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

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
7400	Quad 2-input NAND gate
7401	Quad 2-input NAND gate; open collector outputs
7402	Quad 2-input NOR gate
7403	Quad 2-input NAND gate; open collector outputs
7404	Hex inverter
7405	Hex inverter; open collector outputs
7406	Hex inverter; open collector high voltage outputs
7407	Hex buffer; open collector high voltage outputs
7408	Quad 2-input AND gate
7409	Quad 2-input AND gate; open collector outputs
7410	Triple 3-input NAND gate
7411	Triple 3-input AND Gate
7412	Triple 3-input NAND gate; open collector outputs
7413	Dual 4-input NAND Schmitt triggers
7414	Hex Schmitt-trigger inverter
7415	Triple 3-Input AND gate; open collector outputs
7416	Hex Inverter/Driver; open collector 15V outputs
7417	Hex Buffer/Driver; open collector 15V outputs
7418	Dual 4-input NAND gate with Schmitt trigger inputs
7419	Hex Schmitt trigger Inverter
7420	Dual 4-input NAND gate; open collector 15V outputs
7421	Dual 4-input AND gate; open collector 15V outputs
7422	Dual 4-input NAND gate; open collector 15V outputs
7423	Dual 4-input NOR gate with strobe
7424	Quad 2-input NAND gate with Schmitt trigger inputs
7425	Dual 4-input NOR gate with strobe
7426	Quad 2-input NAND gate; open collector 15V outputs
7427	Triple 3-input NOR gate
7428	Quad 2-input NOR gate
7429
7430	8-Input NAND gate
7431	Hex delay elements
7432	Quad 2-input OR gate
7433	Quad 2-input NOR gate; open collector outputs
7434	Hex non-Inverter
7435	Hex non-Inverter; open collector outputs
7436	Quad 2-input NOR gate (Different pinout)
7437	Quad 2-input NAND gate (Different pinout)
7438	Quad 2-input NAND gate; open collector outputs
7439	Quad 2-input NAND gate; open collector outputs (Different pinout)
7440	Dual 4-input NAND Gates