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

STMicroelectronics 74AC245TTR

Name: 74AC245TTR
Brand: STMicroelectronics
SKU: 74AC245TTR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 74AC245TTR

Manufacturer:: STMicroelectronics

Category:: Buffers, Drivers, Receivers, Transceivers

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

Datasheet:: 74AC245TTR.pdf

Description:: IC TXRX NON-INVERT 6V 20TSSOP

Quantity:: RFQ Add To RFQ list

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Inventory:1,431

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Product details

Overview

74AC245TTR from STMicroelectronics is an advanced high-speed CMOS octal bus transceiver with 3-state non-inverting outputs, used for bidirectional asynchronous data bus communication. It features 4.5ns typical propagation delay at 5V, ±24mA symmetrical output drive, 2V–6V operating voltage, and pin/function compatibility with standard 74-series 244 devices in TSSOP-20 package.

For engineers reviewing the 74AC245TTR datasheet, 74AC245TTR pinout, 74AC245TTR application, or 74AC245TTR equivalent, key selection criteria include direction-controlled bidirectional data flow, 50Ω transmission line driving capability, high noise immunity (28% VCC), and latch-up robustness in industrial bus interface designs.

Technical Context

The device implements a dual-bus architecture with DIR input controlling data flow direction between A- and B-side 8-bit ports, while G enables/disables all outputs into high-impedance state. Its sub-micron C2MOS process ensures low ICC (4µA max) and balanced tPLH/tPHL delays.

Input thresholds are rail-proportional (VIH = 2.1V min at VCC = 3V; VIL = 0.9V max), and outputs guarantee VOL ≤ 0.5V at 24mA sink and VOH ≥ 3.7V at 24mA source under 4.5V supply - enabling reliable interfacing across mixed-voltage systems.

Key Specifications

Parameter	Value and Actual Design Meaning
VCC Range	2V to 6V - supports mixed-voltage board-level interfacing (e.g., 3.3V logic to 5V peripherals)
tPD (Typ.)	4.5ns at VCC = 5V - enables >100MHz bus toggle rates in synchronous systems
IOL / IOH	24mA min - drives 50Ω transmission lines directly without external buffers
VNIH / VNIL	28% VCC min - rejects >1.4V noise on 5V buses, improving signal integrity
ICC (Max)	4µA at TA = 25°C - suitable for low-power standby modes in battery-backed systems
CIN / CI/O	5pF / 10pF - minimizes capacitive loading on high-speed address/data buses

Pinout & Package

TSSOP-20 package: 6.5mm × 4.4mm body, 0.65mm pitch, exposed pad not present, JEDEC MO-153 compliant.

Pin/Terminal	Circuit Role	Design Meaning
1	DIR	Direction control: LOW = A→B, HIGH = B→A; determines real-time data path polarity
2–9	A1–A8	Port A I/O: bidirectional data terminals tied to local bus or microcontroller data port
11–18	B1–B8	Port B I/O: bidirectional data terminals connected to peripheral or memory bus
19	G	Output enable: LOW = active drive, HIGH = 3-state isolation of both ports
10	GND	Ground reference for all I/O and internal logic
20	VCC	Positive supply: powers internal logic and output drivers; decoupling required per 74AC family practice

Key Features

Feature	Design Value
Symmetrical output drive	\|IOH\| = IOL = 24mA min - eliminates skew between rising/falling edges on shared bus lines
50Ω transmission line drive	Guaranteed incident-wave switching on 50Ω traces - reduces need for external termination resistors
High noise immunity	VNIH/VNIL = 28% VCC min - suppresses EMI-induced glitches in noisy industrial environments
Latch-up immunity	Improved vs. standard 74HC/74LS - withstands transient overvoltage without destructive latch-up

Applications

Industrial PLC Backplane Interface

Legacy ISA Bus Extension

Use Scenario: Isolating CPU data bus from modular I/O expansion slots in programmable logic controllers.

IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing data flow between x86-compatible controller and field I/O modules.

Use Value: 4.5ns tPD and 24mA drive ensure deterministic timing across 10-slot backplanes with stub lengths up to 15cm.

Use Scenario: Extending legacy ISA bus signals between motherboard and add-on cards in test instrumentation.

IC Role / Device Role / Timing Role: Level-shifting and bus-driving transceiver bridging 5V ISA bus to 3.3V FPGA-based peripherals.

Use Value: 2V–6V VCC range and rail-proportional inputs allow direct connection without level translators.

