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Texas Instruments CD74ACT240E
- Part No.:
- CD74ACT240E
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
CD74ACT240E.pdf
- Description:
- IC BUFF INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:130
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Product details
Overview
CD74ACT240E from Texas Instruments is an octal 3-state buffer/line driver IC with active-low dual output enables, designed for bidirectional bus interfacing in industrial and embedded systems. It delivers ±24mA output drive, operates at 4.5V–5.5V, features balanced propagation delays (tPLH/tPHL ≤ 8.6ns @ 5V), and drives 50Ω transmission lines - enabling reliable signal integrity in high-speed digital backplanes and memory address/data buses.
For engineers reviewing the CD74ACT240E datasheet, CD74ACT240E pinout, CD74ACT240E application, or CD74ACT240E equivalent, key selection criteria include its TTL-compatible input thresholds (VIH = 2.0V, VIL = 0.8V), 3-state leakage current (±5μA max), thermal resistance (RθJA = 40°C/W in PDIP), and compatibility with FAST-family fanout requirements (drives 15 FAST ICs).
Technical Context
The CD74ACT240E implements two independent 4-bit banks (Bank 1: pins 2,4,6,8 → 12,14,16,18; Bank 2: pins 11,13,15,17 → 3,5,7,9), each controlled by dedicated active-low output enables (1OE on pin 1, 2OE on pin 19). Its RCA Advanced CMOS process ensures SCR latch-up resistance and operation across −40°C to +85°C.
It supports true 3-state bus contention management via simultaneous enable/disable of both banks, with output disable times (tPLZ/tPHZ) ≤ 13.4ns and enable times (tPZL/tPZH) ≤ 13.4ns at 5V - critical for glitch-free bus arbitration in microcontroller peripheral interfaces and FPGA I/O expansion.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5V–5.5V - ensures compatibility with 5V TTL logic domains and stable operation under industrial rail tolerances. |
| Output Drive | ±24mA - sufficient to directly drive 50Ω transmission lines or fan out to 15 FAST ICs without external buffers. |
| Propagation Delay | ≤8.6ns (tPLH/tPHL, VCC=5V) - enables reliable timing in 100+ MHz address/data bus applications. |
| Input Thresholds | VIH = 2.0V, VIL = 0.8V - provides robust noise immunity (30% of VCC) and seamless interface with TTL and CMOS sources. |
| 3-State Leakage | ±5μA max (TA = −40°C to +85°C) - minimizes bus leakage current during high-impedance state, preserving signal integrity. |
| Quiescent Current | 80μA max (TA = −40°C to +85°C) - supports low-static-power system design in always-on control modules. |
| Thermal Resistance | RθJA = 40°C/W (PDIP-20 package) - allows sustained operation at full drive strength without heatsinking in ambient ≤70°C. |
Pinout & Package
CD74ACT240E is supplied in a 20-pin plastic dual in-line package (PDIP, N suffix), body size 24.33mm × 6.35mm, with through-hole mounting and industry-standard 0.3" width.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (1OE) | Active-low bank 1 output enable | Asserting low enables outputs Y0–Y3 (pins 12,14,16,18); high places them in high-impedance state. |
| 2,4,6,8 (1A0–1A3) | Bank 1 data inputs | Accept TTL/CMOS logic levels; drive corresponding outputs when 1OE is low. |
| 12,14,16,18 (1Y0–1Y3) | Bank 1 buffered outputs | Inverting outputs (Y = A) - match standard 74-series logic polarity for drop-in replacement. |
| 11,13,15,17 (2A0–2A3) | Bank 2 data inputs | Independent 4-bit input path; synchronized with 2OE (pin 19) for dual-bank control. |
| 3,5,7,9 (2Y3–2Y0) | Bank 2 buffered outputs | Non-inverting outputs (Y = A); pin order reversed vs. standard layout to support PCB routing efficiency. |
| 19 (2OE) | Active-low bank 2 output enable | Enables/disables outputs Y0–Y3 of bank 2 independently - essential for time-multiplexed bus sharing. |
| 10 (GND), 20 (VCC) | Power terminals | Requires local 0.1μF ceramic bypass capacitor per supply pin to suppress switching noise and ensure stable operation. |
Key Features
| Feature | Design Value |
|---|---|
| SCR latch-up resistant CMOS process | Guarantees immunity to destructive latch-up events in noisy industrial environments with transient voltage spikes. |
| Balanced tPLH/tPHL propagation delays | Ensures symmetrical rise/fall timing across all 8 channels - critical for skew-sensitive parallel bus timing budgets. |
| 50Ω transmission line drive capability | Validated at +85°C - enables direct connection to controlled-impedance PCB traces without series termination resistors. |
| TTL-compatible input thresholds | VIH = 2.0V / VIL = 0.8V at VCC = 5V - eliminates need for level-shifting when interfacing with legacy 5V microcontrollers. |
| Low 3-state leakage (±5μA) | Prevents unintended bus loading during high-Z state - maintains signal integrity in multi-driver shared-bus architectures. |
Applications
| Industrial PLC Backplane Interface | Microcontroller I/O Expansion |
|---|---|
Use Scenario: Interfacing a 16-bit microcontroller's address/data bus to multiple peripheral modules on a DIN-rail mounted PLC backplane. IC Role / Device Role / Timing Role: Bidirectional 3-state buffer isolating CPU bus segments; enables time-multiplexed access to ADC, DAC, and relay driver modules. Use Value: ±24mA drive and 8.6ns propagation delay ensure clean signal edges across 15cm backplane traces at 20MHz bus clock rates. |
Use Scenario: Expanding GPIO count of an ARM Cortex-M4 MCU to drive 8-channel LED indicators and pushbutton inputs in a medical device HMI. IC Role / Device Role / Timing Role: Unidirectional level-shifting buffer translating 3.3V MCU outputs to 5V LED drivers while providing ESD-protected inputs for buttons. Use Value: TTL-compatible inputs accept direct 3.3V logic; 50Ω drive capability eliminates external current-limiting resistors for LEDs. |
| FPGA Peripheral Interface | Legacy Memory Address Buffering |
