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Texas Instruments CD74AC240EE4
- Part No.:
- CD74AC240EE4
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
CD74AC240EE4.pdf
- Description:
- 8-CH, 1.5-V TO 5.5-V INVERTERS W
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
CD74AC240EE4 from Texas Instruments is a 20-pin PDIP-packaged octal inverting buffer/line driver with dual active-low 3-state outputs, operating from 1.5 V to 5.5 V, delivering ±24 mA output drive per pin and supporting 50 Ω transmission-line driving - used in bus interface and address/data buffering in industrial control systems.
For engineers reviewing the CD74AC240EE4 datasheet, CD74AC240EE4 pinout, CD74AC240EE4 application, or CD74AC240EE4 equivalent, key selection criteria include its AC-series voltage range (1.5–5.5 V), balanced propagation delays (e.g., 6.5 ns max tPHL at 5 V), dual bank 3-state control (1OE/2OE), and compatibility with FAST IC fanout (15 loads).
Technical Context
The CD74AC240EE4 implements two independent 4-bit inverting buffer banks, each controlled by its own active-low output enable (1OE, 2OE). Its RCA Advanced CMOS process ensures SCR latch-up resistance and enables operation across −40°C to +85°C.
It features balanced tPLH/tPHL propagation delays (≤7.2 ns at 5 V), low 3-state leakage (±5 μA max), and input/output voltage thresholds scaled to 30% of VCC for robust noise immunity - critical for mixed-voltage digital interfacing in legacy and modern embedded systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 1.5 V to 5.5 V - supports single-supply operation across 3.3 V and 5 V logic domains without level shifters. |
| Output Drive | ±24 mA per pin - directly drives 50 Ω transmission lines or fans out to 15 FAST ICs without external buffers. |
| Propagation Delay | ≤7.2 ns (tPHL, VCC = 5 V) - enables high-speed bus buffering in ≤100 MHz clocked systems. |
| Input Threshold | VIL ≤ 0.9 V, VIH ≥ 2.1 V at 3 V - provides 30% noise margin relative to supply, enhancing reliability in noisy industrial environments. |
| Quiescent Current | ≤80 μA (TA = −40°C to +85°C) - enables low-power standby in battery-backed or energy-conscious designs. |
| Operating Temp | −40°C to +85°C - qualified for industrial temperature range, suitable for factory automation and motor control applications. |
| Package | PDIP-20 (N), body size 24.33 mm × 6.35 mm - through-hole compatible for prototyping, legacy PCBs, and high-reliability manual assembly. |
Pinout & Package
Packaged in 20-pin plastic dual in-line package (PDIP-N), with 0.3-inch width, 2.54 mm pitch, and through-hole mounting. Pin 10 is GND; Pin 20 is VCC; dual output-enable pins (1OE, 2OE) are active-low and independently control Bank 1 (pins 2,4,6,8 → 12,14,16,18) and Bank 2 (pins 11,13,15,17 → 3,5,7,9).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE | Active-low enable for Bank 1 outputs | Drives Bank 1 (1Y0–1Y3) when low; places them in high-impedance state when high - enables time-multiplexed bus sharing. |
| 1A0–1A3 | Bank 1 input channels | Inverting inputs: 1A0 drives 1Y0, etc.; supports asynchronous data latching when paired with external clocks or enables. |
| 1Y0–1Y3 | Bank 1 inverted output channels | Active only when 1OE = L; outputs complement of corresponding 1Ax - used for polarity-inverted bus drivers or signal inversion stages. |
| 2OE | Active-low enable for Bank 2 outputs | Independent control of Bank 2 (2Y0–2Y3); allows simultaneous or staggered enable of two 4-bit data paths. |
| 2A0–2A3 | Bank 2 input channels | Inverting inputs feeding Bank 2 outputs; electrically isolated from Bank 1 - supports dual-bus isolation or mirrored channel buffering. |
| 2Y0–2Y3 | Bank 2 inverted output channels | Complement outputs enabled by 2OE; identical timing and drive strength to Bank 1 - ensures matched delay between parallel data lanes. |
| GND (Pin 10) | Ground reference | Primary return path for all I/O and supply currents; must be low-impedance to maintain noise immunity and switching integrity. |
| VCC (Pin 20) | Positive supply | Single power rail for entire device; requires local 0.1 µF bypass capacitor per VCC pin to suppress switching transients. |
