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

onsemi 74VCX245BQX

Name: 74VCX245BQX
Brand: onsemi
SKU: 74VCX245BQX
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 74VCX245BQX

Manufacturer:: onsemi

Category:: Buffers, Drivers, Receivers, Transceivers

Package:: 20-WFQFN Exposed Pad

Datasheet:: 74VCX245BQX.pdf

Description:: IC TXRX NON-INVERT 3.6V 20DQFN

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Product details

Overview

74VCX245BQX from ON Semiconductor is a low-voltage bidirectional transceiver with 3.6V-tolerant I/O, designed for bus interface applications between mixed-voltage domains. It operates from 1.4V to 3.6V V_CC, delivers ±24 mA drive at 3.0V, features 3.5 ns max propagation delay (V_CC = 3.3V), and uses a Pb-free 20-terminal DQFN package (2.5 × 4.5 mm).

For engineers reviewing the 74VCX245BQX datasheet, pinout, applications, or equivalent options, key selection criteria include bidirectional data flow control via T/R input, 3-STATE output enable/disable timing (t_PZL/t_PLZ ≤ 4.5 ns), power-off high-impedance behavior, and compatibility with 1.4–3.6V logic systems requiring level translation.

Technical Context

The 74VCX245BQX implements eight non-inverting bidirectional buffers with independent direction control (T/R) and 3-STATE output enable (OE). Its CMOS architecture supports live insertion/withdrawal and maintains high-impedance I/O during power-off states, enabling hot-swap capability in backplane and modular systems.

It achieves voltage-level interoperability by accepting inputs up to 3.6V while operating on V_CC as low as 1.4V - critical for interfacing legacy 3.3V peripherals with modern 1.8V or 2.5V SoCs. Propagation skew (≤0.75 ns) and tight AC timing ensure signal integrity across all eight channels under varying load conditions (CL = 15–30 pF).

Key Specifications

Parameter	Value and Actual Design Meaning
V_CC Range	1.4V to 3.6V - enables direct integration into mixed-supply systems without external level shifters
I/O Voltage Tolerance	Up to 3.6V - allows safe connection to 3.3V buses while powered from 1.8V or 2.5V rails
t_PHL/t_PLH Max	3.5 ns @ V_CC = 3.3V, CL = 30 pF - supports >200 MHz bus toggle rates in high-speed interconnects
I_OH/I_OL	±24 mA @ V_CC = 3.0V - drives 10+ LVTTL loads or 50 Ω transmission lines with minimal signal degradation
Power-Off High-Z	IO_OFFI ≤ 10 µA @ (VI, VO) = 0–3.6V - prevents back-driving and bus contention when V_CC = 0V
ESD Rating	HBM ≥ 2000V - meets industrial-grade robustness requirements for board-level handling and field operation
Package	DQFN-20 (MLP020B), 2.5 × 4.5 mm - ultra-thin, leadless footprint ideal for space-constrained portable and embedded designs

Pinout & Package

Pb-Free 20-terminal Depopulated Quad Very-Thin Flat Pack No Leads (DQFN), JEDEC MO-241 compliant, 2.5 mm × 4.5 mm body, 0.5 mm pitch, exposed die attach pad (DAP) for thermal enhancement.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3, 4, 5, 6, 7, 8	Side A I/O (A0–A7)	Bidirectional data terminals for port A; high-impedance when OE = HIGH or during power-off
9	GND	Ground reference for V_CC and signal return path
10, 11, 12, 13, 14, 15, 16, 17	Side B I/O (B0–B7)	Bidirectional data terminals for port B; electrically identical to A-side with same voltage tolerance
18	V_CC	Primary supply rail (1.4–3.6V); powers internal logic and output drivers
19	OE	Active-LOW output enable - disables both ports simultaneously into high-impedance state
20	T/R	Transmit/Receive control - determines data flow direction (A→B or B→A)
DAP (bottom center)	Die Attach Pad	Thermally conductive, electrically isolated copper pad; must be soldered to PCB ground plane for optimal thermal performance

Key Features

Feature	Design Value
Live Insertion Support	Power-off high-impedance I/O and controlled enable/disable timing allow safe hot-plug operation in modular backplanes
Low-Voltage Interoperability	Operates down to 1.4V V_CC while tolerating 3.6V signals - eliminates need for discrete level translators in mixed-voltage subsystems
High-Speed Bus Interface	3.5 ns max propagation delay at 3.3V enables use in DDR memory buffers, FPGA I/O expansion, and high-throughput peripheral interfaces
Robust ESD Protection	2000V HBM rating ensures reliability during manufacturing, assembly, and field service without additional protection circuitry
Ultra-Compact Packaging	2.5 × 4.5 mm DQFN footprint reduces PCB area by >50% vs. SOIC-20, supporting miniaturized IoT and wearable electronics

