4093 Quad 2-Input NAND Schmitt Trigger

Description

4093 – An IC with Four Schmitt Trigger NAND Gates

The 4093 is a CMOS chip with four NAND gates with a Schmitt trigger. Because each gate has two inputs and has four gates inside, it’s often referred to as a
Quad 2-Input NAND Schmitt Trigger
.

A NAND gate with a Schmitt trigger works more or less like a normal NAND gate. With the exception that the threshold for when it switches from LOW to HIGH is different from when it switches from HIGH to LOW.

Pin Overview

Pin Name

Pin #

Type

Description

VDD

14

Power

Supply Voltage (+3 to +15V)

GND

7

Power

Ground (0V)

A1 to A4

1, 5, 8, 12

Input

Inputs A of the four NAND gates

B1 to B4

2, 6, 9, 13

Input

Inputs B of the four NAND gates

Q1 to Q4

3, 4, 10, 11

Output

Outputs from the four NAND gates

Pin overview for the 4093 IC

What is a NAND gate with Schmitt Trigger?

First of all, a NAND gate is a logic gate that works like an AND gate with a NOT gate on the output. Therefore it’s often called NOT-AND.

A NAND gate built from AND and NOT gates

This means that a NAND gate gives a LOW output only when all inputs are HIGH as shown in the truth table below.

Input A

Input B

Output Q

0

0

1

1

0

1

0

1

1

1

1

0

Truth Table for the NAND gate

Schmitt Trigger

But this is a Schmitt trigger NAND gate. What does that mean?

This has to do with at what voltage the gate will interpret the input as a LOW or a HIGH input:

For example for a normal (non-Schmitt Trigger) gate that is powered from 5V, the gate might say that any voltage above 2.5V is HIGH, and any voltage below 2.5V is LOW. So if the input is at 2.5V and swinging a bit up and down (as these signals tend to do), then the output would be uncertain.

2.5V would be the
threshold voltage
.

But for a Schmitt trigger gate, the threshold voltage is different based on if the input changes from LOW to HIGH or from HIGH to LOW.

For example, if the input is currently LOW, then a Schmitt trigger gate might require the input voltage to go above for 3.5V to switch to HIGH. But when it has switched to HIGH, dropping a bit below 3.5V doesn’t matter. Because in order to switch back to LOW, the Schmitt trigger gate requires the input to go down below for example 1.5V.

Technical Specifications

Physical

Case/Package

PDIP

Contact Plating

Gold

Mount

Through Hole

Number of Pins

14

Technical

High Level Output Current

-4.2 mA

Logic Function

NAND, Schmitt Trigger

Low Level Output Current

4.2 mA

Max Operating Temperature

125 °C

Max Output Current

6.8 mA

Max Supply Voltage

18 V

Manufacturer Package Identifier

J (R-GDIP-T**)

Min Operating Temperature

-55 °C

Min Supply Voltage

3 V

Number of Bits

4

Number of Channels

4

Number of Circuits

4

Number of Elements

4

Number of Gates

4

Number of Input Lines

2

Number of Inputs

2

Number of Output Lines

1

Number of Outputs

1

Output Current

6.8 mA

Propagation Delay

130 ns

Quiescent Current

20 µA

Schmitt Trigger Input

Yes

Termination

Through Hole

Turn-On Delay Time

380 ns

4093 Datasheet