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onsemi 74LCXR2245SJX
- Part No.:
- 74LCXR2245SJX
- Manufacturer:
- onsemi
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
74LCXR2245SJX.pdf
- Description:
- IC TXRX NON-INVERT 3.6V 20SOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,983
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Product details
Overview
74LCXR2245SJX from Fairchild Semiconductor is a low-voltage, 8-bit bidirectional transceiver with 5V-tolerant I/O, 26Ω integrated series resistors on all A/B ports, 3.3V/2.5V VCC operation (2.3–3.6V), and 8.0ns max propagation delay at VCC = 3.3V. It enables level-shifting between 2.5V/3.3V buses and legacy 5V systems in memory expansion and peripheral interconnect applications.
For engineers reviewing the 74LCXR2245SJX datasheet, pinout, applications, or equivalent options, key selection criteria include 5V tolerance without external clamping, built-in 26Ω output impedance for EMI suppression, 3-STATE bidirectional control via OE/T/R, ±12mA drive at 3.0V, and live-insertion support during hot-swap operations.
Technical Context
The 74LCXR2245SJX implements dual-bus bidirectional data flow controlled by separate Transmit/Receive (T/R) and Output Enable (OE) inputs - T/R selects direction (A→B or B→A), while OE forces both ports into high-impedance state. Its advanced CMOS process delivers high-speed switching (tPHL/tPLH ≤ 8.0ns at 3.3V) with ultra-low ICC (≤10µA) in quiescent mode.
All I/O pins feature 5V tolerance across VCC = 2.3–3.6V, enabling safe interfacing to 5V logic without level translators. The integrated 26Ω series resistor per output reduces overshoot/undershoot and improves signal integrity on stubbed or unterminated traces - a design-critical feature for noise-sensitive industrial and telecom backplanes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2.3V–3.6V operating supply; supports mixed-voltage system integration with 2.5V/3.3V domains. |
| I/O Voltage Tolerance | 0V–5.5V input/output voltage range independent of VCC; eliminates need for external clamping diodes when interfacing to 5V buses. |
| Propagation Delay | Max 8.0ns (VCC = 3.3V, CL = 50pF); ensures timing compliance in high-speed parallel bus designs up to ~100MHz. |
| Output Drive | ±12mA at VCC = 3.0V; sufficient to drive standard TTL loads and moderate capacitive bus stubs without external buffers. |
| Series Resistance | 26Ω integrated on all A0–A7 and B0–B7 outputs; damps reflections and reduces EMI emissions without discrete resistors. |
| Power-Down Leakage | IOFF ≤ 10µA at VCC = 0V with VI/VO = 5.5V; prevents back-powering and maintains isolation during system sleep states. |
| ESD Rating | Human Body Model > 2000V; meets industrial handling requirements without additional protection circuitry. |
Pinout & Package
74LCXR2245SJX is packaged in a 20-lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm wide (Package Code M20D), with standard 1.27mm pitch and gull-wing leads. Pin 1 is marked by a notch or dot; device orientation follows JEDEC MO-150 mechanical standards.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OE) | Output Enable Input | Active-Low global enable: drives both A and B ports into high-impedance when HIGH; requires pull-up to VCC for power-up safety. |
| 2 (T/R) | Transmit/Receive Control | Determines data direction: LOW = B→A, HIGH = A→B; must be stable before OE activation to avoid bus contention. |
| 3–10 (A0–A7) | Side A Bidirectional I/O | 8-bit port with 5V-tolerant inputs/outputs and integrated 26Ω series resistance; connects to local low-voltage bus (e.g., 3.3V CPU address/data). |
| 11 (GND) | Ground Reference | Primary ground return for VCC and I/O; must be low-inductance connection to minimize ground bounce in high-speed switching. |
| 12–19 (B0–B7) | Side B Bidirectional I/O | 8-bit port identical to A-side; interfaces to external 5V subsystems (e.g., legacy peripherals, EEPROMs, or FPGAs) with no level-shifter required. |
| 20 (VCC) | Supply Voltage | 2.3–3.6V core supply; decoupling capacitor (0.1µF ceramic) required within 5mm of pin for AC noise suppression. |
Key Features
| Feature | Design Value |
|---|---|
| 5V-tolerant I/O architecture | Enables direct connection to 5V logic without external voltage translators or clamping diodes, reducing BOM count and PCB area. |
