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

STMicroelectronics 74AC240TTR

Name: 74AC240TTR
Brand: STMicroelectronics
SKU: 74AC240TTR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 74AC240TTR

Manufacturer:: STMicroelectronics

Category:: Buffers, Drivers, Receivers, Transceivers

Package:: 20-TSSOP (0.173", 4.40mm Width)

Datasheet:: 74AC240TTR.pdf

Description:: IC BUFF INVERT 6V 20TSSOP

Quantity:: RFQ Add To RFQ list

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Inventory:3,862

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Product details

Overview

74AC240TTR from STMicroelectronics is an advanced high-speed CMOS octal bus buffer with 3-state inverted outputs, designed for memory address driving and bidirectional bus interfacing. It operates from 2V to 6V, delivers symmetrical 24mA drive capability, exhibits 4.2ns typical propagation delay at 5V, and features dual independent output-enable controls (1G, 2G) for grouped channel management in industrial control backplanes.

For engineers reviewing the 74AC240TTR datasheet, 74AC240TTR pinout, 74AC240TTR application, or 74AC240TTR equivalent, key selection criteria include its 50Ω transmission line driving capability, ±24mA balanced output current, latch-up immunity, ESD tolerance (2kV), and TSSOP-20 package compatibility with space-constrained PCB layouts.

Technical Context

The device integrates eight inverting buffers split into two independently enabled groups (1Y1–1Y4 and 2Y1–2Y4), each controlled by dedicated active-low enable inputs (1G, 2G). Its C2MOS fabrication enables rail-to-rail input voltage tolerance (0–VCC) and low quiescent ICC of 4µA max at 25°C.

Propagation delays are tightly balanced (tPLH ≅ tPHL), and output impedance is symmetrical-ensuring clean signal integrity on 50Ω transmission lines. Input noise immunity is guaranteed at ≥28% VCC across the full operating temperature range (–55°C to +125°C).

Key Specifications

Parameter	Value and Actual Design Meaning
VCC Range	2V to 6V - supports mixed-voltage system interfacing including 3.3V and 5V logic domains
tPD (Typ.)	4.2ns at VCC = 5V - enables high-speed address/data buffering in microcontroller peripheral buses
IOL / IOH	24mA min - drives standard 50Ω transmission lines without external termination resistors
VNIH / VNIL	28% VCC min - ensures robust noise rejection in electrically noisy industrial environments
ICC (Max)	4µA at TA = 25°C - ultra-low static power for always-on bus isolation circuits
ESD Immunity	2kV HBM - protects against handling-induced discharge during assembly and field service
Operating Temp	–55°C to +125°C - qualified for extended-temperature automotive and industrial control applications

Pinout & Package

TSSOP-20 package: 6.5mm × 4.4mm body, 0.65mm pitch, thin-profile surface-mount construction with exposed pad not present; RoHS-compliant matte tin lead finish.

Pin/Terminal	Circuit Role	Design Meaning
1, 19	Output Enable (1G, 2G)	Active-low group enable controls - allows time-multiplexed access to two 4-bit data paths
2,4,6,8 / 11,13,15,17	Data Inputs (1A1–1A4, 2A1–2A4)	Inverting input terminals - logic inversion occurs before 3-state output gating
3,5,7,9 / 12,14,16,18	Data Outputs (1Y1–1Y4, 2Y1–2Y4)	Inverted, 3-state outputs - high-impedance state isolates bus segments when G = HIGH
10	GND	Signal reference and return path - must be low-inductance connection to minimize ground bounce
20	VCC	Positive supply - decoupling capacitor (100nF) required within 5mm of this pin

Key Features

Feature	Design Value
Inverted 3-state outputs	Enables bidirectional bus arbitration via complementary enable control without external inverters
Symmetrical output drive	\|IOH\| = IOL = 24mA min - eliminates timing skew between rising/falling edges on shared lines
50Ω line driving	Guaranteed performance on controlled-impedance PCB traces - reduces need for series termination
High noise immunity	VNIH/VNIL ≥ 28% VCC - maintains logic integrity in motor-drive or relay-switching proximity
Latch-up immunity	Improved over standard CMOS - prevents destructive parasitic SCR conduction during overvoltage transients

Applications

Industrial PLC Backplane

Memory Address Buffering

Use Scenario: Isolating CPU address bus from multiple I/O module slots in modular programmable logic controllers.

IC Role / Device Role / Timing Role: Octal inverting buffer with dual enable - provides direction-controlled, noise-immune address latching per slot group.

Use Value: Prevents bus contention during hot-swap insertion; 24mA drive sustains signal integrity across 15cm backplane traces.

Use Scenario: Driving 8-bit address lines from a microcontroller to external SRAM or EPROM chips.

IC Role / Device Role / Timing Role: Inverting 3-state buffer - enables multiplexed access to shared memory space while minimizing propagation delay skew.

Use Value: 4.2ns typical tPD ensures setup/hold timing margins at 25MHz bus clock rates.

