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onsemi 74LCX240SJX
- Part No.:
- 74LCX240SJX
- Manufacturer:
- onsemi
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
74LCX240SJX.pdf
- Description:
- IC BUFFER INVERT 3.6V 20SOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,000
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Product details
Overview
74LCX240SJX from Fairchild Semiconductor is an inverting octal buffer/line driver designed for low-voltage (2.3V–3.6V) bus interface applications with 5V-tolerant I/O, 6.5ns max propagation delay at VCC = 3.3V, ±24mA output drive at 3.0V, and power-down high-impedance support-used in memory address buffering and clock distribution across mixed-voltage systems.
For engineers reviewing the 74LCX240SJX datasheet, pinout, applications, or equivalent options, this device is selected for 3.3V logic interfacing to legacy 5V buses, requiring verified 3-STATE timing, input/output voltage tolerance, and ESD robustness (>2000V HBM) without level-shifting circuitry.
Technical Context
The 74LCX240SJX implements dual independent 3-STATE enable controls (OE1, OE2), each gating four inverting outputs (O0–O3 and O4–O7), supporting live insertion via high-impedance power-up/down behavior when OE is pulled up. Its advanced CMOS process enables 2.3V–3.6V operation while maintaining TTL-compatible thresholds and 5V-safe I/O clamping.
Propagation delay skew is specified at ≤1.0ns between any two outputs switching in the same direction, and dynamic noise suppression circuitry reduces simultaneous switching noise-critical for stable data/address bus driving in dense PCB layouts with shared VCC/GND planes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2.3V–3.6V operating supply; supports 2.5V and 3.3V system rails with guaranteed performance. |
| tPD Max | 6.5ns at VCC = 3.3V, CL = 50pF; enables reliable timing in high-speed address/data bus applications up to ~100MHz. |
| IOL / IOH | ±24mA at VCC = 3.0V; drives standard TTL loads or multiple CMOS inputs without external buffers. |
| VI / VO Tolerance | –0.5V to +7.0V DC input/output voltage range; allows direct connection to 5V signals without damage or level shifters. |
| ICC Max | 10µA quiescent current at VCC = 3.3V; minimizes standby power in battery-backed or low-power embedded systems. |
| ESD HBM | >2000V human body model; provides robust handling during board assembly and field service. |
| Output Skew | ≤1.0ns (tOSHL/tOSLH); ensures deterministic timing alignment across all eight outputs in synchronous bus environments. |
Pinout & Package
74LCX240SJX is housed in a 20-lead Small Outline Package (SOP), EIAJ TYPE II, 5.3mm wide (Package Code M20D), with gull-wing leads and JEDEC-compliant footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 4, 6, 10, 11, 13, 15 | Inverting Input (I0–I7) | Eight buffered inputs; each inverted and driven to corresponding output; tolerate 0–5.5V regardless of VCC. |
| 3, 5, 7, 9 | OE2 (3-STATE Enable) | Active-low enable for outputs O4–O7; must be pulled high via resistor during power transition to ensure Hi-Z state. |
| 12, 14, 16, 18 | OE1 (3-STATE Enable) | Active-low enable for outputs O0–O3; independently controlled from OE2 for flexible bus partitioning. |
| 8, 17 | GND | Ground reference pins; both required for proper noise immunity and thermal dissipation in SOP package. |
| 20 | VCC | Primary power supply (2.3V–3.6V); decoupling capacitor (0.1µF) recommended adjacent to this pin. |
| 19, 16, 15, 13, 11, 9, 7, 5 | Outputs (O0–O7) | Inverting buffered outputs; each capable of ±24mA sink/source at 3.0V; enter high-impedance when respective OE is HIGH. |
Key Features
| Feature | Design Value |
|---|---|
| 5V-tolerant I/O | Enables direct interfacing between 3.3V logic domains and legacy 5V peripherals without external translators. |
| Independent dual OE control | Allows selective enabling of two 4-bit output groups (O0–O3 and O4–O7), supporting segmented bus arbitration or partial shutdown. |
| Live insertion support | Guaranteed high-impedance I/O during power-up/down when OE is externally pulled high-prevents bus contention on hot-plug systems. |
| Low dynamic noise | Proprietary EMI reduction circuitry limits ground bounce and crosstalk during simultaneous output switching. |
| Latch-up immunity | Exceeds 500mA per JEDEC JESD78, ensuring robust operation under transient overvoltage or ESD stress events. |
Applications
| Memory Address Buffering | PCI Bus Interface |
|---|---|
|
Use Scenario: Driving 32-bit address lines from a 3.3V microcontroller to a 5V SRAM or EPROM bank. IC Role / Device Role / Timing Role: Inverting octal buffer providing level-shifted, high-drive address signal conditioning with precise 3-STATE timing control. Use Value: Eliminates need for discrete level shifters while maintaining <6.5ns propagation delay and sub-1ns output skew across all address bits. |
Use Scenario: Interfacing a 3.3V PCI controller to legacy 5V PCI add-in cards in industrial backplane systems. IC Role / Device Role / Timing Role: Bidirectional bus transceiver buffer with 5V-tolerant I/O and independent OE control for direction management. Use Value: Supports hot-plug compliance via power-down Hi-Z mode and withstands PCI bus voltage excursions up to 5.5V without damage. |
| Embedded Clock Distribution | Industrial Control Backplane |
|
Use Scenario: Distributing a 3.3V system clock to multiple 5V peripheral ICs (e.g., UARTs, ADCs) in a programmable logic controller. IC Role / Device Role / Timing Role: Low-skew inverting clock driver with matched propagation delay across all eight outputs. Use Value: Ensures <1.0ns inter-output skew and maintains signal integrity at clock frequencies up to 100MHz in noisy factory environments. |
