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onsemi 74LCX240SJ
- Part No.:
- 74LCX240SJ
- Manufacturer:
- onsemi
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
74LCX240SJ.pdf
- Description:
- IC BUFFER INVERT 3.6V 20SOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,618
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Product details
Overview
74LCX240SJ from onsemi is an inverting octal buffer/line driver with 3-state outputs, designed for memory address driving, clock distribution, and bus-oriented transmitter/receiver roles in mixed-voltage systems. It operates from 1.65 V to 5.5 V VCC, tolerates 5 V inputs/outputs, delivers ±24 mA drive at 3.0 V, and achieves 6.5 ns max propagation delay at 3.3 V - enabling use in 3.3 V logic interfacing with legacy 5 V buses.
For engineers reviewing the 74LCX240SJ datasheet, pinout, applications, or equivalent options, key selection criteria include 5 V-tolerant I/O compatibility, low-power CMOS operation, high-speed 3-state control timing (tPZH/tPHZ ≤ 8.0 ns at 3.3 V), and SOIC-20W package suitability for industrial PCB layouts requiring thermal reliability and live insertion support.
Technical Context
The 74LCX240SJ implements dual independent 3-state enable controls (OE1, OE2) for four-channel groups, supporting flexible bus partitioning. Its advanced CMOS process enables rail-to-rail 5 V-tolerant I/O while maintaining sub-10 ns AC performance across 1.65–5.5 V supply range.
It features power-down high-impedance inputs/outputs, proprietary noise/EMI reduction circuitry, and latch-up immunity exceeding 100 mA - critical for robust operation in electrically noisy industrial backplanes and hot-swap applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 1.65 V to 5.5 V - supports direct interface between 1.8 V, 2.5 V, 3.3 V, and 5 V logic domains without level shifters. |
| tPD Max | 6.5 ns at VCC = 3.3 V - ensures sub-7 ns signal propagation for high-speed address/data buffering in memory subsystems. |
| Output Drive | ±24 mA at VCC = 3.0 V - drives standard TTL loads and multiple CMOS inputs without external buffers. |
| I/O Voltage Tolerance | −0.5 V to +6.5 V - withstands 5 V signals safely while powered from 3.3 V or lower, eliminating risk of damage during mixed-voltage transitions. |
| 3-State Enable Timing | tPZH/tPHZ ≤ 8.0 ns at VCC = 3.3 V - enables fast bus arbitration and clean signal isolation in time-critical control paths. |
| ESD Rating | Human Body Model >2000 V - provides baseline ESD robustness for handling and assembly in non-classified environments. |
| Thermal Resistance θJA | 96 °C/W (SOIC-20W) - supports continuous operation up to +125 °C ambient in thermally constrained enclosures. |
Pinout & Package
74LCX240SJ is packaged in SOIC-20W (Case 751BJ), a 300-mil wide-body surface-mount package with 1.27 mm pitch, JEDEC MS-013 compliant, rated MSL Level 3, and suitable for reflow soldering per J-STD-020.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | OE1, OE2 | Independent 3-state enable inputs for two 4-bit groups - allows selective activation of I0–I3/O0–O3 (OE1) and I4–I7/O4–O7 (OE2). |
| 2–9 | I0–I7 | Inverting input terminals - each drives corresponding output with polarity inversion; all tolerate 0–5.5 V regardless of VCC. |
| 11–18 | O0–O7 | Inverting 3-state outputs - high-impedance when OE1/OE2 = HIGH; sink/source ±24 mA when active at 3.0 V. |
| 10 | GND | Ground reference for all internal circuitry and I/O - must be low-inductance connection to minimize ground bounce. |
| 20 | VCC | Primary power supply - supplies core logic and I/O drivers; decoupling capacitor (0.1 µF) required within 5 mm. |
Key Features
| Feature | Design Value |
|---|---|
| 5 V tolerant I/O | Enables direct connection to 5 V buses while operating from 1.65–3.3 V supplies - eliminates external level translators in mixed-voltage designs. |
| Live insertion support | Power-down high-impedance I/O state prevents bus contention during hot-plug events - essential for modular backplane and field-replaceable unit applications. |
