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Home > Products > Integrated Circuits (ICs) > Logic > Buffers, Drivers, Receivers, Transceivers

Texas Instruments SN74LS368AN

Name: SN74LS368AN
Brand: Texas Instruments
SKU: SN74LS368AN
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74LS368AN

Manufacturer:: Texas Instruments

Category:: Buffers, Drivers, Receivers, Transceivers

Package:: 16-DIP (0.300", 7.62mm)

Datasheet:: SN74LS368AN.pdf

Description:: IC BUFFER INVERT 5.25V 16DIP

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Product details

Overview

SN74LS368AN from Texas Instruments is a dual 4-bit inverting line driver with three-state outputs, designed for bus-oriented bidirectional data transmission in TTL-level digital systems. It features 16-pin PDIP packaging, operates from 0°C to 70°C, supports ±20 mA output drive, and provides independent output-enable control per group. It is used in legacy industrial control backplanes and microprocessor address/data bus buffering.

For engineers reviewing the SN74LS368AN datasheet, SN74LS368AN pinout, SN74LS368AN application, or SN74LS368AN equivalent, key selection criteria include its dual-group three-state architecture, TTL-compatible input thresholds, guaranteed high-impedance off-state, and compatibility with SN74LS367A/SN74LS365A family timing and drive specifications.

Technical Context

The SN74LS368AN implements two independent 4-bit inverting buffers, each with active-low output-enable (OE) control. Each group's four outputs enter high-impedance state when its respective OE is high, enabling bidirectional bus sharing without external direction logic.

It uses standard TTL bipolar transistor-transistor logic with Schottky clamping for speed optimization. Input thresholds are V_IL ≤ 0.8 V and V_IH ≥ 2.0 V; output low voltage is specified at V_OL ≤ 0.5 V @ I_OL = 20 mA, and output high voltage is V_OH ≥ 2.7 V @ I_OH = 0.4 mA.

Key Specifications

Parameter	Value and Actual Design Meaning
Logic Family	LS-TTL - ensures compatibility with legacy 74LS-series systems and predictable propagation delay under load.
Function	Dual 4-bit inverting three-state buffer - enables two independent 4-bit data paths with polarity inversion and bus contention avoidance.
Supply Voltage	V_CC = 4.75 V to 5.25 V - tight tolerance ensures stable operation across industrial power rails and reduces noise margin degradation.
Output Drive	±20 mA sink/source - sufficient to drive multiple TTL inputs or short PCB traces without external buffering.
Propagation Delay	t_PLH/t_PHL = 15 ns max @ V_CC = 5 V, C_L = 15 pF - supports reliable operation up to ~33 MHz clock domains in synchronous bus interfaces.
Operating Temperature	0°C to 70°C - commercial-grade rating suitable for enclosed industrial controllers and non-military embedded equipment.
Package	16-pin PDIP (N) - through-hole mounting compatible with wave soldering and manual prototyping; 0.3″ wide body.

Pinout & Package

SN74LS368AN is supplied in a 16-pin plastic dual in-line package (PDIP-N), 0.3″ wide, with 0.1″ pin spacing. Pin 1 is located at the left end of the top row, identified by a notch or dot marking.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3, 4	Group A Inputs	Inverting data inputs for first 4-bit channel; logic high yields low output when enabled.
5	Group A Output Enable (Active-Low)	Drives all Group A outputs into high-Z when logic high; enables inverted outputs when low.
6, 7, 9, 10	Group A Outputs	Inverted buffered outputs for pins 1–4; tri-stated when pin 5 is high.
11, 12, 13, 14	Group B Inputs	Inverting data inputs for second 4-bit channel; functionally identical to pins 1–4.
15	Group B Output Enable (Active-Low)	Independent enable for Group B; allows asymmetric bus arbitration between channels.
16	V_CC	+5 V supply connection; decoupling capacitor required within 1 cm for noise immunity.
8	GND	Signal reference plane; must be connected to low-inductance ground plane to minimize switching noise.

Key Features

Feature	Design Value
Independent dual-group three-state control	Enables time-multiplexed use of shared bus lines without external direction logic or arbitration circuitry.
LS-TTL compatible input thresholds	Guarantees interoperability with 74LS, 74S, and 74F families while maintaining noise margins >0.4 V.
High-current output capability	±20 mA drive supports fan-out of up to 20 standard TTL loads per output, reducing need for bus repeaters.
Matched propagation delays between groups	Ensures synchronized enable/disable transitions across both 4-bit channels for glitch-free bus handoff.
RoHS-compliant lead finish	NiPdAu plating on leads meets JEDEC J-STD-609 Category 1 requirements for lead-free assembly compatibility.

