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onsemi 74LCXH2245MSAX
- Part No.:
- 74LCXH2245MSAX
- Manufacturer:
- onsemi
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
74LCXH2245MSAX.pdf
- Description:
- IC TXRX NON-INVERT 3.6V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,985
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Product details
Overview
74LCXH2245MSAX from Fairchild Semiconductor is a low-voltage bidirectional transceiver with bushold inputs and integrated 26 Ω series resistors on B-side outputs, designed for 2.3–3.6 V bus interfacing between mixed-voltage domains. It features 8-bit non-inverting data flow control via T/R input, 3-STATE output enable (OE), 7.0 ns max propagation delay at 3.3 V, and ±12 mA B-port drive capability at 3.0 V - used in memory expansion, peripheral bridging, and FPGA I/O buffering.
For engineers reviewing the 74LCXH2245MSAX datasheet, pinout, applications, or equivalent options, key selection criteria include bushold-enabled floating-input immunity, B-port EMI-reducing series termination, 5 V-tolerant control inputs, and compatibility with 2.5 V/3.3 V system buses requiring direction-controlled bidirectional data transfer.
Technical Context
The 74LCXH2245MSAX implements a dual-bus bidirectional buffer architecture where data direction is controlled by the T/R signal, while OE independently places both A and B ports into high-impedance state. Its bushold circuitry actively maintains logic levels on unused inputs without external pull-ups, reducing board space and BOM count.
Each B-port output integrates a 26 Ω series resistor to suppress overshoot/undershoot during fast switching, improving signal integrity on stub-loaded or unterminated traces. The device operates across 2.3–3.6 V VCC, supports 5 V-tolerant OE and T/R inputs, and delivers <10 µA quiescent ICC at 3.3 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2.3 V to 3.6 V - enables interoperability between 2.5 V and 3.3 V logic domains without level shifters |
| tPD Max | 7.0 ns at VCC = 3.3 V - ensures sub-10 ns latency for high-speed bus arbitration and data handshaking |
| B-Port Output Drive | ±12 mA at VCC = 3.0 V - sustains robust signal integrity driving capacitive loads up to 50 pF |
| Bushold Input Current | Min 45 µA hold current at VIN = 0.7 V - eliminates need for external pull-up resistors on floating A/B inputs |
| Integrated Series Resistor | 26 Ω on all B-port outputs - reduces edge-induced EMI and ringing without discrete components |
| 5 V-Tolerant Inputs | OE and T/R accept 0–5.5 V - allows direct connection to legacy 5 V controllers without interface logic |
| ICC Quiescent | 10 µA max at VCC = 3.3 V - supports low-power standby modes in portable and battery-backed systems |
Pinout & Package
74LCXH2245MSAX is packaged in a 20-lead Shrink Small Outline Package (SSOP), JEDEC MO-150 compliant, 5.3 mm wide, with 0.65 mm lead pitch and exposed pad not present.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OE) | Output Enable Input | Active-low global 3-STATE control for both A and B ports - disables all I/Os simultaneously |
| 2 (T/R) | Transmit/Receive Control | Determines data direction: LOW = B→A, HIGH = A→B - enables dynamic bus arbitration |
| 3–10 (A0–A7) | Side A Bidirectional I/O | Non-inverting buffers with bushold - retain valid logic state when unconnected or floating |
| 11 (GND) | Ground Reference | Primary power return path for all internal logic and I/O circuits |
| 12–19 (B0–B7) | Side B Bidirectional I/O | Non-inverting buffers with bushold + integrated 26 Ω series resistor per output - reduces EMI on driven lines |
| 20 (VCC) | Supply Voltage | 2.3–3.6 V core supply - powers logic, bushold circuitry, and output drivers |
Key Features
| Feature | Design Value |
|---|---|
| Bushold Input Circuitry | Maintains stable logic levels on unconnected A/B pins without external pull resistors - reduces component count and layout complexity |
| 26 Ω Integrated Series Resistors (B Port) | Embedded termination minimizes signal reflections and overshoot on PCB traces - improves signal fidelity without discrete parts |