Automotive Body Control Module

Legacy Bus Interface Adapter

Use Scenario: Interfacing 5V CAN controller outputs to 3.3V microcontroller GPIOs in body electronics ECUs.

IC Role / Device Role / Timing Role: Level-shifting bus buffer - leverages wide VCC range (2–6V) and rail-to-rail input tolerance for mixed-voltage translation.

Use Value: Eliminates discrete level-shifters; –55°C to +125°C rating meets AEC-Q100 Grade 2 requirements.

Use Scenario: Adapting legacy ISA or PC/104 bus signals to modern FPGA-based carrier boards.

IC Role / Device Role / Timing Role: Pin-compatible replacement for 74LS240 - retains identical truth table and enable logic while improving speed and noise margin.

Use Value: Reduces board redesign effort; 28% VCC noise immunity suppresses interference from adjacent switching power supplies.

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal inverting 3-state buffer applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74AC240PWR	TSSOP-20, same AC/DC specs, TI's characterization tolerances differ slightly on VOH/VOL at 24mA load	Identical pinout and function - validated for TI-based reference designs	Preferred when sourcing from TI-authorized channels or requiring TI-specific qualification reports
74VHC240MTCX	VHC family: higher ICC (max 20µA), slower tPD (6.5ns typ), but superior 3.3V optimization	Better suited for low-voltage-only systems where 5V operation is unnecessary	Select when VCC ≤ 3.6V and lower dynamic power outweighs speed requirement

Compared with SN74AC240PWR and 74VHC240MTCX, the 74AC240TTR offers the fastest propagation delay (4.2ns) and lowest quiescent current (4µA) among TSSOP-packaged octal inverters, making it optimal for high-speed, low-power industrial bus isolation where timing margin and standby consumption are critical.

Availability

74AC240TTR is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive body control modules, memory address buffering, and legacy bus interface adapters requiring stable component supply and long-term lifecycle support.

Supply support for 74AC240TTR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The 74AC logic family targets high-speed, low-power, and high-noise-immunity applications in industrial control, instrumentation, and legacy system upgrades where reliability across extended temperature ranges is essential.

FAQ

Is the 74AC240TTR pin-compatible with standard 74-series 240 devices?

Yes - it is fully pin- and function-compatible with the 74LS240 and 74HC240, sharing identical TSSOP-20 pinout, truth table, and active-low 3-state enable logic. No PCB redesign is needed for drop-in replacement, though voltage and timing parameters differ per AC-family specifications.

What is the maximum capacitive load the 74AC240TTR can drive reliably?

The device is characterized for CL = 50pF in AC testing and guarantees 24mA output drive into 50Ω transmission lines. For lumped capacitive loads, reliable operation is confirmed up to 75pF per output (per manufacturer's application note AN2027), beyond which propagation delay increases and edge rate degrades.

Does the 74AC240TTR support partial power-down or I/O retention when VCC is off?

No - it lacks Ioff protection or power-down high-impedance mode. When VCC = 0V, all inputs and outputs become undefined and may draw leakage current. External isolation (e.g., series resistors or analog switches) is required for hot-insertion or multi-rail systems where VCC sequencing is uncontrolled.

Can the 74AC240TTR be used in 3.3V-only systems without level shifters?

Yes - its 2V to 6V operating range and rail-to-rail input voltage specification (VI = 0 to VCC) allow direct use with 3.3V supplies. VOH exceeds 3.0V and VOL stays below 0.5V at 24mA load, meeting 3.3V LVTTL and CMOS input thresholds without external components.

74AC240TTR Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: 74AC

Package/Case:: 20-TSSOP (0.173", 4.40mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Obsolete

Logic Type:: Buffer, Inverting

Number of Elements:: 2

Number of Bits per Element:: 4

Input Type:: -

Output Type:: 3-State

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

Voltage - Supply:: 2V ~ 6V

Operating Temperature:: -55°C ~ 125°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-TSSOP

74AC240TTR FAQ

1.How can I place an order for 74AC240TTR through Aetrix?

Please submit a Request for Quotation (RFQ) for 74AC240TTR 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 74AC240TTR reliable?

The price and inventory of 74AC240TTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74AC240TTR is usually 5 days.

3.What payment methods are accepted for 74AC240TTR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74AC240TTR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 74AC240TTR?

74AC240TTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 74AC240TTR 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 74AC240TTR?

For technical support, including 74AC240TTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74AC240TTR requirements.

6.How does Aetrix verify that 74AC240TTR is sourced from the original manufacturer or authorized distributors?

All 74AC240TTR 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 74AC240TTR meets industry standards.

7.What is the process for return or replacement of 74AC240TTR?

All 74AC240TTR units undergo pre-shipment inspection (PSI). If there is an issue with 74AC240TTR, 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 74AC240TTR part is unused and in its original packaging.

Return procedure for 74AC240TTR:

1.Submit a request within 90 days.

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

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