A series of various 74LS chips.

7400 series is an extended family of digital integrated circuits. Chips in this series include a variety of discrete logic chips chips such as and gates and or gates as well as registers, decoders, and RAM units.

While the original series was designed as TTL logic chips, over the years, a large number of sub-families have been introduced. Generally speaking, parts from the same subfamily can be used freely with other parts from the same subfamily. However, in many cases not with parts from other subfamilies. This is because voltage and current configurations for ICs from the same subfamily are designed so they can be connected without requiring additional work.

Part Identification

HD	54	LS		10
SN	74	HCT	2G	04	N
						Package Designation
					Device Number
				Gates Count
			Technology Indicator
		Specs/Temp Indicator
	Manufacturer Prefix

• Specs/Temp Indicator:

75 - Interface device

74 - Commercial Grade

64 - Industrial

54 - Military/Airspace Grade

• Technology indicator:

Some of more popular ones you'll encounter are:

None - When no indicator is found, this implies it's the original TTL

Bipolar

S - Schottky logic.

LS - Low-power Schottky. Same as L series but with reduced power consumption and switching speed.

CMOS

C - CMOS

AC / ACT - Advanced CMOS (T version for TTL-compatible inputs)

HC / HCT - High-speed CMOS, similar to LS (T version for TTL-compatible inputs)

AHC / AHCT - Advanced high-speed CMOS (T version for TTL-compatible inputs)

LV / LVC' - Low-Voltage CMOS

BiCMOS

BCT - BiCMOS

ABT - Advanced BiCMOS

• Gates Count (surface mount ICs only)

1G = 1, 2G = 2, 3G = 3

• Device Number

00 - NAND 02 - NOR 04 - NOT 08 - AND

10 - 3-input NAND 11 - 3-input AND 20 - 4-input NAND 21 - 4-input AND

25 - 4-input NOR 27 - 3-input NOR 30 - 8-input NAND 32 - 2-input OR

etc.. (full list below)

• Package Designation

D - DIP DB - SSOP

FK - LCCC J - CDIP

N - Plastic DIP NS - SOP

PS - SOP T - Flat package

W - CFP

Example

Chip is labeled DM74LS221N:

DM - prefix - made by Fairchild or National Semiconductor, but given the F logo, we can determine it's Fairchild.

74 - series - commercial grade chip

LS - techno - Low-power Schottky.

221 - device - Dual non-retriggerable monostable multivibrator with reset

N - package - standard plastic DIP

List of Devices

Device Number	Description
00	Quad 2-input NAND gate
01	Quad 2-input NAND gate; open collector outputs
02	Quad 2-input NOR gate
03	Quad 2-input NAND gate; open collector outputs
04	Hex inverter
05	Hex inverter; open collector outputs
06	Hex inverter; open collector high voltage outputs
07	Hex buffer; open collector high voltage outputs
08	Quad 2-input AND gate
09	Quad 2-input AND gate; open collector outputs
10	Triple 3-input NAND gate
11	Triple 3-input AND Gate
12	Triple 3-input NAND gate; open collector outputs
13	Dual 4-input NAND Schmitt triggers
14	Hex Schmitt-trigger inverter