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74HC08 Quad AND Gate

Four 2-input AND gates. Same pin arrangement as the 74HC00, so the two get mixed up constantly.

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

74HC08

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. 74HC08 Quad AND Gate, PDIP-14. Hover or tap a signal to light up every pin that carries it.

2.Watch out

AND is the gate you want for a simple enable: data on one input, a control line on the other.
Same pin arrangement as the 74HC00, 74HC32 and 74HC86. The only way to tell them apart on a board is the marking, so check before you assume the logic.
Unused inputs must be tied high or low. A floating CMOS input oscillates and drags supply current.
HC inputs need a level near their own rail. Driving a 5 V part from 3.3 V logic wants the HCT version.

3.Minimum circuit

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

Fig. 2. Minimum circuit, drawn from Table 1. Crossing wires are not connected.

Table 1. External parts, and why each one is there.
Part	Between	Why
Wire link	1B (2) to VCC	One input high turns the gate into a plain buffer for the other. The usual way a spare AND gets used.
Wire link	4A (12) to GND	An unused input cannot be left floating: a CMOS input at mid-rail turns both transistors on and the chip heats up.
Wire link	4B (13) to GND	The other input of the same unused gate. Tie every one of them, not just one per gate.
100 nF	VCC (14) to GND	Supply decoupling at the pin.

Unused inputs are the one thing people skip on a 74HC part and the one thing that produces a warm chip, random outputs and an oscillation nobody can find.

4.Full pin reference

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

Table 2. Pin assignments.

Complete pin reference for 74HC08 Quad AND Gate
Pin	Name	Also called	Functions	Notes
1	1A	-	Gate 1 input A
2	1B	-	Gate 1 input B
3	1Y	-	Gate 1 output (AND)
4	2A	-	Gate 2 input A
5	2B	-	Gate 2 input B
6	2Y	-	Gate 2 output (AND)
7	GND	-	Ground
8	3Y	-	Gate 3 output (AND)	Output comes first on this side.
9	3A	-	Gate 3 input A
10	3B	-	Gate 3 input B
11	4Y	-	Gate 4 output (AND)
12	4A	-	Gate 4 input A
13	4B	-	Gate 4 input B
14	VCC2-6 V	-	Positive supply	100 nF at the pin.

Primary sources

TI 74HC08 datasheet ↗

Found a wrong pin? The whole board is one file, data/boards/sn74hc08.json.

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