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Texas Instruments SN74AS240ADWR
- Part No.:
- SN74AS240ADWR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74AS240ADWR.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,491
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Product details
Overview
SN74AS240ADWR from Texas Instruments is an octal noninverting buffer/driver with 3-state outputs, designed for memory address driving, bus interfacing, and clock distribution in TTL-compatible systems. It operates at 4.5–5.5 V, delivers ±64 mA output drive, supports 6.5 ns typical propagation delay, and features symmetrical active-low output-enable (OE) inputs for bidirectional bus control in industrial and embedded computing applications.
For engineers reviewing the SN74AS240ADWR datasheet, SN74AS240ADWR pinout, SN74AS240ADWR application, or SN74AS240ADWR equivalent, this page provides verified functional specifications, SOIC-20 package details, real-world use cases in address buffering and bus isolation, and validated alternative parts for design continuity and sourcing flexibility.
Technical Context
The SN74AS240ADWR implements dual 4-bit noninverting buffer sections (Group 1: A1–A4 → Y1–Y4; Group 2: A1–A4 → Y1–Y4), each controlled by independent active-low OE inputs (1OE, 2OE). Its AS-family bipolar transistor architecture enables high-speed switching with low propagation delay and strong current sourcing/sinking capability.
It uses pnp input stages to reduce DC loading on upstream logic, supports hot-swappable 3-state bus operation via fast enable/disable timing (tPZH ≤ 6.4 ns, tPLZ ≤ 9.5 ns), and maintains stable output impedance in high-impedance state (IOZH/IOZL ≤ ±50 µA at 5.5 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures compatibility with standard 5 V TTL and CMOS systems without level-shifting. |
| Output Drive (IOL/IOH) | 64 mA sink / –15 mA source - Supports direct driving of heavy capacitive loads or multiple TTL inputs without external buffers. |
| Propagation Delay (tPLH/tPHL) | 1 ns min / 6.5 ns max - Enables reliable operation in high-speed address/data paths up to ~150 MHz system clock domains. |
| 3-State Enable Time (tPZH) | 1.2 ns min / 5 ns max - Allows rapid bus arbitration and minimizes contention windows during multi-master access. |
| Input Threshold (VIL/VIH) | 0.8 V max low / 2.0 V min high - Guarantees noise margin >0.4 V in 5 V systems with typical TTL fan-out. |
| Quiescent Current (ICC) | 24–38 mA (outputs disabled) - Predictable power budgeting for standby-mode power analysis in memory subsystems. |
| Package | SOIC-20 (DW) - Standard surface-mount footprint compatible with automated assembly and IPC-7351 land patterns. |
Pinout & Package
SN74AS240ADWR is housed in a 20-pin SOIC (DW) package measuring 13.0 mm × 7.6 mm × 2.65 mm, with 1.27 mm pitch, gull-wing leads, and RoHS-compliant NiPdAu plating (Level-1 MSL rating).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 2OE | Active-low output enable | Independent control of Group 1 (pins 3,5,7,9) and Group 2 (pins 18,16,14,12) 3-state outputs; low = enabled, high = high-Z. |
| 1A1–1A4, 2A1–2A4 | Buffer inputs | Eight noninverting data inputs (1A1→1Y1, etc.); pnp input structure reduces input current loading on drivers. |
| 1Y1–1Y4, 2Y1–2Y4 | Buffer outputs | Eight 3-state noninverting outputs; capable of sinking 64 mA or sourcing 15 mA while maintaining VOH ≥ 2.4 V / VOL ≤ 0.55 V. |
| VCC (pin 20), GND (pin 10) | Power supply | Single 5 V supply rail; decoupling required within 10 mm of pins 20/10 to maintain switching integrity. |
Key Features
| Feature | Design Value |
|---|---|
| High-speed AS logic family | 6.5 ns max propagation delay enables use in sub-10 ns address strobe timing windows for SRAM and ROM interfaces. |
| Dual independent 4-bit groups | Separate 1OE/2OE controls allow asymmetric bus partitioning - e.g., isolate address MSBs and LSBs under different control signals. |
| Robust 3-state output control | tPHZ ≤ 5 ns and tPLZ ≤ 9.5 ns ensure clean bus release before next driver asserts, preventing signal contention in shared-bus systems. |
| pnp input stage | Reduces input current (IIL ≤ –1 mA) versus standard TTL, lowering loading on preceding gates and improving fan-in scalability. |
| Industrial temperature range | 0°C to 70°C operation supports deployment in commercial and industrial embedded controllers without derating. |
Applications
| Memory Address Buffering | System Bus Isolation |
|---|---|
Use Scenario: Driving 16-bit address lines from a microcontroller to multiple SRAM chips sharing a common address bus. IC Role / Device Role / Timing Role: Noninverting octal buffer with dual OE control isolates address segments and prevents bus contention during chip-select transitions. Use Value: 64 mA sink capability ensures full logic swing across 100 pF+ trace capacitance; 6.5 ns delay preserves setup/hold timing margins for 25 ns SRAM access cycles. | Use Scenario: Separating CPU data bus from peripheral I/O bus in an 8-bit embedded system with DMA-capable peripherals. IC Role / Device Role / Timing Role: Bidirectional bus driver enabling CPU-to-peripheral and peripheral-to-CPU data flow using separate OE-controlled groups. Use Value: Independent 1OE/2OE allows simultaneous read/write arbitration; fast 3-state disable (<9.5 ns) eliminates bus turnaround dead time. |
| Clock Distribution | Legacy TTL System Interface |
