOL = 4 mA (VCC = 4.5 V, 25 C). The absolute maximums are +/-25 mA continuous per output and +/-50 mA total through VCC or GND for the whole package, and those are damage limits, not operating points. One indicator LED with a sensible series resistor per gate is workable; six LEDs driven hard at once runs into the 50 mA package budget.