| Low dynamic power | CPD = 25 pF at 3.3 V - reduces switching current consumption in high-frequency clock/address buffering, extending system-level power budget. |
| Noise/EMI reduction | Proprietary output slew-rate control minimizes simultaneous switching noise - improves signal integrity on dense PCBs with shared power/ground planes. |
| Latch-up immunity | Exceeds 100 mA per JEDEC JESD78 - ensures robust operation under transient overvoltage or ground-bounce conditions in industrial environments. |
Applications
| Memory Address Buffering | Industrial Bus Transceiver |
|---|---|
|
Use Scenario: Driving 16-bit address lines from a 3.3 V microcontroller to a 5 V SRAM or EPROM bank in programmable logic controllers. IC Role / Device Role / Timing Role: Inverting octal buffer with 5 V-tolerant outputs - translates low-voltage address signals while maintaining timing integrity and bus loading margin. Use Value: Eliminates need for discrete level-shifting components, reduces BOM count by one IC, and maintains <6.5 ns propagation delay for synchronous memory access timing. |
Use Scenario: Isolating and driving CAN or RS-485 transceiver control lines in factory automation gateways where 3.3 V MCU interfaces with 5 V physical layer ICs. IC Role / Device Role / Timing Role: 3-state line driver with independent OE controls - enables bidirectional bus management and prevents signal contention during protocol handshaking. Use Value: ±24 mA drive strength ensures reliable logic-level assertion across long traces; tPZH ≤ 8.0 ns supports sub-100 ns control response for real-time bus arbitration. |
| Hot-Swappable Module Interface | Legacy System Upgrade Bridge |
|
Use Scenario: Providing configurable 3-state isolation between a mainboard's 3.3 V data bus and plug-in I/O modules in test equipment racks. IC Role / Device Role / Timing Role: Dual-enable octal buffer - allows independent enable/disable of upper/lower byte lanes during module insertion/removal. Use Value: Power-down high-impedance I/O prevents backfeeding or short-circuits during live insertion; MSL Level 3 rating supports standard moisture-sensitive handling protocols. |
Use Scenario: Replacing obsolete 74F240 in aging telecom shelf controllers where 5 V TTL logic must interoperate with newly added 3.3 V FPGA peripherals. IC Role / Device Role / Timing Role: Pin-compatible drop-in replacement with identical SOIC-20 footprint - retains existing PCB layout while reducing power and improving noise immunity. Use Value: 6.5 ns tPD matches or exceeds 74F240 speed; 10 µA ICC max at 3.3 V cuts quiescent power by >90% versus F-series equivalents. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 74LVC240APW | Same 1.65–5.5 V VCC, but only 5 V-tolerant inputs (not outputs); tPD = 5.2 ns @ 3.3 V; TSSOP-20 only. | Requires external clamping or series resistors if driving 5 V loads; unsuitable for true 5 V bus driving without redesign. | Select when output voltage swing is limited to VCC and board space favors TSSOP; avoid when 5 V output drive is mandatory. |
| SN74LVCH240A | Higher drive (±32 mA @ 3.3 V); supports 1.65–3.6 V only; no 5 V output tolerance; includes bus-hold on inputs. | Cannot interface directly with 5 V buses; requires level-shifting for legacy system integration; bus-hold eliminates need for pull-ups on unused inputs. | Prefer for new 3.3 V-only designs needing stronger drive and input stabilization; not viable for mixed-voltage upgrades. |
Compared with 74LVC240APW and SN74LVCH240A, the 74LCX240SJ uniquely combines full 5 V I/O tolerance, SOIC-20W thermal performance (96 °C/W), and proven live-insertion capability - making it the only option among the three qualified for retrofitting industrial backplanes with zero layout change.
Availability
74LCX240SJ is available at Aetrix Electronics and suitable for industrial control systems, legacy system upgrades, and hot-swappable module interfaces requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant manufacturing.