| Integrated 26Ω series termination | Reduces signal ringing and EMI emissions on both A and B ports, eliminating need for 16 discrete 26Ω resistors and associated layout complexity. |
| Live insertion/withdrawal support | High-impedance power-down state (OE = HIGH) prevents bus contention during hot-plug events in modular backplane or card-edge systems. |
| Low dynamic power dissipation | CPD = 25pF at 10MHz enables <1mW typical active power at 3.3V/10MHz, critical for thermally constrained embedded modules. |
| Robust latch-up immunity | Latch-up performance exceeds 500mA per IEC 61000-4-2, ensuring reliability in noisy industrial environments with transient coupling. |
Applications
| Memory Expansion Interface | Legacy Peripheral Bridge |
|---|---|
|
Use Scenario: Expanding SRAM or Flash capacity on a 3.3V microcontroller board requiring access to 5V-compatible memory devices. IC Role / Device Role / Timing Role: Bidirectional data transceiver translating between MCU's 3.3V data bus and 5V memory I/O, with direction controlled by address decode logic. Use Value: Eliminates external level shifters and discrete termination resistors, reducing component count by ≥18 parts and improving signal integrity on 8-bit parallel memory bus. |
Use Scenario: Connecting a modern 2.5V FPGA I/O bank to legacy 5V UART, SPI, or GPIO peripherals in industrial control panels. IC Role / Device Role / Timing Role: Voltage-tolerant bidirectional buffer managing data flow direction via FPGA-controlled T/R signal and enabling/disabling via OE during configuration phases. Use Value: Enables seamless interoperability without redesigning legacy peripheral boards or adding complex power-domain isolation circuitry. |
| Hot-Swappable Module Backplane | EMI-Sensitive Telecom Interface |
|
Use Scenario: Data routing between hot-pluggable daughter cards and a 3.3V motherboard in modular test equipment or base station subracks. IC Role / Device Role / Timing Role: Isolation transceiver placed at card edge; OE tied to presence-detect signal to force high-Z during insertion/removal. Use Value: Prevents bus contention and signal corruption during live card swaps, meeting NEBS Level 3 hot-swap compliance requirements. |
Use Scenario: Interfacing a 3.3V DSP to a 5V analog front-end ASIC in wireless infrastructure where radiated emissions must meet FCC Class B limits. IC Role / Device Role / Timing Role: Low-noise bidirectional data path with built-in 26Ω damping on all 16 lines, reducing spectral peaks at harmonics of clock frequency. Use Value: Cuts radiated EMI by ≥6dB compared to standard transceivers, avoiding costly ferrite beads or shielded cables in RF-dense enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 74LVC245APW,118 | No integrated series resistors; 5V-tolerant I/O only at VCC = 3.3V; tPD = 5.6ns (faster but less EMI robust). | Lacks built-in 26Ω termination; requires external resistors for EMI control in high-speed layouts. | Select when maximum speed is prioritized over EMI reduction and board space is available for discrete termination. |
| SN74AVC245DGVR | Supports 1.2V–3.6V VCC; 5V-tolerant only with external clamping; no integrated series resistors; higher drive (±24mA). | Requires external TVS diodes for 5V bus protection; lacks inherent signal damping capability. | Choose for ultra-low-voltage systems (<1.8V) where 74LCXR2245SJX's 2.3V minimum VCC is insufficient. |
Compared with 74LVC245APW,118 and SN74AVC245DGVR, the 74LCXR2245SJX uniquely combines 5V tolerance, integrated 26Ω termination, and live-insertion support in a single 20-pin SOP - delivering lower EMI, reduced BOM, and simplified layout for industrial and telecom backplane designs.
Availability
74LCXR2245SJX is available at Aetrix Electronics and suitable for memory expansion, legacy peripheral bridging, hot-swappable module backplanes, and EMI-sensitive telecom interfaces requiring stable component supply and long-term industrial availability.
Supply support for 74LCXR2245SJX 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, signal conditioning, and interface ICs before its acquisition by ON Semiconductor in 2016; its legacy logic portfolio remains widely deployed in industrial and telecom infrastructure.
