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74HCT14D

Hex inverting Schmitt trigger, TTL input, 4.5-5.5V, SO14, 18ns propagation

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Manufacturer Part：

74HCT14D

Package：

SO14 (SOT108-1, 8.65 x 3.9 x 1.75 mm)

Description

Product Overview

The 74HCT14D from Nexperia is a hex inverting Schmitt trigger in SO14 package, providing six independent inverters with TTL-compatible input levels and hysteresis for noise immunity.

Key Specifications

Logic Family	74HCT (TTL input levels)
Number of Gates	6 inverters
Supply Voltage	4.5 to 5.5V
Propagation Delay	18ns typical
Output Drive	+-4mA
Input Hysteresis	0.6V typical
Max Frequency	36 MHz
Package	SO14 (SOT108-1)
Operating Temperature	-40 to +125 C

Features

TTL-compatible input switching levels
Schmitt trigger hysteresis for noise immunity
Unlimited input rise and fall times
CMOS low power dissipation
ESD protection exceeds 2000V HBM Latch-up performance exceeds 100mA per JESD78
Compliant with JEDEC standards JESD7A and JESD8C

Applications

Wave and pulse shaping
Astable and monostable multivibrators
Signal conditioning and debouncing
Clock and data signal cleanup

Product Introduction:74HCT14D Product Introduction

The 74HCT14D from Nexperia is a hex inverting Schmitt trigger integrated circuit in an SO14 surface-mount package. It contains six independent inverters, each featuring Schmitt trigger inputs with hysteresis that transform slowly changing input signals into sharply defined, jitter-free output signals. The HCT variant features reduced input threshold levels compatible with TTL logic levels, allowing direct interfacing with TTL outputs while maintaining CMOS output drive levels. The Schmitt trigger action provides a hysteresis window of approximately 0.6V, giving excellent noise immunity and allowing the device to handle slowly rising or falling input signals without oscillation. The device operates from a single 4.5V to 5.5V supply and offers a propagation delay of approximately 18ns. Each output can drive up to +-4mA. ESD protection exceeds 2000V HBM and latch-up immunity exceeds 100mA per JESD78.

Working Principle:74HCT14D Working Principle

The 74HCT14D operates through six independent inverting Schmitt trigger channels: (1) Input stage with hysteresis – Each Schmitt trigger input has two distinct threshold voltages: a higher positive-going threshold (VT+) and a lower negative-going threshold (VT-). The difference between VT+ and VT- is the hysteresis voltage (approximately 0.6V typical). When the input voltage rises past VT+, the output switches low (inverted). When the input falls below VT-, the output switches high. This dual-threshold mechanism ensures that small noise fluctuations within the hysteresis window do not cause output toggling. (2) TTL-compatible thresholds – The HCT variant has its VT+ and VT- thresholds set to match TTL logic levels (approximately 1.4V and 0.8V), enabling direct connection to TTL outputs that may not swing rail-to-rail. (3) CMOS output stage – The output stage uses a complementary CMOS push-pull configuration, providing rail-to-rail output swing with +-4mA drive capability. The CMOS construction ensures very low static power consumption. (4) Protection – Input clamp diodes allow interfacing to voltages exceeding VCC when used with current-limiting resistors. ESD protection circuits and latch-up resistant design ensure robust operation.

Pin Description:74HCT14D Pin Definition and Functions

Pin	Name	Function
1	1A	Input of inverter 1
2	1Y	Output of inverter 1
3	2A	Input of inverter 2
4	2Y	Output of inverter 2
5	3A	Input of inverter 3
6	3Y	Output of inverter 3
7	GND	Ground (0V)
8	4Y	Output of inverter 4
9	4A	Input of inverter 4
10	5Y	Output of inverter 5
11	5A	Input of inverter 5
12	6Y	Output of inverter 6
13	6A	Input of inverter 6
14	VCC	Supply voltage (4.5-5.5V)

Application Scenarios:In which products and applications is74HCT14D used

Wave and pulse shaping circuits converting slowly varying analog signals into clean digital outputs with hysteresis noise immunity
Astable and monostable multivibrator circuits using Schmitt trigger hysteresis for precise timing
Switch debouncing and signal conditioning for mechanical contacts with unlimited input rise/fall time tolerance
Clock and data signal cleanup in mixed TTL/CMOS systems leveraging TTL-compatible input thresholds

Alternative Models:What chips are recommended as replacements for 74HCT14D

Model	Manufacturer	Key Difference
74HC14D	Nexperia	CMOS input levels, same function
SN74HCT14N	TI	DIP-14 package, same function
74AHC14D	Nexperia	Faster propagation, overvoltage tolerant
MC74HCT14ADR2G	onsemi	SOIC-14, equivalent