Supply support for 74LCX240SJ 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient silicon solutions for automotive, industrial, cloud, medical, and IoT applications.
The LCX logic family - including the 74LCX240SJ - was engineered for low-voltage, high-speed interoperability between 1.8 V–5 V systems, targeting memory expansion, bus bridging, and mixed-signal interface consolidation in space- and power-constrained equipment.
FAQ
What is the maximum operating temperature for the 74LCX240SJ?
The 74LCX240SJ is rated for continuous operation from −40 °C to +125 °C ambient temperature. Its SOIC-20W package has a thermal resistance (θJA) of 96 °C/W, enabling reliable performance in sealed industrial enclosures without forced airflow - provided PCB copper area and decoupling meet onsemi's layout guidelines in the 74LCX240/D datasheet.
Does the 74LCX240SJ support true 5 V output drive while powered from 3.3 V?
Yes - the 74LCX240SJ guarantees 5 V-tolerant outputs, meaning it can safely drive and sustain 5 V logic levels on O0–O7 even when VCC = 3.3 V. This is confirmed in the Absolute Maximum Ratings (VO = −0.5 to +6.5 V in Tri-State Mode) and DC Electrical Characteristics (VOH ≥ VCC − 0.1 V, with VI up to 5.5 V), making the 74LCX240SJ suitable for direct interfacing with 5 V TTL loads.
How does the 74LCX240SJ handle unused inputs?
Per the Recommended Operating Conditions section of the 74LCX240/D datasheet, all unused inputs on the 74LCX240SJ must be tied to a defined logic level - either GND or VCC. Leaving inputs floating risks increased ICC, noise susceptibility, and potential oscillation due to CMOS input stage metastability. The 74LCX240SJ does not include internal bus-hold circuitry, so external termination is mandatory for unconnected pins.
Can the 74LCX240SJ be used in hot-swap applications?
Yes - the 74LCX240SJ explicitly supports live insertion/withdrawal, as stated in its Features list. Its power-down high-impedance inputs and outputs prevent bus contention during power sequencing. To ensure safe operation, OE should be tied to VCC via a pull-up resistor (minimum value determined by driver sourcing capability), per Note 1 in the datasheet - a requirement validated in the 74LCX240SJ's design for industrial backplane modules.
What is the typical capacitive load drive capability of the 74LCX240SJ?
The 74LCX240SJ is characterized for CL = 50 pF in dynamic switching tests (e.g., VOLP/VOLV measurements), and its output capacitance (COUT) is specified at 8 pF typical. With ±24 mA drive at 3.0 V, it reliably drives standard 50 pF loads across PCB traces and multiple CMOS inputs. For heavier loads (>75 pF), propagation delay increases - consult Figure 4 waveforms and AC Electrical Characteristics table in the 74LCX240/D datasheet for derating guidance specific to the 74LCX240SJ.
74LCX240SJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74LCX
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- 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
74LCX240SJ FAQ
1.How can I place an order for 74LCX240SJ through Aetrix?
Please submit a Request for Quotation (RFQ) for 74LCX240SJ 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 74LCX240SJ reliable?
The price and inventory of 74LCX240SJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74LCX240SJ is usually 5 days.
3.What payment methods are accepted for 74LCX240SJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74LCX240SJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74LCX240SJ?
74LCX240SJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74LCX240SJ 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 74LCX240SJ?
For technical support, including 74LCX240SJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74LCX240SJ requirements.
6.How does Aetrix verify that 74LCX240SJ is sourced from the original manufacturer or authorized distributors?
All 74LCX240SJ 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 74LCX240SJ meets industry standards.
7.What is the process for return or replacement of 74LCX240SJ?
All 74LCX240SJ units undergo pre-shipment inspection (PSI). If there is an issue with 74LCX240SJ, 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 74LCX240SJ part is unused and in its original packaging.
Return procedure for 74LCX240SJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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