The 74LCXR2245SJX belongs to Fairchild's LCX family of low-voltage, 5V-tolerant logic devices designed specifically for mixed-voltage system interfacing, EMI reduction, and hot-swap reliability in mission-critical embedded platforms.
FAQ
What is the minimum VCC required for reliable operation of the 74LCXR2245SJX?
The 74LCXR2245SJX specifies a minimum operating VCC of 2.3V across the full temperature range (–40°C to +85°C). Below 2.3V, parameters such as VOH, VOL, and tPD are not guaranteed - for example, at VCC = 2.0V, the device may power up but fail to meet 5V-tolerance or timing specs. Always operate the 74LCXR2245SJX within 2.3V–3.6V for full compliance with datasheet specifications.
Can the 74LCXR2245SJX safely interface a 3.3V microcontroller with a 5V EEPROM without external components?
Yes - the 74LCXR2245SJX supports 0V–5.5V input/output voltage levels regardless of VCC (2.3V–3.6V), enabling direct connection between a 3.3V MCU and 5V EEPROM. Its 5V-tolerant I/O eliminates clamping diodes, and the integrated 26Ω series resistors suppress ringing on SDA/SCL or data/address lines. No level translators, pull-ups, or termination resistors are needed for basic I²C or parallel EEPROM interfacing.
How does the 26Ω series resistor in the 74LCXR2245SJX improve signal integrity?
The 26Ω resistor integrated on each A/B port output acts as source termination, matching typical PCB trace impedances (40–70Ω) to reduce reflections at the driver end. This minimizes overshoot/undershoot (measured as ≤0.5V peak deviation in dynamic tests), lowers radiated EMI, and stabilizes eye diagrams in 8-bit parallel buses running up to 100MHz. Unlike discrete resistors, it is precisely matched across all 16 lines and immune to layout parasitics.
What is the recommended power-up sequence for the 74LCXR2245SJX to avoid bus contention?
To prevent contention during power-up, tie OE to VCC via a pull-up resistor (minimum value determined by driver current capability, typically 4.7kΩ–10kΩ) so the device powers up in high-impedance state. Ensure VCC stabilizes before asserting T/R or driving A/B bus signals. Do not float OE or T/R - unused inputs must be held HIGH or LOW per datasheet Note 4, as floating control lines can cause metastability and unintended data flow.
Is the 74LCXR2245SJX pin-compatible with other 20-pin transceivers like the 74LCX245?
No - the 74LCXR2245SJX has a distinct pinout optimized for bidirectional control: OE is on Pin 1, T/R on Pin 2, A0–A7 on Pins 3–10, GND on Pin 11, B0–B7 on Pins 12–19, and VCC on Pin 20. In contrast, the 74LCX245 places OE on Pin 19 and uses separate A/B enable pins. Swapping them causes immediate bus conflicts and potential damage; always verify pin mapping against the 74LCXR2245SJX datasheet Figure 1 before PCB layout.
74LCXR2245SJX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74LCXR
- Package/Case:
- 20-SOIC (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:
- 12mA, 12mA
- Voltage - Supply:
- 2V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOP
74LCXR2245SJX FAQ
1.How can I place an order for 74LCXR2245SJX through Aetrix?
Please submit a Request for Quotation (RFQ) for 74LCXR2245SJX 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 74LCXR2245SJX reliable?
The price and inventory of 74LCXR2245SJX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74LCXR2245SJX is usually 5 days.
3.What payment methods are accepted for 74LCXR2245SJX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74LCXR2245SJX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74LCXR2245SJX?
74LCXR2245SJX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74LCXR2245SJX 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 74LCXR2245SJX?
For technical support, including 74LCXR2245SJX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74LCXR2245SJX requirements.
6.How does Aetrix verify that 74LCXR2245SJX is sourced from the original manufacturer or authorized distributors?
All 74LCXR2245SJX 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 74LCXR2245SJX meets industry standards.
7.What is the process for return or replacement of 74LCXR2245SJX?
All 74LCXR2245SJX units undergo pre-shipment inspection (PSI). If there is an issue with 74LCXR2245SJX, 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 74LCXR2245SJX part is unused and in its original packaging.
Return procedure for 74LCXR2245SJX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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