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74HC04 Hex Inverter

Six plain inverters. The cheapest logic chip there is, and the wrong one if your input edge is slow.

Cheat sheet (SVG)

Logic level: 2-6 V (HC)
Package: PDIP-14 / SOIC-14

1.Pinout diagram

Highlight a signalhover to preview, click to keep

Pins 1-7

74HC04

Pins 8-14

Pin detail

Hover a pin for its mappings and gotchas. Click to keep it here.

Logic level: 2-6 V (HC)
Package: PDIP-14 / SOIC-14

Fig. 1. 74HC04 Hex Inverter, PDIP-14. Hover or tap a signal to light up every pin that carries it.

2.Watch out

No hysteresis. A slow or noisy edge makes the output chatter through the transition, sometimes several times. If the input comes from an RC, a long cable, a sensor or a switch, use the 74HC14 instead.
Same pin arrangement as the 74HC14, so the two are interchangeable in a socket. The 14 is a strict upgrade for about the same money.
Tie unused inputs to a rail. Six floating inverter inputs will happily oscillate and heat the chip.
Two inverters and an RC make a ring oscillator, but without hysteresis it is jittery. Again, the 74HC14 does this properly.

3.Crystal oscillator

What has to go around the chip before it will run.

Fig. 2. Crystal oscillator, drawn from Table 1. Crossing wires are not connected.

Table 1. External parts, and why each one is there.
Part	Between	Why
1 MOhm	1A (1) to 1Y (2)	Biases the inverter into its linear region so it amplifies instead of sitting at a rail.
Crystal	1A (1) to 1Y (2)	A fundamental-mode crystal across the same inverter. This is the Pierce oscillator.
22 pF	1A (1) to GND	Load capacitor on the input side. The crystal's datasheet load, usually 18 to 22 pF.
22 pF	1Y (2) to GND	The matching load capacitor on the output side.
100 nF	VCC (14) to GND	Supply decoupling at the pin.

Buffer the output with a second inverter before you use it anywhere, so loading the oscillator does not pull it off frequency. An HCU04, the unbuffered version, oscillates more reliably here than the HC04.

4.Full pin reference

Every pin, alias and mapping. This is the table that prints.

Table 2. Pin assignments.

Complete pin reference for 74HC04 Hex Inverter
Pin	Name	Also called	Functions	Notes
1	1A	-	Inverter 1 input
2	1Y	-	Inverter 1 output
3	2A	-	Inverter 2 input
4	2Y	-	Inverter 2 output
5	3A	-	Inverter 3 input
6	3Y	-	Inverter 3 output
7	GND	-	Ground
8	4Y	-	Inverter 4 output	Output first on this side.
9	4A	-	Inverter 4 input
10	5Y	-	Inverter 5 output
11	5A	-	Inverter 5 input
12	6Y	-	Inverter 6 output
13	6A	-	Inverter 6 input
14	VCC2-6 V	-	Positive supply	100 nF at the pin.

Looking for a substitute?

74HC04, 4 alternatives

Primary sources

TI SN74HC04 datasheet ↗

Found a wrong pin? The whole board is one file, data/boards/sn74hc04.json.

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