Applications

Microprocessor Address Bus Buffering	Legacy Industrial Backplane Interface
Use Scenario: Isolating and driving 16-bit address lines from a Z80 or 8085 CPU to peripheral decoder ICs across a 15 cm PCB trace run. IC Role / Device Role / Timing Role: Inverting three-state buffer providing level-shifting, current gain, and bus contention protection during DMA cycles. Use Value: Eliminates signal integrity issues caused by capacitive loading; enables clean address latching without added glue logic.	Use Scenario: Interfacing multiple 8-bit data acquisition modules to a central controller via shared parallel bus in an oil-field PLC rack. IC Role / Device Role / Timing Role: Bidirectional data path isolator with per-module enable control, allowing one module to transmit while others remain high-Z. Use Value: Reduces inter-module crosstalk and prevents bus collisions without requiring master-side direction control signals.
Test Equipment Signal Conditioning	Avionics Maintenance Interface Adapter
Use Scenario: Converting logic-level signals from FPGA-based test pattern generators to drive legacy TTL-based DUT interface boards. IC Role / Device Role / Timing Role: Level translator and drive amplifier ensuring full logic swing and fast edge rates into 50 Ω terminated lines. Use Value: Maintains <15 ns propagation delay consistency across all 8 driven lines, preserving test vector timing accuracy.	Use Scenario: Adapting ground-support equipment diagnostics ports to legacy flight computer backplanes using MIL-STD-1553 auxiliary buses. IC Role / Device Role / Timing Role: Isolation buffer preventing ground loop currents and protecting sensitive avionics from ESD events on maintenance cables. Use Value: Provides robust ±2 kV HBM ESD protection (inherent to LS process) and eliminates false triggers during hot-plug operations.

Microprocessor Address Bus Buffering

Legacy Industrial Backplane Interface

Use Scenario: Isolating and driving 16-bit address lines from a Z80 or 8085 CPU to peripheral decoder ICs across a 15 cm PCB trace run.

IC Role / Device Role / Timing Role: Inverting three-state buffer providing level-shifting, current gain, and bus contention protection during DMA cycles.

Use Value: Eliminates signal integrity issues caused by capacitive loading; enables clean address latching without added glue logic.

Use Scenario: Interfacing multiple 8-bit data acquisition modules to a central controller via shared parallel bus in an oil-field PLC rack.

IC Role / Device Role / Timing Role: Bidirectional data path isolator with per-module enable control, allowing one module to transmit while others remain high-Z.

Use Value: Reduces inter-module crosstalk and prevents bus collisions without requiring master-side direction control signals.

Test Equipment Signal Conditioning

Avionics Maintenance Interface Adapter

Use Scenario: Converting logic-level signals from FPGA-based test pattern generators to drive legacy TTL-based DUT interface boards.

IC Role / Device Role / Timing Role: Level translator and drive amplifier ensuring full logic swing and fast edge rates into 50 Ω terminated lines.

Use Value: Maintains <15 ns propagation delay consistency across all 8 driven lines, preserving test vector timing accuracy.

Use Scenario: Adapting ground-support equipment diagnostics ports to legacy flight computer backplanes using MIL-STD-1553 auxiliary buses.

IC Role / Device Role / Timing Role: Isolation buffer preventing ground loop currents and protecting sensitive avionics from ESD events on maintenance cables.

Use Value: Provides robust ±2 kV HBM ESD protection (inherent to LS process) and eliminates false triggers during hot-plug operations.

Equivalent & Alternatives

The following parts are listed as comparable options for similar inverting three-state buffer applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74LS367AN	Non-inverting output logic; otherwise identical pinout, timing, and drive specs.	Used where signal polarity preservation is required (e.g., direct connection to non-inverting latches).	Select SN74LS367AN when system logic requires true (non-inverted) data transfer; verify downstream logic accepts non-inverted inputs.
SN74LS240N	Octal inverting three-state buffer (8-bit, single enable); different pinout and enable architecture.	Suitable for unidirectional 8-bit buses where dual-group control is unnecessary.	Choose SN74LS240N for simpler 8-bit-only designs; avoid if dual independent enables or 4-bit granularity are required.

Compared with SN74LS367AN and SN74LS240N, the SN74LS368AN uniquely provides dual 4-bit inverting channels with separate enables-critical for time-sliced bidirectional bus arbitration in legacy multiprocessor systems where polarity inversion is acceptable or required.