Use Scenario: Connecting a Xilinx Artix-7 FPGA's general-purpose I/O bank to external SPI flash, UART transceivers, and I²C sensors operating at 5V. IC Role / Device Role / Timing Role: Voltage-level translator and bus isolator; separates FPGA core logic (3.3V) from 5V peripherals using independent bank enables. Use Value: Dual active-low OE pins allow precise timing control of peripheral access windows, preventing bus contention during configuration sequences. |
Use Scenario: Buffering 20-bit address lines from a Z80 CPU to multiple 64KB SRAM chips in a retro-computing restoration project. IC Role / Device Role / Timing Role: High-speed address latch driver with low propagation skew - ensures simultaneous chip-select assertion across memory bank. Use Value: Balanced tPLH/tPHL < 9ns and RθJA = 40°C/W permit continuous operation at full speed without thermal throttling in enclosed enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal 3-state buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT240N | Identical electrical specs and pinout; manufactured by TI with identical AC/ACT family characterization and qualification. | No functional difference; same industrial temperature range (−40°C to +85°C) and PDIP packaging. | Select SN74ACT240N when requiring TI's current production part number with updated traceability and RoHS compliance documentation. |
| 74ACT240PC | Same logic function and pinout; fabricated by ON Semiconductor with minor variations in VIH/VIL tolerance (2.1V/0.9V vs. 2.0V/0.8V) and slightly higher ICC (100μA max). | Suitable for commercial-temperature (0°C to +70°C) applications only; not rated for industrial ambient extremes. | Choose 74ACT240PC only for cost-sensitive, non-industrial designs where extended temperature operation is unnecessary. |
Compared with SN74ACT240N and 74ACT240PC, CD74ACT240E offers identical performance and industrial-grade reliability but with legacy TI part numbering and long-established supply chain availability - making it preferred for legacy system repair and BOM continuity in deployed equipment.
Availability
CD74ACT240E is available at Aetrix Electronics and suitable for industrial automation, embedded controller design, and legacy system maintenance requiring stable component supply over extended product lifecycles.
Supply support for CD74ACT240E 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, with decades of heritage in industry-standard logic families.
The CD74ACT240E belongs to TI's CD74ACT high-speed CMOS logic series, engineered for TTL-compatible operation in industrial control, instrumentation, and computing systems demanding robustness and timing precision.
FAQ
What is the maximum operating temperature range for the CD74ACT240E?
The CD74ACT240E is rated for operation from −40°C to +85°C, meeting industrial temperature requirements. This range is validated per TI's Recommended Operating Conditions (Section 4.2), with absolute maximum ratings extending to −55°C to +125°C for short-duration stress conditions - though functional operation is guaranteed only within the −40°C to +85°C range.
Does the CD74ACT240E support 3.3V logic inputs?
No - the CD74ACT240E requires VCC = 4.5V–5.5V and has TTL-compatible input thresholds (VIH = 2.0V min, VIL = 0.8V max at VCC = 5V). A 3.3V logic high may not reliably meet VIH, risking metastability. For 3.3V systems, use CD74AC240E (1.5V–5.5V supply) or add level-shifting circuitry before the CD74ACT240E inputs.
How does the CD74ACT240E differ from the CD74AC240E?
The CD74ACT240E uses ACT (Advanced CMOS TTL-compatible) technology with tighter input thresholds (VIH = 2.0V, VIL = 0.8V) and faster propagation (≤8.6ns) at 5V, while CD74AC240E uses AC technology with wider supply range (1.5V–5.5V) but looser thresholds (VIH = 3.85V at 5.5V) and slower timing (≤10.1ns). They share identical pinout and 3-state functionality.
Can the CD74ACT240E drive a 50Ω transmission line directly?
Yes - the CD74ACT240E is explicitly characterized to drive 50Ω transmission lines at +85°C, verified per Section 4.5 footnote (2) of the datasheet. Its ±24mA output drive ensures adequate signal swing and edge rate (tr/tl ≤ 3ns) for clean impedance matching without external series resistors.
What is the purpose of the two separate output enables (1OE and 2OE) on the CD74ACT240E?
The dual active-low output enables (1OE on pin 1, 2OE on pin 19) independently control two 4-bit banks - allowing selective activation of Bank 1 (Y0–Y3) or Bank 2 (Y0–Y3) or both. This enables time-multiplexed bus sharing, isolated peripheral addressing, and glitch-free handshaking in multi-master systems without requiring external logic.
CD74ACT240E Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ACT
- 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:
- 24mA, 24mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
CD74ACT240E FAQ
1.How can I place an order for CD74ACT240E through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74ACT240E 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 CD74ACT240E reliable?
The price and inventory of CD74ACT240E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74ACT240E is usually 5 days.
3.What payment methods are accepted for CD74ACT240E?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74ACT240E transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74ACT240E?
CD74ACT240E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74ACT240E 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 CD74ACT240E?
For technical support, including CD74ACT240E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74ACT240E requirements.
6.How does Aetrix verify that CD74ACT240E is sourced from the original manufacturer or authorized distributors?
All CD74ACT240E 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 CD74ACT240E meets industry standards.
7.What is the process for return or replacement of CD74ACT240E?
All CD74ACT240E units undergo pre-shipment inspection (PSI). If there is an issue with CD74ACT240E, 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 CD74ACT240E part is unused and in its original packaging.
Return procedure for CD74ACT240E:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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