7408

The 7408 is a TTL quad 2-input AND gate integrated circuit in the 7400 family. It contains four independent AND gates, each with two inputs and a single output. It is widely used in digital logic designs to implement basic conjunction operations and is found in many educational, hobbyist, and industrial circuits. The part is manufactured by multiple vendors, including Texas Instruments and Fairchild, and has remained a staple of early and mid-era logic design.

Electrical characteristics and usage: The device operates from a 5-volt supply (Vcc) and uses TTL-compatible inputs. Outputs provide standard TTL logic levels and can source or sink limited current. Inputs should not be left floating, as undefined states can occur. Propagation delay varies by speed grade; typical TTL parts in the 74xx family exhibit delays on the order of a few to tens of nanoseconds depending on the variant and load.

Pinout and packaging: 7408 is commonly available in a 14-pin DIP package, with power pins designated as Vcc on pin 14 and GND on pin 7. The four gates are arranged so that inputs A1 and B1 produce Y1, inputs A2 and B2 produce Y2, inputs A3 and B3 produce Y3, and inputs A4 and B4 produce Y4. The exact pin numbers follow the standard 74xx-08 footprint and should be verified against the supplier’s datasheet.

Variants and compatibility: The 7408 family includes several speed and logic-family variants such as 74LS08, 74HC08, 74HCT08, and 74ACT08. These differ mainly in drive strength, speed, and input/output characteristics, but they implement the same four 2-input AND gates. CMOS variants (e.g., HC family) offer lower power consumption, while TTL variants (e.g., LS, ACT) differ in speed and fan-out characteristics.