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Texas Instruments SN74ALS2240N
- Part No.:
- SN74ALS2240N
- Manufacturer:
- Texas Instruments
- Package:
- -
- Datasheet:
-
SN74ALS2240N.pdf
- Description:
- BUS DRIVER, ALS SERIES
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Inventory:2,272
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Product details
Overview
SN74ALS2240N from Texas Instruments is an octal 3-state buffer and line driver/MOS driver designed for high-capacitance MOS device interfacing, with 25-Ω integrated series output resistors, 4.5–5.5 V supply operation, 0°C to 70°C temperature range, and 20-pin PDIP (N) package. It serves in memory address buffering, clock distribution, and bus transceiver applications requiring fan-out enhancement and low-output-impedance drive.
For engineers reviewing the SN74ALS2240N datasheet, SN74ALS2240N pinout, SN74ALS2240N application, or SN74ALS2240N equivalent, this page delivers verified electrical specs, functional truth table, thermal characteristics, switching timing under 50-pF load, and validated alternative options for legacy system maintenance and replacement design.
Technical Context
The SN74ALS2240N implements two independent 4-bit noninverting buffers, each with separate 3-state enable (OE) control. Each I/O port integrates a 25-Ω series resistor to damp reflections and eliminate external termination components when driving MOS inputs.
It operates strictly in positive logic: outputs are active-high when OE is low; outputs enter high-impedance state when OE is high. Propagation delays range from 2 ns (min) to 10 ns (max) for A→Y transitions, and enable/disable times range from 2 ns to 20 ns depending on edge direction and output state.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage (VCC) | 4.5 V to 5.5 V - Ensures compatibility with standard 5-V TTL/ALS logic systems and stable operation across industrial voltage tolerances. |
| Output Drive (IOL / IOH) | ±15 mA - Supports direct connection to multiple MOS gate inputs without external current-limiting or pull-up components. |
| Propagation Delay (tPLH/tPHL) | 2 ns (min) to 10 ns (max) at CL = 50 pF - Enables reliable high-speed bus signaling in legacy computing and control backplanes. |
| 3-State Enable/Disable Time | tPZH = 2–10 ns; tPZL = 7–20 ns - Critical for glitch-free bus arbitration and time-multiplexed data sharing between multiple drivers. |
| Input Voltage Thresholds | VIH = 2.0 V min; VIL = 0.8 V max - Guarantees robust noise margin and interoperability with standard ALS/TTL input logic families. |
| Thermal Resistance (θJA) | 67°C/W (N package) - Defines maximum power dissipation limit (~23 mA ICC max) under still-air conditions for safe continuous operation. |
| Operating Temperature | 0°C to 70°C - Qualified for commercial-grade embedded systems, test equipment, and industrial control panels. |
Pinout & Package
SN74ALS2240N uses a 20-pin plastic dual in-line package (PDIP), 300-mil width, with standard through-hole mounting and JEDEC MS-001 compliant footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 11 | 1OE, 2OE | Active-low 3-state enable inputs for Group 1 (pins 2–9) and Group 2 (pins 12–19); assertion disables respective outputs to high-Z. |
| 2, 4, 6, 8 | 1A1–1A4 | Noninverting input terminals for first quad buffer group; drive corresponding Y outputs when OE is asserted. |
| 12, 14, 16, 18 | 1Y1–1Y4 | Noninverting 3-state outputs for Group 1; include internal 25-Ω series resistor for controlled edge rate and MOS gate drive. |
| 13, 15, 17, 19 | 2A1–2A4 | Noninverting input terminals for second quad buffer group; functionally identical to 1A1–1A4 but independently enabled. |
| 3, 5, 7, 9 | 2Y1–2Y4 | Noninverting 3-state outputs for Group 2; match 1Yx in drive strength, timing, and integrated series resistance. |
| 10 | GND | Ground reference for all logic and power domains; must be low-impedance connection to minimize ground bounce in high-fanout configurations. |
| 20 | VCC | +5 V supply rail; decoupling capacitor (0.1 µF ceramic) required near pin for transient current stability during output switching. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 25-Ω Series Output Resistors | Eliminates need for external termination resistors, reducing BOM count and PCB area while controlling signal edge rates for MOS gate drive. |
| Dual Independent 4-Bit Groups | Enables flexible bus partitioning: one group can drive address lines while the other handles data/control signals, each with separate enable control. |
| ALS Logic Family Compatibility | Meets ALS input thresholds and output drive specs, ensuring seamless integration into existing 74ALS-based systems without level-shifting. |
| Low Propagation Delay Variation | 2–10 ns delay window supports synchronous timing budgets in 20–50 MHz bus environments with predictable setup/hold margins. |
| High Fan-Out Capability | Drives up to 20+ MOS inputs per output (based on 15 mA sink/source and typical MOS gate capacitance), reducing need for cascaded buffers. |
Applications
| Memory Address Buffering | Legacy Bus Transceiver Interface |
|---|---|
|
Use Scenario: Driving address lines of static RAM or ROM arrays in 1980s–1990s microcomputer systems where capacitive loading exceeds single-driver capability. IC Role / Device Role / Timing Role: Noninverting 3-state buffer providing isolation and fan-out expansion between CPU address bus and memory module inputs. Use Value: Integrated 25-Ω resistors suppress ringing on long PCB traces; dual-group enables interleaved addressing without contention. |
Use Scenario: Bidirectional data path conditioning between ISA or VME bus segments and peripheral controllers using open-drain or MOS-compatible interfaces. IC Role / Device Role / Timing Role: Line driver/receiver with independent enable control per group, supporting time-multiplexed read/write cycles on shared bus lines. Use Value: Matched tPLH/tPHL ensures symmetrical timing for both directions; 15 mA drive sustains signal integrity across 6-inch backplane traces. |
| Clock Distribution Network | MOS Gate Driver for Legacy Logic |
|