Automotive Diagnostic Interface

Embedded Data Acquisition Hub

Use Scenario: Interfacing OBD-II diagnostic port (SAE J1850) to microcontroller UART via parallel-to-serial conversion logic.

IC Role / Device Role / Timing Role: Direction-controlled data buffer isolating noisy vehicle CAN/LIN domains from sensitive MCU GPIO banks.

Use Value: 28% VCC noise margin prevents false reads during engine cranking transients (±100mV ripple).

Use Scenario: Aggregating sensor data from multiple ADCs and SPI peripherals onto a single microcontroller data bus.

IC Role / Device Role / Timing Role: Octal 3-state transceiver enabling time-multiplexed access to shared memory-mapped registers.

Use Value: Low 4µA ICC supports >10-year battery life in remote environmental monitoring nodes.

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal bus transceiver applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
74LVC245A	Lower VCC range (1.65–3.6V); 3.3V-only optimized; 26mA drive; 3.5ns tPD	Not suitable for 5V systems; requires level translation when interfacing to 5V peripherals	Select when full system operates at 3.3V and lowest possible power is critical
SN74ACT245	Same VCC range (4.5–5.5V only); higher drive (32mA); tighter AC specs; no -55°C rating	Limited to 5V-only designs; lacks wide temperature support for automotive under-hood use	Select for high-speed 5V-only backplanes where 32mA drive improves margin on long traces

Compared with 74LVC245A and SN74ACT245, the 74AC245TTR uniquely balances 2–6V operation, industrial temperature range (-55°C to +125°C), and proven latch-up immunity - making it optimal for mixed-voltage, mission-critical embedded interfaces.

Availability

74AC245TTR is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive diagnostic interfaces, legacy bus extensions, and embedded data acquisition hubs requiring stable component supply across extended temperature and voltage ranges.

Supply support for 74AC245TTR 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, 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 robust bus interface applications - emphasizing noise immunity, wide supply range, and reliability in harsh environments.

FAQ

What is the maximum clock frequency supported by 74AC245TTR in bus applications?

The 74AC245TTR does not operate on a clock; it is an asynchronous transceiver. Its 4.5ns typical propagation delay enables reliable data transfer at bus toggle rates exceeding 100MHz, provided setup/hold times of connected devices are met and trace impedance is controlled to 50Ω.

Can 74AC245TTR safely interface 3.3V and 5V logic domains without level shifters?

Yes - its 2V–6V VCC range, rail-proportional input thresholds (VIH = 2.1V min at 3V, 3.15V min at 4.5V), and 5.5V-tolerant inputs allow direct connection between 3.3V and 5V systems when powered at 5V, with no external level translation required.

Is the TSSOP-20 package of 74AC245TTR RoHS-compliant and lead-free?

Yes - STMicroelectronics' 74AC245TTR in TSSOP-20 packaging conforms to RoHS Directive 2011/65/EU and is manufactured with lead-free terminations and halogen-free molding compound, verified per ST's official product change notices and material declarations.

How does the DIR and G pin interaction affect bus isolation behavior?

When G = HIGH, both A and B ports enter high-impedance state regardless of DIR value - fully isolating the buses. When G = LOW, DIR selects direction: DIR = LOW enables A→B flow; DIR = HIGH enables B→A flow. This two-level control prevents bus contention during state transitions.

74AC245TTR 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:: Transceiver, Non-Inverting

Number of Elements:: 1

Number of Bits per Element:: 8

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

74AC245TTR FAQ

1.How can I place an order for 74AC245TTR through Aetrix?

Please submit a Request for Quotation (RFQ) for 74AC245TTR 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 74AC245TTR reliable?

The price and inventory of 74AC245TTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74AC245TTR is usually 5 days.

3.What payment methods are accepted for 74AC245TTR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74AC245TTR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 74AC245TTR?

74AC245TTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 74AC245TTR 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 74AC245TTR?

For technical support, including 74AC245TTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74AC245TTR requirements.

6.How does Aetrix verify that 74AC245TTR is sourced from the original manufacturer or authorized distributors?

All 74AC245TTR 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 74AC245TTR meets industry standards.

7.What is the process for return or replacement of 74AC245TTR?

All 74AC245TTR units undergo pre-shipment inspection (PSI). If there is an issue with 74AC245TTR, 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 74AC245TTR part is unused and in its original packaging.

Return procedure for 74AC245TTR:

1.Submit a request within 90 days.

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

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