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Texas Instruments CD74HCT240EE4
- Part No.:
- CD74HCT240EE4
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
CD74HCT240EE4.pdf
- Description:
- 8-CH, 4.5-V TO 5.5-V INVERTERS W
- Quantity:
- Payment:
- Shipping:
Inventory:2,214
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Product details
Overview
CD74HCT240EE4 from Texas Instruments is an inverting octal buffer/line driver with three-state outputs and dual active-low output enables, designed for bidirectional bus interfacing in 5-V TTL-compatible digital systems. It delivers 8ns typical propagation delay at VCC = 5 V, CL = 15 pF, supports ±25 mA output drive per pin, operates across –55°C to +125°C, and features buffered inputs for noise immunity.
For engineers reviewing the CD74HCT240EE4 datasheet, CD74HCT240EE4 pinout, CD74HCT240EE4 application, or CD74HCT240EE4 equivalent, this device is selected for high-reliability bus buffering where logic inversion, output enable control, LSTTL compatibility, and wide temperature operation are required - especially in industrial control backplanes and legacy system upgrades.
Technical Context
The CD74HCT240EE4 implements eight independent inverting buffer channels, each with a dedicated output enable (OE) input shared across two groups (1OE for Y1–Y4, 2OE for Y5–Y8). Its HCT logic family ensures direct compatibility with LSTTL input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V) while maintaining CMOS power efficiency.
All channels feature three-state outputs with high-impedance disable states controlled by active-low OE signals, enabling bus sharing without contention. Input buffering provides consistent switching behavior and reduces sensitivity to slow-rising/falling edges, supporting reliable operation up to 100 MHz under typical load conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Type | Inverting octal buffer with three-state outputs - performs signal inversion and bus isolation simultaneously. |
| Supply Voltage | 4.5 V to 5.5 V - matches standard 5-V TTL systems without level-shifting circuitry. |
| Propagation Delay | 9 ns typical (tPLH/tPHL) at VCC = 4.5 V, CL = 50 pF - enables timing-critical data path buffering in high-speed control logic. |
| Output Drive | ±25 mA per output - sufficient to directly drive 15 LSTTL loads or terminate short PCB traces. |
| Operating Temperature | –55°C to +125°C - qualified for extended industrial, automotive under-hood, and aerospace environments. |
| Input Compatibility | LSTTL and CMOS - accepts standard TTL logic levels while drawing ≤1 μA input current at VOH/VOL. |
| Three-State Leakage | ±5 μA max (–55°C to +125°C) - ensures minimal bus leakage during high-Z state in multi-driver configurations. |
Pinout & Package
CD74HCT240EE4 is supplied in a 20-pin PDIP (Plastic Dual In-line Package) with 25.40 mm × 6.35 mm body size and through-hole mounting. Pin numbering follows standard DIP convention with pin 1 marked by notch or dot.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | Inputs A1–A8 | Active-high logic inputs; inverted and gated before appearing on corresponding outputs. |
| 9, 10 | Output Enables 1OE, 2OE | Active-low enables controlling Y1–Y4 (pin 9) and Y5–Y8 (pin 10); both must be low for output assertion. |
| 11, 13, 14, 15, 16, 17, 18, 20 | Outputs Y1–Y8 | Inverted outputs; high-impedance when respective OE is high - enables shared-bus arbitration. |
| 12, 19 | GND, VCC | Power reference (pin 12) and supply (pin 19); decoupling capacitor placement near pin 19 is critical for noise suppression. |
Key Features
| Feature | Design Value |
|---|---|
| Inverting three-state buffers | Provides logic inversion plus bus contention avoidance via high-Z output control - eliminates need for external inverters and direction-control logic. |
| Dual active-low output enables | Allows independent control of two 4-bit output groups (Y1–Y4 and Y5–Y8), enabling partial bus activation or staggered enable sequencing. |
| High-current bus driver outputs | Delivers ±25 mA per output to directly interface with legacy TTL loads or drive moderate-capacitance PCB traces without external drivers. |
| Buffered inputs | Reduces sensitivity to input rise/fall time variations and improves noise margin - critical for reliable operation in electrically noisy industrial environments. |
| Wide temperature range | Rated for –55°C to +125°C operation - suitable for unheated outdoor enclosures, engine control units, and military-grade subsystems. |
Applications
| Industrial Backplane Interface | Legacy System Bus Expansion |
|---|---|
|
Use Scenario: Interfacing microcontroller I/O ports to a 16-bit parallel backplane carrying address/data/control signals in programmable logic controllers. IC Role / Device Role / Timing Role: Inverting buffer isolating MCU outputs from backplane capacitance while enabling/disabling segments via 1OE/2OE. Use Value: Prevents signal contention during hot-swap events and maintains timing integrity with 9 ns propagation delay across full temperature range. |
Use Scenario: Adding peripheral slots to a vintage 8-bit computer architecture using 5-V TTL signaling standards. IC Role / Device Role / Timing Role: Level-translating and buffering expansion bus signals between CPU and add-on cards requiring inverted control strobes. Use Value: Direct LSTTL compatibility eliminates discrete resistor networks; three-state outputs allow dynamic slot arbitration without hardware redesign. |
| Automotive Sensor Data Aggregation | Test Equipment Signal Conditioning |
|
