74LS14 Hex Schmitt-trigger inverter
The 74LS14 holds six inverters with Schmitt-trigger inputs. Each input switches high at about 1.6 V and back low at about 0.8 V, and that gap — the hysteresis — turns a slow or noisy signal into a clean, fast edge. Its pinout is the same as the 74LS04.
74LS14 pinout
Top view of the 14-pin DIP package. Pin 1 is at the bottom left, beside the notch, and the numbers run anticlockwise. Power is on pin 14 (VCC, +5 V) and pin 7 (GND).
| Pin | Name | Type | What it is |
|---|---|---|---|
| 1 | 1A | Input | Input |
| 2 | 1Y | Output | Totem-pole output |
| 3 | 2A | Input | Input |
| 4 | 2Y | Output | Totem-pole output |
| 5 | 3A | Input | Input |
| 6 | 3Y | Output | Totem-pole output |
| 7 | GND | Ground | 0 V |
| 8 | 4Y | Output | Totem-pole output |
| 9 | 4A | Input | Input |
| 10 | 5Y | Output | Totem-pole output |
| 11 | 5A | Input | Input |
| 12 | 6Y | Output | Totem-pole output |
| 13 | 6A | Input | Input |
| 14 | VCC | Power | +5 V supply |
74LS14 function table
| A | Y |
|---|---|
| 0 | 1 |
| 1 | 0 |
The input must rise past about 1.6 V to count as 1, and fall below about 0.8 V to count as 0 again.
What the 74LS14 is used for
- Debouncing a push button or switch with an RC filter
- Cleaning up a slow or noisy signal before it reaches a counter
- A simple RC oscillator from one inverter, one resistor and one capacitor
Electrical summary
| Package | 14-pin DIP |
| Supply voltage | 5 V (4.75 V to 5.25 V) |
| Output type | Totem-pole — drives both high and low |
| Output current, low | sinks up to 8 mA |
| Output current, high | sources up to 0.4 mA |
| Input current, low | 0.4 mA out of each input held low |
| Fan-out | one output can drive about 20 LS inputs |
Typical figures for quick reference when planning a board. Check the manufacturer's datasheet for limits and timing before committing a design. The 74HC14 and 74HCT14 use the same pin numbers, with different electrical values.
The 74LS14 and the Breadboard Simulator
The 74LS14 is not in the Breadboard Simulator's parts library yet — this page is a reference. The simulator seats the gates, decoders, multiplexers, adders and buffers marked on the chips page, so the logic around a 74LS14 can be planned and wired there.