Applications

Industrial PLC Backplane Interface	FPGA I/O Expansion Module
Use Scenario: Connecting multiple I/O modules to a central controller over a shared 3.3V backplane while the controller operates at 1.8V. IC Role / Device Role / Timing Role: Bidirectional voltage-translating transceiver managing data flow direction and bus isolation via OE and T/R control signals. Use Value: Eliminates external level-shifting components and reduces BOM count by integrating 3.6V-tolerant I/O with sub-2V core logic compatibility.	Use Scenario: Extending FPGA GPIO count to interface with legacy 3.3V peripherals (e.g., ADCs, DACs, sensors) in battery-powered edge devices. IC Role / Device Role / Timing Role: Low-latency, low-power bidirectional buffer enabling synchronous data exchange between FPGA fabric and external devices. Use Value: Achieves <3.5 ns propagation delay and ±24 mA drive strength while consuming <20 µA quiescent current - critical for energy-efficient real-time sensing.
Embedded Memory Subsystem	Hot-Swappable Compute Card
Use Scenario: Isolating DDR SDRAM address/control lines between a 2.5V SoC and 3.3V memory module in an automotive infotainment head unit. IC Role / Device Role / Timing Role: Direction-controlled bus transceiver synchronizing address/command transfers with precise t_PZL/t_PLZ timing (≤4.5 ns). Use Value: Maintains signal integrity across voltage domains while meeting DDR timing budgets and supporting JEDEC-compliant DQFN thermal performance.	Use Scenario: Enabling hot-swap capability in modular server blades where compute cards are inserted/removed without powering down the chassis backplane. IC Role / Device Role / Timing Role: Power-off high-impedance I/O and live-insertion support prevent bus contention and back-driving during card insertion/removal events. Use Value: IO_OFFI ≤ 10 µA ensures zero leakage current when unpowered, satisfying MIL-STD-1399 and IEC 61000-4-2 system-level hot-swap compliance.

Industrial PLC Backplane Interface

FPGA I/O Expansion Module

Use Scenario: Connecting multiple I/O modules to a central controller over a shared 3.3V backplane while the controller operates at 1.8V.

IC Role / Device Role / Timing Role: Bidirectional voltage-translating transceiver managing data flow direction and bus isolation via OE and T/R control signals.

Use Value: Eliminates external level-shifting components and reduces BOM count by integrating 3.6V-tolerant I/O with sub-2V core logic compatibility.

Use Scenario: Extending FPGA GPIO count to interface with legacy 3.3V peripherals (e.g., ADCs, DACs, sensors) in battery-powered edge devices.

IC Role / Device Role / Timing Role: Low-latency, low-power bidirectional buffer enabling synchronous data exchange between FPGA fabric and external devices.

Use Value: Achieves <3.5 ns propagation delay and ±24 mA drive strength while consuming <20 µA quiescent current - critical for energy-efficient real-time sensing.

Embedded Memory Subsystem

Hot-Swappable Compute Card

Use Scenario: Isolating DDR SDRAM address/control lines between a 2.5V SoC and 3.3V memory module in an automotive infotainment head unit.

IC Role / Device Role / Timing Role: Direction-controlled bus transceiver synchronizing address/command transfers with precise t_PZL/t_PLZ timing (≤4.5 ns).

Use Value: Maintains signal integrity across voltage domains while meeting DDR timing budgets and supporting JEDEC-compliant DQFN thermal performance.

Use Scenario: Enabling hot-swap capability in modular server blades where compute cards are inserted/removed without powering down the chassis backplane.

IC Role / Device Role / Timing Role: Power-off high-impedance I/O and live-insertion support prevent bus contention and back-driving during card insertion/removal events.

Use Value: IO_OFFI ≤ 10 µA ensures zero leakage current when unpowered, satisfying MIL-STD-1399 and IEC 61000-4-2 system-level hot-swap compliance.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74LVC245AQPWRQ1	Automotive-grade (AEC-Q100), wider V_CC range (1.65–3.6V), slightly higher t_PHL (4.2 ns @ 2.5V)	Qualified for automotive under-hood environments; not required for commercial industrial use	Select for automotive applications requiring qualification; otherwise 74VCX245BQX offers lower propagation delay at 1.8V–2.5V operation
74ALVC245PW,118	Smaller TSSOP-20 package (4.4 mm wide), identical electrical specs but no DQFN option	Lacks DQFN thermal and space advantages; suitable only where leaded packages are preferred for rework or prototyping	Choose when manual soldering or test probing is needed; 74VCX245BQX preferred for production-scale miniaturized designs

Compared with SN74LVC245AQPWRQ1 and 74ALVC245PW,118, the 74VCX245BQX provides superior speed at low V_CC (1.4–2.3V), optimized DQFN thermal performance, and broader industrial temperature support (−40°C to +85°C), making it ideal for compact, high-density embedded systems where timing margin and board space are critical.

Availability

74VCX245BQX is available at Aetrix Electronics and suitable for industrial PLC backplanes, FPGA I/O expansion modules, embedded memory subsystems, and hot-swappable compute cards requiring stable component supply, long-term lifecycle support, and consistent DQFN packaging.