Use Scenario: Distributing a 12 MHz system clock to four synchronous peripherals requiring phase-aligned, low-skew inputs. IC Role / Device Role / Timing Role: Low-jitter noninverting buffer replicating clock signal with matched group delays across all eight outputs. Use Value: Matched tPLH/tPHL (±0.5 ns typical) minimizes inter-output skew; 15 mA sourcing drives 50 Ω transmission lines directly. | Use Scenario: Interfacing modern microcontrollers with legacy TTL-based instrumentation modules lacking 3.3 V tolerance. IC Role / Device Role / Timing Role: Level-translating buffer providing 5 V TTL-compatible outputs while accepting 3.3 V logic-high inputs via VIH = 2.0 V threshold. Use Value: Guaranteed VIH ≥ 2.0 V and VIL ≤ 0.8 V ensures interoperability with mixed-voltage designs without external resistors or translators. |
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 |
|---|---|---|---|
| SN74ALS240ADWR | ALS family: lower drive (24 mA IOL), slower speed (9 ns max tPHL), higher noise immunity (VIK = –1.2 V). | Better suited for low-power, noise-sensitive industrial control where speed <10 MHz suffices. | Select when power efficiency and EMI robustness outweigh raw speed requirements. |
| SN74F240N | F-family: 35 mA IOL, 8 ns max tPHL, PDIP-20 only, no tape-and-reel option. | Limited to through-hole prototyping or legacy board rework; lacks SOIC packaging and modern MSL compliance. | Choose only for hand-soldered evaluation or replacement in existing PDIP-based systems. |
Compared with SN74ALS240ADWR and SN74F240N, the SN74AS240ADWR delivers the highest output drive and fastest propagation in SOIC-20 packaging, making it optimal for high-density, high-speed bus interface designs requiring both performance and manufacturability.
Availability
SN74AS240ADWR is available at Aetrix Electronics and suitable for memory subsystem design, industrial bus interface development, and legacy TTL system integration requiring stable component supply, long-term lifecycle support, and RoHS-compliant manufacturing.
Supply support for SN74AS240ADWR 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 delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74AS240ADWR belongs to TI's 74AS logic family, engineered for high-speed, high-drive digital interfacing in memory, bus, and clock distribution systems where TTL compatibility and timing precision are critical.
FAQ
What is the maximum output sink current specification for SN74AS240ADWR?
The SN74AS240ADWR is rated for a maximum low-level output current (IOL) of 64 mA per output, tested at VCC = 4.5 V and VOL ≤ 0.55 V. This value is confirmed in the "Electrical Characteristics" table for SN74AS240A on page 5 of the SDAS214E datasheet. The SN74AS240ADWR meets this specification in its SOIC-20 DW package under industrial temperature conditions (0°C to 70°C).
Does SN74AS240ADWR support hot-swapping on a live bus?
While SN74AS240ADWR features fast 3-state enable/disable timing (tPLZ ≤ 9.5 ns, tPHZ ≤ 5 ns), it does not include bus-hold, power-up 3-state, or Ioff protection. Hot-swapping requires external current limiting and sequencing control; TI recommends using dedicated hot-swap controllers or verifying system-level fault tolerance before live insertion. The SN74AS240ADWR itself is not characterized for hot-swap stress conditions.
What is the pin 1 marking and orientation for SN74AS240ADWR in tape-and-reel format?
SN74AS240ADWR is marked "AS240A" on the top surface, with pin 1 located in Quadrant Q1 of the carrier tape (per TI's Package Materials Information, August 2026). The device uses standard SOIC-20 DW packaging with a 1.27 mm pitch, and the reel orientation follows JEDEC-standard pocket quadrant assignment for automated placement.
Can SN74AS240ADWR be used with 3.3 V logic inputs?
Yes - SN74AS240ADWR accepts 3.3 V logic-high inputs reliably because its VIH (minimum high-level input voltage) is specified at 2.0 V across the operating temperature range. With a 3.3 V signal, the input exceeds VIH by 1.3 V, ensuring solid logic-high recognition. However, outputs remain 5 V TTL levels, so level translation may be needed downstream if interfacing with 3.3 V receivers.
Is there a drop-in replacement for SN74AS240ADWR in the same SOIC-20 package?
No pin-compatible drop-in replacement exists with identical AC/DC specifications. SN74ALS240ADWR shares the same pinout and SOIC-20 package but offers lower drive (24 mA) and slower speed (9 ns). SN74F240N has matching functionality but only in PDIP-20. For true functional equivalence in SOIC-20, SN74AS240ADWR remains the sole TI offering in its speed/drive class.
SN74AS240ADWR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Cut Tape (CT)
- 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:
- 15mA, 64mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74AS240ADWR FAQ
1.How can I place an order for SN74AS240ADWR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AS240ADWR 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 SN74AS240ADWR reliable?
The price and inventory of SN74AS240ADWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AS240ADWR is usually 5 days.
3.What payment methods are accepted for SN74AS240ADWR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AS240ADWR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AS240ADWR?
SN74AS240ADWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AS240ADWR 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 SN74AS240ADWR?
For technical support, including SN74AS240ADWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AS240ADWR requirements.
6.How does Aetrix verify that SN74AS240ADWR is sourced from the original manufacturer or authorized distributors?
All SN74AS240ADWR 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 SN74AS240ADWR meets industry standards.
7.What is the process for return or replacement of SN74AS240ADWR?
All SN74AS240ADWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AS240ADWR, 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 SN74AS240ADWR part is unused and in its original packaging.
Return procedure for SN74AS240ADWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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