# ANSI Schmitt-trigger NAND gate

Canonical URL: https://eloragrid.ai/symbols/ansi-schmitt-nand-gate
Publisher: Elora Grid
Updated: 2026-10-28
Lookup label: NAND-ST
Drawing use: Schematic
Reference families: IEEE / ANSI, Manufacturer

## Symbol convention

Convention: IEEE / ANSI
Form: NAND outline containing the hysteresis mark
Distinctive-shape form as used in IEEE/ANSI-style schematics and manufacturer data books. Independent educational drawing; exact standard geometry and compliance are not asserted.

NAND outline with a hysteresis mark inside, combining the NAND function with Schmitt-trigger inputs.

## In plain English

### What does ANSI Schmitt-trigger NAND gate mean?

A Schmitt-trigger NAND is drawn as a normal NAND outline with the hysteresis mark inside the body. Each input switches at different rising and falling thresholds, so the gate accepts slow or noisy signals while still performing the NAND function.

### A simple example

These gates are often used for gated oscillators, where one input enables an RC oscillator built around the gate, and for combining a debounced contact with an enable signal. Timing components should be drawn close to the gate with the intended frequency or delay noted.

### What the drawings help you do

Threshold levels and hysteresis width are not shown by the symbol and differ between logic families. Read them from the device documentation.

### This particular reference

NAND outline with a hysteresis mark inside, combining the NAND function with Schmitt-trigger inputs. A standard NAND has no hysteresis mark and a single threshold.

### Terms

- Normally open / normally closed: The contact state in the normal condition defined for the drawing.
- Signal: Electrical information passed between devices, rather than necessarily the main power supply.
- Schematic: A drawing showing function and connections rather than physical appearance.

Concept diagram: Identify the device and form → Read the connections and state → Check the equipment reference
A guide to reading this reference. The original symbol illustration and its drawing notes appear below; these boxes are not a wiring diagram.

- [SNx4HC132 quadruple 2-input NAND gates with Schmitt-trigger inputs](https://www.ti.com/lit/ds/symlink/sn74hc132.pdf)


## What it represents

A Schmitt-trigger NAND is drawn as a normal NAND outline with the hysteresis mark inside the body. Each input switches at different rising and falling thresholds, so the gate accepts slow or noisy signals while still performing the NAND function.
These gates are often used for gated oscillators, where one input enables an RC oscillator built around the gate, and for combining a debounced contact with an enable signal. Timing components should be drawn close to the gate with the intended frequency or delay noted.
Threshold levels and hysteresis width are not shown by the symbol and differ between logic families. Read them from the device documentation.

## How to read it

- Spot the hysteresis mark inside the NAND body.
- Check for RC components that create an oscillator.

## Information to show or reference

- Show the hysteresis mark within the outline.
- Keep timing components adjacent.
- State the intended oscillator frequency or debounce time.

## Important distinction

A standard NAND has no hysteresis mark and a single threshold.

## Facts

- Function: NAND with Schmitt-trigger inputs
- Common use: Gated RC oscillator, debounced enable
- Artwork scope: Original educational illustration; consult the applicable standard and the selected device documentation for the exact graphic

## Public references

- [SNx4HC132 quadruple 2-input NAND gates with Schmitt-trigger inputs](https://www.ti.com/lit/ds/symlink/sn74hc132.pdf) — Texas Instruments. Manufacturer documentation for NAND gates with Schmitt-trigger inputs.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.