Supply support for 74VCX245BQX 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

ON Semiconductor (formerly Fairchild Semiconductor) is a global semiconductor manufacturer specializing in power management, analog, sensor, and logic solutions for automotive, industrial, cloud computing, and consumer markets.

The 74VCX family was developed to deliver high-speed, low-voltage bidirectional logic with enhanced I/O tolerance and power-off safety - targeting next-generation embedded systems requiring compact, robust, and interoperable interface ICs.

FAQ

What is the minimum V_CC required for reliable operation of the 74VCX245BQX?

The 74VCX245BQX is fully specified to operate down to 1.4V V_CC. At this voltage, it supports 6 mA drive strength (I_OL/I_OH) and maintains valid logic thresholds (V_IL = 0.35×V_CC, V_IH = 0.65×V_CC). Below 1.4V, functionality is not guaranteed per datasheet specifications, and timing parameters such as t_PHL degrade significantly. The 74VCX245BQX remains functional across its full −40°C to +85°C temperature range at 1.4V.

Does the 74VCX245BQX support hot-swap operation, and what design considerations apply?

Yes, the 74VCX245BQX supports live insertion and withdrawal per datasheet Note 1. Its power-off high-impedance I/O (IO_OFFI ≤ 10 µA) prevents back-driving during unpowered states. To ensure robust hot-swap behavior, OE must be tied to V_CC via a pull-up resistor (value determined by driver sourcing capability), and unused bus terminals in HIGH-Z state must be held HIGH or LOW per Note 4. These measures guarantee clean bus isolation during card insertion/removal in systems like modular servers or industrial backplanes using the 74VCX245BQX.

How does the 74VCX245BQX handle voltage-level translation between 1.8V and 3.3V domains?

The 74VCX245BQX performs bidirectional level translation without external components: when powered at 1.8V V_CC, its inputs accept up to 3.6V signals (including 3.3V), and its outputs drive to valid 1.8V logic levels (VOH ≥ 1.25V, VOL ≤ 0.3V at I_OL = 6 mA). Conversely, with 3.3V V_CC, it interfaces natively with 3.3V peripherals while maintaining compatibility with 1.4–3.6V supplies. This makes the 74VCX245BQX ideal for bridging FPGA I/O banks, microcontroller buses, and legacy peripherals in mixed-voltage embedded systems.

What is the role of the DAP (Die Attach Pad) on the 74VCX245BQX DQFN package?

The DAP on the 74VCX245BQX is an exposed copper thermal pad located on the bottom center of the DQFN package. It is electrically isolated but thermally conductive, and must be soldered to a PCB copper pour connected to GND for effective heat dissipation. Per datasheet Figure 10, proper DAP soldering reduces junction-to-board thermal resistance by up to 40%, enabling sustained ±24 mA output drive at elevated ambient temperatures. Failure to connect the DAP may cause thermal throttling or reduced reliability in continuous high-current operation of the 74VCX245BQX.

Can the 74VCX245BQX replace the 74LVC245 in existing designs, and what layout changes are needed?

The 74VCX245BQX is not a drop-in replacement for the 74LVC245 due to package and pinout differences: the 74VCX245BQX uses a 20-pin DQFN (MLP020B) with 0.5 mm pitch and exposed DAP, whereas standard 74LVC245 variants use SOIC-20 or TSSOP-20. Electrical compatibility exists (same logic function, similar V_CC range, and I/O tolerance), but PCB redesign is required to accommodate the DQFN footprint, stencil aperture, and thermal pad layout. For pin-compatible alternatives, consider the 74VCX245MTC (TSSOP-20) variant of the same family instead of the 74VCX245BQX.

74VCX245BQX Specifications

Product attributes: Attribute value

Manufacturer:: onsemi

Series:: 74VCX

Package/Case:: 20-WFQFN Exposed Pad

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:: 1.4V ~ 3.6V

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-DQFN (2.5x4.5)

74VCX245BQX FAQ

1.How can I place an order for 74VCX245BQX through Aetrix?

Please submit a Request for Quotation (RFQ) for 74VCX245BQX 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 74VCX245BQX reliable?

The price and inventory of 74VCX245BQX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74VCX245BQX is usually 5 days.

3.What payment methods are accepted for 74VCX245BQX?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74VCX245BQX transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 74VCX245BQX?

74VCX245BQX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 74VCX245BQX 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 74VCX245BQX?

For technical support, including 74VCX245BQX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74VCX245BQX requirements.

6.How does Aetrix verify that 74VCX245BQX is sourced from the original manufacturer or authorized distributors?

All 74VCX245BQX 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 74VCX245BQX meets industry standards.

7.What is the process for return or replacement of 74VCX245BQX?

All 74VCX245BQX units undergo pre-shipment inspection (PSI). If there is an issue with 74VCX245BQX, 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 74VCX245BQX part is unused and in its original packaging.

Return procedure for 74VCX245BQX:

1.Submit a request within 90 days.

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

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