| 5 V-Tolerant Control Inputs | OE and T/R accept 0–5.5 V signals - enables direct interfacing with 5 V microcontrollers or FPGAs in mixed-voltage systems |
| Low-Voltage Operation (2.3–3.6 V) | Supports modern low-power SoC and FPGA I/O standards while maintaining backward compatibility with 3.3 V infrastructure |
| High-Speed Propagation (7.0 ns) | Enables real-time bidirectional data transfer in memory-mapped peripherals and high-bandwidth interconnects |
Applications
| Memory Expansion Interface | FPGA-to-Peripheral Bridge |
|---|---|
|
Use Scenario: Connecting a 3.3 V FPGA to legacy 2.5 V SRAM or Flash memory with shared address/data bus. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing direction-controlled data flow between mismatched voltage domains. Use Value: Eliminates need for discrete level shifters and pull-up networks while maintaining <7 ns timing margin for synchronous read/write cycles. |
Use Scenario: Interfacing a 2.5 V FPGA I/O bank to 3.3 V UART, SPI, or GPIO peripherals on an industrial control board. IC Role / Device Role / Timing Role: Voltage-aware bidirectional buffer enabling safe, glitch-free communication across voltage boundaries. Use Value: Bushold prevents floating inputs during FPGA configuration; B-port 26 Ω resistors suppress noise on long peripheral traces. |
| Hot-Swappable Module Interface | Low-Power Embedded Bus Arbitration |
|
Use Scenario: Backplane interface for hot-pluggable daughter cards operating at 2.5 V or 3.3 V in telecom line cards. IC Role / Device Role / Timing Role: Isolating and translating bidirectional control/data lines during insertion/removal sequences. Use Value: 3-STATE disable via OE prevents bus contention; 5 V-tolerant controls allow use of legacy hot-swap supervisors. |
Use Scenario: Shared I²C or SMBus data line between multiple 2.5 V sensors and a 3.3 V host MCU in battery-powered IoT node. IC Role / Device Role / Timing Role: Direction-aware repeater extending bus length and fan-out while preserving protocol timing. Use Value: Sub-10 µA quiescent current extends battery life; bushold avoids spurious interrupts from floating sensor lines. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 74LVC245ADTR2G | No bushold; no integrated series resistors; 1.65–3.6 V VCC; 5 V-tolerant inputs only on control pins | Lacks floating-input immunity and B-port EMI suppression - requires external pull-ups and termination | Preferred where cost sensitivity outweighs design simplification; suitable for fixed-configuration, low-noise environments |
| SN74AVC245DGVR | Higher speed (tPD = 3.2 ns); no bushold; no integrated resistors; 1.2–3.6 V VCC; auto-direction sensing option available | Requires external direction control or additional logic for T/R function; lacks passive input retention | Chosen for ultra-low-latency applications where active bus management justifies added complexity and component count |
Compared with 74LCXH2245MSAX, the 74LVC245ADTR2G offers broader VCC range but increases BOM and layout effort, while SN74AVC245DGVR delivers faster timing at the expense of bushold reliability and built-in termination - making 74LCXH2245MSAX optimal for robust, low-component-count 2.5/3.3 V bus interfaces.
Availability
74LCXH2245MSAX is available at Aetrix Electronics and suitable for memory expansion, FPGA peripheral bridging, and hot-swappable module interfaces requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature and voltage ranges.
Supply support for 74LCXH2245MSAX 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
Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and logic ICs before its acquisition by ON Semiconductor in 2016; its legacy logic portfolio remains widely deployed in industrial and communications infrastructure.
The 74LCXH2245MSAX belongs to Fairchild's LCXH family of low-voltage, high-speed CMOS transceivers engineered for mixed-voltage bus interfacing in space-constrained, noise-sensitive embedded systems.
FAQ
What is the function of the bushold circuitry in the 74LCXH2245MSAX?