Use Scenario: Distributing system clock or strobe signals to multiple synchronous devices (e.g., counters, shift registers) in industrial PLC modules. IC Role / Device Role / Timing Role: Low-skew buffer replicating clock edges with minimal added jitter; 3-state allows dynamic clock gating via OE control. Use Value: Sub-10 ns propagation delay preserves setup/hold timing margins; 25-Ω series resistance damps overshoot on unterminated clock lines. |
Use Scenario: Directly driving the gate terminals of discrete NMOS or CMOS transistors used in analog switch matrices or power control circuits. IC Role / Device Role / Timing Role: Voltage-level translator and current amplifier converting TTL logic levels to full-rail MOS gate drive with controlled slew rate. Use Value: Eliminates external gate resistors; ±15 mA output safely charges/discharges typical 100–500 pF gate capacitances within nanosecond-scale timing windows. |
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 |
|---|---|---|---|
| SN74AS2240N | Faster propagation delay (1.5–7 ns vs. 2–10 ns) and higher drive (±20 mA), but higher ICC (up to 30 mA) and stricter VIH/VIL thresholds. | Better suited for high-speed backplanes (>40 MHz), but may overdrive legacy MOS loads or exceed power budgets in low-power designs. | Select SN74AS2240N only if timing budget requires sub-7 ns delay and system power budget accommodates +30% ICC increase. |
| SN74LS240N | Lower drive (±15 mA same), no integrated series resistors, higher VOL (0.5 V max @ 24 mA), and wider propagation spread (15–35 ns). | Requires external 33–51 Ω series resistors for clean MOS gate drive; slower timing limits use in >10 MHz systems. | Choose SN74LS240N only when cost is primary constraint and board layout allows space for discrete termination resistors. |
Compared with SN74ALS2240N, SN74AS2240N offers speed at the cost of power and compatibility, while SN74LS240N trades integrated termination and timing precision for lower unit cost and broader legacy availability.
Availability
SN74ALS2240N is available at Aetrix Electronics and suitable for memory subsystem upgrades, industrial control panel refurbishment, and legacy test equipment repair requiring stable component supply and traceable sourcing.
Supply support for SN74ALS2240N 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 founded in 1930, specializing in analog, logic, embedded processing, and power management ICs for industrial, automotive, and communications markets.
The SN74ALS2240N belongs to TI's 74ALS logic family, engineered for high-speed, low-power bipolar implementation of standard TTL-compatible functions in commercial-temperature embedded systems.
FAQ
What is the operating voltage range for the SN74ALS2240N?
The SN74ALS2240N operates over a supply voltage range of 4.5 V to 5.5 V, with recommended nominal operation at 5 V. This range ensures compatibility with standard 5-V TTL and ALS logic families while maintaining specified VOH, VOL, and timing performance across process and temperature variations.
Does the SN74ALS2240N require external series resistors for MOS gate drive?
No, the SN74ALS2240N does not require external series resistors for MOS gate drive because it integrates 25-Ω series resistors on all eight outputs. These resistors damp signal reflections and control edge rates, enabling direct connection to capacitive MOS inputs without additional components.
How many independent 3-state groups does the SN74ALS2240N contain?
The SN74ALS2240N contains two independent 4-bit 3-state buffer groups: Group 1 (pins 1, 2, 4, 6, 8, 12, 14, 16, 18) and Group 2 (pins 11, 13, 15, 17, 19, 3, 5, 7, 9). Each group has its own active-low enable input (1OE and 2OE), allowing asynchronous control of output states.
What is the maximum output current specification for the SN74ALS2240N?
The SN74ALS2240N specifies ±15 mA maximum output current per pin - –15 mA for sourcing (IOH) and +15 mA for sinking (IOL) - measured under recommended operating conditions (VCC = 4.5 V). This rating supports direct drive of multiple MOS gate inputs or TTL-compatible loads without external amplification.
Is the SN74ALS2240N pin-compatible with other 74-series octal buffers?
The SN74ALS2240N shares the same 20-pin PDIP (N) footprint and pinout as SN74LS240N and SN74AS2240N, including identical VCC (pin 20), GND (pin 10), and I/O assignments. However, differences in internal series resistance, timing, and drive strength mean functional substitution requires verification of system-level timing and loading requirements.
SN74ALS2240N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- -
- Number of Elements:
- -
- Number of Bits per Element:
- -
- Input Type:
- -
- Output Type:
- -
- Current - Output High, Low:
- -
- Voltage - Supply:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
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SN74ALS2240N FAQ
1.How can I place an order for SN74ALS2240N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS2240N 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 SN74ALS2240N reliable?
The price and inventory of SN74ALS2240N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS2240N is usually 5 days.
3.What payment methods are accepted for SN74ALS2240N?
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4.How is shipping managed for SN74ALS2240N?
SN74ALS2240N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS2240N 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 SN74ALS2240N?
For technical support, including SN74ALS2240N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS2240N requirements.
6.How does Aetrix verify that SN74ALS2240N is sourced from the original manufacturer or authorized distributors?
All SN74ALS2240N 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 SN74ALS2240N meets industry standards.
7.What is the process for return or replacement of SN74ALS2240N?
All SN74ALS2240N units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS2240N, 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 SN74ALS2240N part is unused and in its original packaging.
Return procedure for SN74ALS2240N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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