Overview

The 74HC04 (SN74HC04) is a hex inverter IC manufactured using high-speed silicon-gate CMOS technology. Containing six independent inverting gates (NOT gates) in a 14-pin DIP/SOIC package, it performs the Boolean function Y=A‾Y = \overline{A} in positive logic.

Operating across a supply voltage range of 2.0V to 6.0V DC, it combines low CMOS power consumption with high-speed switching speeds (7 ns7\text{ ns} propagation delay). The 74HC04 is used everywhere in digital electronics for signal polarity inversion, square-wave clock generators, RC delay timing circuits, and crystal oscillators.

Quick reference

Supply Voltage (VCC)2.0 V to 6.0 V DC
Logic FamilyHigh-Speed CMOS (74HC) / TTL Compatible (74HCT) / Unbuffered (74HCU)
Independent Inverters6 (Hex Inverter)
Propagation Delay7 ns7\text{ ns} typical at VCC=5.0VVCC = 5.0\text{V}
Output Drive Current±5.2 mA\pm 5.2\text{ mA} at VCC=4.5VVCC = 4.5\text{V}
Package14-pin DIP / SOIC-14 / TSSOP-14

Pinout (DIP-14 Package)

text
             ┌───┴───┐
          1A 1│ 1   14│ VCC
          1Y 2│       │13 6A
          2A 3│       │12 6Y
          2Y 4│ 74HC04│11 5A
          3A 5│       │10 5Y
          3Y 6│       │9  4A
         GND 7│       │8  4Y
             └───────┘
PinNameDescription
11AInverter 1 Input
21YInverter 1 Output (1Y=1A‾1Y = \overline{1A})
32AInverter 2 Input
42YInverter 2 Output (2Y=2A‾2Y = \overline{2A})
53AInverter 3 Input
63YInverter 3 Output (3Y=3A‾3Y = \overline{3A})
7GNDGround reference (0 V)
84YInverter 4 Output (4Y=4A‾4Y = \overline{4A})
94AInverter 4 Input
105YInverter 5 Output (5Y=5A‾5Y = \overline{5A})
115AInverter 5 Input
126YInverter 6 Output (6Y=6A‾6Y = \overline{6A})
136AInverter 6 Input
14VCCPower supply voltage (+2.0V to +6.0V DC)

Function & Truth Table (Per Gate)

Input AOutput Y
Low (LL)High (HH)
High (HH)Low (LL)

Specifications

ParameterSymbolMinTypMaxUnitConditions
Supply VoltageVCCV_{CC}2.05.06.0VDC
High-Level Input VoltageVIHV_{IH}3.15——VVCC=4.5VV_{CC} = 4.5\text{V}
Low-Level Input VoltageVILV_{IL}——1.35VVCC=4.5VV_{CC} = 4.5\text{V}
Propagation Delay (A→YA \rightarrow Y)tPDt_{PD}—714nsVCC=4.5V,CL=50pFV_{CC} = 4.5\text{V}, C_L = 50\text{pF}
Output Drive CurrentIOUTI_{OUT}——±5.2\pm 5.2mAVCC=4.5VV_{CC} = 4.5\text{V}
Quiescent Supply CurrentICCI_{CC}——2.0µAVIN=VCC or GNDV_{IN} = V_{CC}\text{ or GND}

Typical Applications

Simple Ring Oscillator Clock Generator

Connecting an odd number of inverters (e.g. 3 inverters) in a feedback loop with a capacitor generates a continuous square-wave clock signal.

text
       ┌──────────────────[Feedback Capacitor C]─────────────────┐
       │                                                         │
  ───►[Pin 1: 1A] ──► [Pin 2: 1Y] ──► [Pin 3: 2A] ──► [Pin 4: 2Y] ──┴──► Clock Out

Common mistakes

  • Leaving unused inverter inputs floating: Floating inputs on pins 5, 9, 11, or 13 will drift into intermediate voltage levels, causing the CMOS output stage to enter a linear region where both internal PMOS and NMOS transistors conduct, causing high power consumption and noise. Connect unused input pins to VCCV_{CC} or GND.
  • Using standard 74HC04 instead of 74HCU04 for analog/crystal oscillators: Standard 74HC04 inverters are buffered (high gain triple-stage). For crystal oscillators or analog linear amplifiers, unbuffered 74HCU04 inverters are required to prevent high-frequency self-oscillation.
  • Using 74HC04 as a Schmitt trigger debouncer: Standard 74HC04 inputs lack hysteresis. Slow-changing input signals (such as charging RC circuits or noisy switches) will cause output chattering. Use 74HC14 (Schmitt-Trigger Hex Inverter) for noisy or slow signals.

Notes

  • 74HC04 vs 74HC14 vs 74HCU04: 74HC04 is a standard buffered hex inverter; 74HC14 is a Schmitt-trigger hex inverter (with hysteresis); 74HCU04 is an unbuffered single-stage hex inverter.

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