Availability

SN74LS368AN is available at Aetrix Electronics and suitable for industrial control backplanes, legacy test equipment interfaces, and avionics maintenance adapters requiring stable component supply and long-term obsolescence management.

Supply support for SN74LS368AN includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader with over 90 years of analog and logic IC innovation, serving industrial, automotive, and aerospace markets with high-reliability components.

The SN74LS368AN belongs to TI's legacy 74LS logic family, engineered for robust performance in noise-prone industrial environments and backward compatibility with 1970s–1990s digital systems architecture.

FAQ

What is the primary function of the SN74LS368AN?

The SN74LS368AN is a dual 4-bit inverting three-state buffer IC. It provides two independent groups of four inverting outputs, each controlled by its own active-low output-enable input. This architecture allows bidirectional bus sharing in TTL systems without external direction logic. Its design ensures compatibility with legacy 74LS-family timing and drive characteristics, making it suitable for address/data bus isolation in microprocessor-based industrial controllers.

Can SN74LS368AN be used as a direct replacement for SN74LS367AN?

No, SN74LS368AN cannot serve as a direct replacement for SN74LS367AN because their output logic polarities differ: SN74LS368AN inverts inputs, while SN74LS367AN does not. Swapping them would invert critical control or address signals, causing system malfunction. However, they share identical pinouts, timing, drive strength, and enable behavior-so redesigning logic polarity upstream/downstream may allow functional substitution in some cases.

What is the maximum recommended capacitive load for SN74LS368AN outputs?

The SN74LS368AN is characterized for operation with up to 15 pF total load capacitance per output, as specified in its propagation delay test conditions. Driving higher capacitance-such as >50 pF-increases rise/fall times, degrades noise margins, and may cause timing violations in synchronous systems. For heavier loads, TI recommends adding series termination resistors or using dedicated bus transceivers like the SN74LS245 instead of relying solely on the SN74LS368AN.

Does SN74LS368AN support mixed-voltage interfacing, such as 3.3 V logic inputs?

No, SN74LS368AN does not reliably support 3.3 V logic inputs. Its input high threshold (V_IH) is specified at ≥2.0 V minimum, but 3.3 V CMOS outputs may not guarantee sufficient noise margin due to lower V_OH under load and potential VIH/VIL overlap. For robust 3.3 V-to-5 V interfacing, a level-shifting buffer such as the SN74LVC4245A should be used upstream of the SN74LS368AN to ensure valid TTL logic levels and prevent undefined states.

Is SN74LS368AN RoHS compliant and lead-free solder compatible?

Yes, SN74LS368AN is RoHS compliant with NiPdAu (nickel-palladium-gold) lead finish, rated for lead-free reflow per JEDEC J-STD-020 Level-1 at 260°C peak. Its MSL rating is "N/A for Pkg Type" due to PDIP's moisture-insensitive construction, eliminating bake requirements before assembly. The device meets IPC/JEDEC standards for Pb-free manufacturing and is qualified for standard reflow profiles used in modern SMT lines-even though it is a through-hole part often wave-soldered.

SN74LS368AN Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74LS

Package/Case:: 16-DIP (0.300", 7.62mm)

Packaging:: Tube

Product Status:: Active

Logic Type:: Buffer, Inverting

Number of Elements:: 2

Number of Bits per Element:: 2, 4 (Hex)

Input Type:: -

Output Type:: 3-State

Current - Output High, Low:: 2.6mA, 24mA

Voltage - Supply:: 4.75V ~ 5.25V

Operating Temperature:: 0°C ~ 70°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 16-PDIP

SN74LS368AN FAQ

1.How can I place an order for SN74LS368AN through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74LS368AN on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for SN74LS368AN reliable?

The price and inventory of SN74LS368AN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS368AN is usually 5 days.

3.What payment methods are accepted for SN74LS368AN?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS368AN transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74LS368AN?

SN74LS368AN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74LS368AN order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for SN74LS368AN?

For technical support, including SN74LS368AN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS368AN requirements.

6.How does Aetrix verify that SN74LS368AN is sourced from the original manufacturer or authorized distributors?

All SN74LS368AN products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74LS368AN meets industry standards.

7.What is the process for return or replacement of SN74LS368AN?

All SN74LS368AN units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS368AN, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The SN74LS368AN part is unused and in its original packaging.

Return procedure for SN74LS368AN:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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