Key Features
| Feature | Design Value |
|---|---|
| SCR-latch-up-resistant CMOS | Guarantees immunity to destructive latch-up under transient overvoltage or ESD events - essential for industrial field-deployed equipment. |
| Balanced propagation delays | tPLH and tPHL match within 1 ns (at 5 V), minimizing skew across 8-bit data paths and preserving setup/hold timing margins. |
| 1.5 V to 5.5 V operation | Eliminates need for separate voltage translators when interfacing 1.8 V, 3.3 V, and 5 V subsystems - reduces BOM count and layout complexity. |
| ±24 mA output drive | Supports direct connection to unterminated 50 Ω traces or legacy TTL loads without series termination resistors or buffer amplifiers. |
| 3-state output control | Dual independent enables (1OE/2OE) allow selective activation of either 4-bit bank - enabling flexible bus arbitration and partial data masking. |
Applications
| Industrial PLC Backplane Interface | Legacy Microprocessor Address Bus Driver |
|---|---|
Use Scenario: Driving multiplexed address/data lines between CPU and I/O modules in programmable logic controllers with long backplane traces. IC Role / Device Role / Timing Role: Inverting 3-state buffer providing bidirectional bus isolation and slew-controlled signal integrity on 50 Ω routed traces. Use Value: ±24 mA drive and 7.2 ns propagation delay ensure clean edge transitions across 30 cm backplane runs at 20 MHz clock rates. | Use Scenario: Buffering 8-bit address segments from Z80 or 8085 microprocessors to peripheral decoders in retro-computing or test equipment. IC Role / Device Role / Timing Role: Octal inverting driver translating TTL-compatible outputs to CMOS levels while enabling/disabling segments via 1OE/2OE. Use Value: 1.5–5.5 V supply range matches both 5 V TTL logic and newer low-voltage peripherals; dual enables simplify address window gating. |
| Automated Test Equipment (ATE) Signal Conditioning | Industrial Sensor Data Aggregation Node |
Use Scenario: Level-shifting and isolating digital control signals between FPGA-based controller and high-voltage relay driver boards. IC Role / Device Role / Timing Role: Inverting buffer with independent 3-state control per 4-bit group, enabling safe hot-swap of submodules without bus contention. Use Value: Balanced tPLH/tPHL and low 3-state leakage (±5 μA) prevent false triggering during enable transitions in multi-board synchronized systems. | Use Scenario: Consolidating digital outputs from multiple analog sensor front-ends (e.g., ADC status flags, fault indicators) onto a shared microcontroller input bus. IC Role / Device Role / Timing Role: Low-power octal buffer aggregating discrete status bits with independent enable control for power-gated sensor clusters. Use Value: Quiescent current ≤80 μA at +85°C allows continuous monitoring in thermally constrained enclosures without thermal runaway. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal inverting buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AC240N | Same AC logic family, identical pinout and electrical specs; TI second-source part with identical PDIP-20 packaging and −40°C to +85°C rating. | No functional difference; fully interchangeable in existing designs requiring no layout or firmware changes. | Select when sourcing flexibility or dual-sourcing strategy is required without design revalidation. |
| CD74ACT240EE4 | TTL-compatible input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V), 4.5–5.5 V only supply range, slightly faster propagation (≤6.5 ns tPHL at 5 V). | Requires 5 V-only system; better suited for pure TTL environments or where tighter timing margins are needed. | Choose for legacy 5 V systems demanding higher speed and TTL-level compatibility - not for mixed-voltage or sub-3.3 V operation. |
Compared with SN74AC240N, CD74AC240EE4 offers identical functionality and drop-in compatibility; versus CD74ACT240EE4, it trades wider voltage range and lower power for slightly relaxed timing - making it optimal for flexible-voltage industrial interfaces rather than pure 5 V speed-critical paths.