The bushold circuitry in the 74LCXH2245MSAX actively maintains the last valid logic state on any floating A or B input pin, eliminating the need for external pull-up or pull-down resistors. This feature reduces BOM cost and PCB area while preventing undefined states during power-up, hot-swap events, or unconnected test points. The 74LCXH2245MSAX specifies minimum hold current of 45 µA at VIN = 0.7 V, ensuring reliable operation across its full 2.3–3.6 V VCC range.
Does the 74LCXH2245MSAX support 5 V logic inputs?
Yes, the 74LCXH2245MSAX has 5 V-tolerant OE and T/R control inputs, accepting voltages from 0 V to 5.5 V regardless of VCC level. This allows direct interfacing with legacy 5 V microcontrollers or FPGAs without level-shifting circuitry. However, the A and B data I/O pins are not 5 V-tolerant and must operate within the 2.3–3.6 V VCC-referenced voltage range. The 74LCXH2245MSAX datasheet confirms this distinction in the DC Electrical Characteristics table.
What is the purpose of the 26 Ω series resistors on the B outputs of the 74LCXH2245MSAX?
The 26 Ω series resistors integrated into each B-port output of the 74LCXH2245MSAX serve to dampen signal edge ringing and reduce overshoot/undershoot on PCB traces, particularly in unterminated or stub-loaded bus configurations. This built-in termination improves signal integrity and EMI performance without requiring discrete resistors. The 74LCXH2245MSAX specification explicitly states "Equivalent 26 Ω series resistor on B Port outputs" in its Features section.
Can the 74LCXH2245MSAX be used in hot-swap applications?
Yes, the 74LCXH2245MSAX supports hot-swap operation through three key features: 3-STATE outputs controllable via OE, bushold on all I/Os to prevent floating states during insertion, and power-down high-impedance behavior. When OE is held HIGH, both A and B ports enter high-Z mode, avoiding bus contention. The 74LCXH2245MSAX also exhibits latch-up immunity exceeding 500 mA, enhancing robustness during transient fault conditions common in hot-plug scenarios.
What package type does the 74LCXH2245MSAX use?
The 74LCXH2245MSAX uses a 20-lead Shrink Small Outline Package (SSOP), JEDEC MO-150 compliant, with 5.3 mm body width and 0.65 mm lead pitch. This package is designated as MSA20 in Fairchild's ordering nomenclature and is distinct from SOIC (M20B), SOP (M20D), and TSSOP (MTC20) variants. The SSOP footprint provides higher pin density than SOIC while maintaining surface-mount compatibility and thermal performance suitable for industrial ambient temperatures.
74LCXH2245MSAX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74LCXH
- Package/Case:
- 20-SSOP (0.209", 5.30mm 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; 12mA, 12mA
- Voltage - Supply:
- 2V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
74LCXH2245MSAX FAQ
1.How can I place an order for 74LCXH2245MSAX through Aetrix?
Please submit a Request for Quotation (RFQ) for 74LCXH2245MSAX 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 74LCXH2245MSAX reliable?
The price and inventory of 74LCXH2245MSAX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74LCXH2245MSAX is usually 5 days.
3.What payment methods are accepted for 74LCXH2245MSAX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74LCXH2245MSAX transactions.
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4.How is shipping managed for 74LCXH2245MSAX?
74LCXH2245MSAX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74LCXH2245MSAX 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 74LCXH2245MSAX?
For technical support, including 74LCXH2245MSAX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74LCXH2245MSAX requirements.
6.How does Aetrix verify that 74LCXH2245MSAX is sourced from the original manufacturer or authorized distributors?
All 74LCXH2245MSAX 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 74LCXH2245MSAX meets industry standards.
7.What is the process for return or replacement of 74LCXH2245MSAX?
All 74LCXH2245MSAX units undergo pre-shipment inspection (PSI). If there is an issue with 74LCXH2245MSAX, 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 74LCXH2245MSAX part is unused and in its original packaging.
Return procedure for 74LCXH2245MSAX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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