Use Scenario: Consolidating analog-to-digital converter outputs from multiple engine sensors onto a shared diagnostic bus in ECU modules. IC Role / Device Role / Timing Role: Inverting and gating sensor data streams before multiplexing onto CAN controller input lines. Use Value: –55°C to +125°C rating ensures reliability under hood; ±25 mA drive handles long trace runs to remote connectors. |
Use Scenario: Isolating and conditioning digital stimulus signals in automated test equipment where multiple instruments share a common timing bus. IC Role / Device Role / Timing Role: Providing clean, inverted, three-state-controlled signal paths between pattern generators and DUT interfaces. Use Value: Low 5 μA max three-state leakage prevents crosstalk between inactive channels during parallel test execution. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT240N | Identical logic function, pinout, and electrical specs; same PDIP-20 package but TI's newer commercial-grade variant. | Qualified for 0°C to +70°C only - not suitable for extended temperature deployments. | Select SN74HCT240N only for cost-sensitive commercial designs where full –55°C to +125°C range is unnecessary. |
| 74HCT240D | Same functionality in SOIC-20 package (12.80 mm × 7.50 mm); identical AC/DC specs but different thermal resistance (RθJA = 109.1°C/W vs. 84.6°C/W for PDIP). | Requires surface-mount assembly and offers smaller footprint - unsuitable for through-hole prototyping or legacy repair. | Choose 74HCT240D when board space is constrained and reflow capability exists; verify thermal derating for high-power-density layouts. |
Compared with SN74HCT240N and 74HCT240D, CD74HCT240EE4 uniquely combines military-grade temperature qualification, through-hole manufacturability, and proven field reliability in harsh-environment control systems - making it the preferred choice where long-term operational stability is non-negotiable.
Availability
CD74HCT240EE4 is available at Aetrix Electronics and suitable for industrial automation, automotive ECU design, and test equipment development requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for CD74HCT240EE4 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
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The CD74HCT240EE4 belongs to TI's CD74HCT high-speed CMOS logic family, engineered for robust 5-V TTL-compatible interfacing in mission-critical systems demanding wide temperature operation and bus contention control.
FAQ
What is the logic function of CD74HCT240EE4?
The CD74HCT240EE4 is an inverting octal buffer with three-state outputs and dual active-low output enables (1OE and 2OE). Each of its eight inputs (A1–A8) drives a corresponding inverted output (Y1–Y8), which enters high-impedance state when either 1OE or 2OE is high. This allows bidirectional bus control without external direction logic.
Does CD74HCT240EE4 support 3.3-V input signals?
No - CD74HCT240EE4 is an HCT-family device designed for 4.5 V to 5.5 V supply operation and LSTTL-compatible inputs (VIL ≤ 0.8 V, VIH ≥ 2.0 V). Applying 3.3-V logic signals may result in undefined output states; use level-shifting circuitry or a 74LVC-series buffer for mixed-voltage interfacing.
What is the maximum output current per pin for CD74HCT240EE4?
CD74HCT240EE4 supports ±25 mA DC output current per pin under recommended operating conditions. This rating applies to both sourcing (VOH) and sinking (VOL) modes at VCC = 4.5 V to 5.5 V and ambient temperatures from –55°C to +125°C, enabling direct drive of 15 LSTTL loads.
Can CD74HCT240EE4 be used in place of CD74HC240E?
CD74HCT240EE4 and CD74HC240E share identical pinout and logic function but differ in voltage compatibility: CD74HCT240EE4 requires 4.5–5.5 V and accepts LSTTL inputs, whereas CD74HC240E operates from 2–6 V and uses CMOS input thresholds. Substitution is only valid if the system uses 5-V supply and TTL-level signals.
What decoupling capacitor value is recommended for CD74HCT240EE4?
A 0.1-μF ceramic capacitor is recommended between VCC (pin 19) and GND (pin 12) for CD74HCT240EE4, placed as close as possible to the package. For improved high-frequency noise rejection, TI recommends paralleling with a 1-μF capacitor - especially in systems with fast-switching adjacent logic or switching power supplies.
CD74HCT240EE4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- 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:
- 6mA, 6mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
CD74HCT240EE4 FAQ
1.How can I place an order for CD74HCT240EE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HCT240EE4 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 CD74HCT240EE4 reliable?
The price and inventory of CD74HCT240EE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HCT240EE4 is usually 5 days.
3.What payment methods are accepted for CD74HCT240EE4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HCT240EE4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HCT240EE4?
CD74HCT240EE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HCT240EE4 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 CD74HCT240EE4?
For technical support, including CD74HCT240EE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HCT240EE4 requirements.
6.How does Aetrix verify that CD74HCT240EE4 is sourced from the original manufacturer or authorized distributors?
All CD74HCT240EE4 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 CD74HCT240EE4 meets industry standards.
7.What is the process for return or replacement of CD74HCT240EE4?
All CD74HCT240EE4 units undergo pre-shipment inspection (PSI). If there is an issue with CD74HCT240EE4, 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 CD74HCT240EE4 part is unused and in its original packaging.
Return procedure for CD74HCT240EE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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