Availability
CD74AC240EE4 is available at Aetrix Electronics and suitable for industrial automation, legacy microprocessor support, and test equipment requiring stable component supply with long-term manufacturability and RoHS-compliant through-hole packaging.
Supply support for CD74AC240EE4 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 company specializing in analog and embedded processing technologies, with leadership in industrial, automotive, and communications markets.
The CD74AC240EE4 belongs to TI's legacy CMOS logic portfolio, designed specifically for robust, wide-voltage-range digital interfacing in harsh industrial environments where reliability, latch-up immunity, and long-term supply stability are critical.
FAQ
What is the maximum supply voltage rating for CD74AC240EE4?
The CD74AC240EE4 has an absolute maximum supply voltage (VCC) of 6 V, but its recommended operating range is 1.5 V to 5.5 V. Operation above 5.5 V risks exceeding specified electrical characteristics and may compromise long-term reliability. The device is optimized for stable performance across 3.3 V and 5 V logic domains, and CD74AC240EE4 must not be operated continuously beyond 5.5 V in production systems.
Does CD74AC240EE4 support non-inverting logic functions?
No, CD74AC240EE4 is strictly an inverting octal buffer - each input (e.g., 1A0) drives a complemented output (1Y0). It does not provide non-inverting functionality. For non-inverting 3-state octal buffering, TI's CD74AC244EE4 or SN74AC244N would be appropriate alternatives, as they share identical package, pinout, and voltage specifications but implement true (non-inverting) buffering.
What is the thermal resistance (RθJA) of CD74AC240EE4 in its PDIP package?
The junction-to-ambient thermal resistance (RθJA) for CD74AC240EE4 in the PDIP-20 (N) package is 40°C/W, as specified in the official Texas Instruments datasheet. This value assumes standard JEDEC 2-layer board conditions and confirms suitability for industrial ambient temperatures up to +85°C without forced airflow or heatsinking in typical PCB layouts with adequate copper pour.
Can CD74AC240EE4 drive 75 Ω coaxial cables reliably?
CD74AC240EE4 is characterized for reliable 50 Ω transmission-line driving at +85°C, but not for 75 Ω. At +125°C, the datasheet specifies 75 Ω capability only for military-grade CD54AC240 variants. For 75 Ω applications at industrial temperatures, signal integrity degradation (e.g., overshoot, reflection) may occur; use of external series termination or dedicated line drivers is recommended when deploying CD74AC240EE4 in 75 Ω systems.
Is CD74AC240EE4 pin-compatible with CD74ACT240EE4?
Yes, CD74AC240EE4 and CD74ACT240EE4 share identical PDIP-20 pinout, terminal functions, and mechanical footprint. However, they differ in input threshold compatibility (AC: 30% VCC; ACT: TTL-level), supply range (AC: 1.5–5.5 V; ACT: 4.5–5.5 V), and propagation delay (ACT is ~0.7 ns faster). They are physically interchangeable but require validation of voltage and timing margins before substitution.
CD74AC240EE4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AC
- 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:
- 1.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
CD74AC240EE4 FAQ
1.How can I place an order for CD74AC240EE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74AC240EE4 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 CD74AC240EE4 reliable?
The price and inventory of CD74AC240EE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74AC240EE4 is usually 5 days.
3.What payment methods are accepted for CD74AC240EE4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74AC240EE4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74AC240EE4?
CD74AC240EE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74AC240EE4 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 CD74AC240EE4?
For technical support, including CD74AC240EE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74AC240EE4 requirements.
6.How does Aetrix verify that CD74AC240EE4 is sourced from the original manufacturer or authorized distributors?
All CD74AC240EE4 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 CD74AC240EE4 meets industry standards.
7.What is the process for return or replacement of CD74AC240EE4?
All CD74AC240EE4 units undergo pre-shipment inspection (PSI). If there is an issue with CD74AC240EE4, 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 CD74AC240EE4 part is unused and in its original packaging.
Return procedure for CD74AC240EE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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