Use Scenario: Isolating and strengthening digital I/O signals between a 3.3V FPGA and 5V relay drivers or sensor interfaces on a DIN-rail mounted PLC module. IC Role / Device Role / Timing Role: Robust octal line driver with ±24mA drive strength and >2000V HBM ESD protection for harsh industrial wiring. Use Value: Reduces external protection components and improves long-term reliability against field-induced transients and contact ESD. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 74LVC240APW,118 | 3.3V-only I/O tolerance (0–3.6V), no 5V tolerance; lower ICC (5µA), identical 6.2ns tPD at 3.3V. | Suitable only in fully 3.3V systems; cannot interface directly to 5V buses without external protection. | Select when full 5V tolerance is unnecessary and lowest static power is prioritized. |
| SN74LVCH240APWR | 3.3V VCC with 5V-tolerant I/O like 74LCX240SJX; higher drive (+32mA/–32mA at 3.3V), but larger TSSOP-20 package (4.4mm). | Better drive capability for heavy capacitive loads; requires different land pattern than SOP-20. | Choose when higher output current or TI's enhanced latch-up immunity (600mA) is required. |
Compared with 74LVC240APW,118 and SN74LVCH240APWR, the 74LCX240SJX uniquely balances 5V tolerance, SOP-20 footprint compatibility, and proven live-insertion behavior-making it optimal for retrofitting legacy 5V systems with modern low-voltage controllers.
Availability
74LCX240SJX is available at Aetrix Electronics and suitable for memory address buffering, PCI bus interface, embedded clock distribution, and industrial control backplane applications requiring stable component supply and long-term obsolescence mitigation.
Supply support for 74LCX240SJX 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 analog and mixed-signal ICs, acquired by ON Semiconductor in 2016; its legacy logic portfolio remains widely deployed in industrial and telecom infrastructure.
The 74LCX240SJX belongs to the LCX low-voltage CMOS logic family, engineered for mixed-voltage system interoperability-specifically targeting 3.3V/2.5V logic interfacing with 5V legacy buses in computing, networking, and automation equipment.
FAQ
What is the maximum supply voltage rating for the 74LCX240SJX?
The 74LCX240SJX has an absolute maximum VCC rating of +7.0V, but its recommended operating range is strictly 2.3V to 3.6V. Operation outside this range may cause functional failure or accelerated wear-even if within absolute limits-so designs must regulate VCC to 3.3V ±0.3V for guaranteed AC/DC performance per the datasheet.
Does the 74LCX240SJX support true bidirectional data flow?
No, the 74LCX240SJX is an inverting unidirectional octal buffer-not a transceiver. It accepts inputs (I0–I7), inverts them, and drives corresponding outputs (O0–O7). Direction is fixed; bidirectional operation requires external control logic or a separate transceiver IC such as the 74LCX245.
How should OE pins be handled during power-up to avoid bus contention with the 74LCX240SJX?
To ensure high-impedance outputs during power-up/down, OE1 and OE2 must be tied to VCC through pull-up resistors. The minimum resistance value depends on the driver's sourcing capability; Fairchild specifies this is necessary to guarantee Hi-Z state before VCC stabilizes-failure to do so risks output contention on shared buses.
Can the 74LCX240SJX drive standard TTL loads directly?
Yes-the 74LCX240SJX delivers ±24mA output current at VCC = 3.0V, exceeding the ±0.4mA/±16mA requirements of standard TTL inputs. This allows direct fan-out to up to 10+ TTL loads without external buffers, provided VCC is ≥2.7V and layout minimizes trace inductance.
Is the 74LCX240SJX pin-compatible with other 20-pin octal buffers like the 74HC240?
No-while both are 20-pin octal buffers, the 74LCX240SJX uses a distinct pinout: OE1 and OE2 are split across pins 12/14/16/18 and 3/5/7/9, unlike the single OE pin of 74HC240. PCB layout and schematic symbols must match the M20D SOP footprint and LCX-specific terminal mapping-not HC-family conventions.
74LCX240SJX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74LCX
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- 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 ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOP
74LCX240SJX FAQ
1.How can I place an order for 74LCX240SJX through Aetrix?
Please submit a Request for Quotation (RFQ) for 74LCX240SJX 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 74LCX240SJX reliable?
The price and inventory of 74LCX240SJX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74LCX240SJX is usually 5 days.
3.What payment methods are accepted for 74LCX240SJX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74LCX240SJX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74LCX240SJX?
74LCX240SJX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74LCX240SJX 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 74LCX240SJX?
For technical support, including 74LCX240SJX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74LCX240SJX requirements.
6.How does Aetrix verify that 74LCX240SJX is sourced from the original manufacturer or authorized distributors?
All 74LCX240SJX 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 74LCX240SJX meets industry standards.
7.What is the process for return or replacement of 74LCX240SJX?
All 74LCX240SJX units undergo pre-shipment inspection (PSI). If there is an issue with 74LCX240SJX, 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 74LCX240SJX part is unused and in its original packaging.
Return procedure for 74LCX240SJX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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