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Texas Instruments SN74ALS240A-1DBRG4
- Part No.:
- SN74ALS240A-1DBRG4
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74ALS240A-1DBRG4.pdf
- Description:
- IC BUFFER INVERT 5.5V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,141
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Product details
Overview
SN74ALS240A-1DBRG4 from Texas Instruments is an octal noninverting buffer/driver with 3-state outputs in a 20-pin SSOP (DB) package, designed for memory address driving and bus interfacing. It operates at 4.5–5.5 V, delivers 48 mA low-level output current (IOL), supports 9 ns max propagation delay (tPHL), and features pnp inputs to reduce DC loading on upstream logic.
For engineers reviewing the SN74ALS240A-1DBRG4 datasheet, SN74ALS240A-1DBRG4 pinout, SN74ALS240A-1DBRG4 application, or SN74ALS240A-1DBRG4 equivalent, this page provides verified electrical specs, functional role in bus buffering, thermal data for SSOP-20 layout, and validated drop-in alternatives for legacy TTL system upgrades.
Technical Context
The SN74ALS240A-1DBRG4 implements dual 4-bit noninverting buffers with independent 3-state control via two active-low OE inputs (1OE, 2OE). Each buffer pair drives one direction of bidirectional address/data paths, enabling high-fan-out bus isolation without signal inversion.
Its ALS (Advanced Low-Power Schottky) process ensures compatibility with standard TTL logic levels while reducing power consumption versus original LS families. The -1 suffix denotes enhanced IOL capability (48 mA vs. 24 mA in standard SN74ALS240A), validated only at VCC = 4.75–5.25 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - Ensures robust operation across industrial-grade 5 V rails with ±10% tolerance. |
| IOL (max) | 48 mA - Enables direct drive of heavy capacitive loads (e.g., >100 pF buses) without external amplification. |
| tPHL / tPLH | 9 ns max - Supports high-speed address latching in 10+ MHz memory subsystems with tight timing margins. |
| VIH / VIL | 2.0 V / 0.8 V - Guarantees noise-immune recognition of TTL-compatible logic thresholds at 5 V supply. |
| θJA (SSOP) | 70 °C/W - Requires minimal PCB copper area for thermal management in compact embedded designs. |
| ICC (outputs disabled) | 14–25 mA - Defines quiescent power draw during bus arbitration or standby, critical for power budgeting. |
Pinout & Package
SN74ALS240A-1DBRG4 uses a 20-pin Small Outline Shrink Plastic (SSOP-20) package (DB), 7.4 mm × 5.6 mm × 2.0 mm height, RoHS-compliant NiPdAu lead finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE | Output Enable (active-low) | Controls Y1–Y4 outputs; asserted low enables all four buffers in first group. |
| 2OE | Output Enable (active-low) | Controls Y5–Y8 outputs; independent control allows split-bus gating. |
| 1A1–1A4 | Input (Group 1) | Noninverting inputs for first four buffers; pnp input structure reduces loading on preceding drivers. |
| 2A1–2A4 | Input (Group 2) | Noninverting inputs for second four buffers; electrically isolated from Group 1 for dual-bus use. |
| 1Y1–1Y4 | Output (Group 1) | 3-state noninverting outputs driven by 1A1–1A4 when 1OE = L. |
| 2Y1–2Y4 | Output (Group 2) | 3-state noninverting outputs driven by 2A1–2A4 when 2OE = L. |
| VCC | Power supply | 5 V nominal supply; must be decoupled locally due to fast switching transients. |
| GND | Ground reference | Common return path; requires low-inductance connection to minimize ground bounce. |
Key Features
| Feature | Design Value |
|---|---|
| High fan-out capability | Drives ≥20 standard TTL loads per output, eliminating need for cascaded buffers in dense address routing. |
| pnp input structure | Reduces input current to ≤–0.1 mA at VIL, minimizing loading on clock generators or microcontroller GPIOs. |
| Independent 3-state control | Dual OE pins allow selective enable/disable of two 4-bit channels-essential for bidirectional bus arbitration. |
| ALS process optimization | Combines LS speed with lower ICC (14–25 mA disabled) versus standard LS, improving power efficiency in always-on systems. |
Applications
| Memory Address Buffering | Legacy Bus Interface |
|---|---|
Use Scenario: Driving 16-bit address lines from a microprocessor to multiple SRAM chips in a 1980s–1990s embedded controller. IC Role / Device Role / Timing Role: Noninverting buffer isolating CPU address bus from distributed capacitive load; 3-state enables shared bus access with DMA controllers. Use Value: Prevents address skew and timing violations caused by trace capacitance, supporting reliable 8–10 MHz operation. | Use Scenario: Interfacing Z80 or 8086-based CPU boards with peripheral cards using ISA-style parallel backplanes. IC Role / Device Role / Timing Role: Bidirectional bus driver translating between processor-side and card-side logic levels with independent channel gating. Use Value: Eliminates level-shifter components and simplifies board layout by integrating dual 4-bit buffering with OE-controlled directionality. |
| Industrial Control Backplane | Test Equipment Signal Routing |
Use Scenario: Distributing real-time I/O address signals across modular PLC racks with long parallel ribbon cables. IC Role / Device Role / Timing Role: High-current buffer maintaining signal integrity over 30 cm traces; pnp inputs prevent voltage droop on source drivers. Use Value: Sustains clean logic transitions despite cable capacitance up to 150 pF, avoiding false triggers in safety-critical modules. | Use Scenario: Configurable signal routing matrix in automated test equipment (ATE) switching between DUT pins and measurement instruments. IC Role / Device Role / Timing Role: 3-state multiplexer enabling dynamic reconfiguration of test paths without hardware changes. Use Value: Reduces test setup time by allowing software-controlled bus isolation, supporting concurrent stimulus/response measurements. |
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 |
|---|---|---|---|
| SN74ALS240ADBR | No -1 suffix; rated IOL = 24 mA (not 48 mA); identical pinout and AC specs. | Suitable where bus load < 50 pF or lower drive strength suffices; not for high-capacitance legacy backplanes. | Select SN74ALS240ADBR only if design validation confirms 24 mA IOL meets timing margin requirements. |
| SN74AS240ADBR | Faster tPHL/tPLH (6.5 ns max vs. 9 ns); higher ICC (51–75 mA); AS process, not ALS. | Better for speed-critical paths but increases power and EMI; requires tighter decoupling and layout control. | Choose SN74AS240ADBR when propagation delay dominates timing budgets and thermal/power constraints allow. |
Compared with SN74ALS240ADBR, SN74ALS240A-1DBRG4 delivers double the sink current for marginal bus loads, while SN74AS240ADBR trades 30% faster switching for 2× higher supply current-making the -1 variant optimal for reliability-focused legacy upgrades where drive strength is limiting.
Availability
SN74ALS240A-1DBRG4 is available at Aetrix Electronics and suitable for memory address buffering, legacy bus interface, and industrial control backplane applications requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74ALS240A-1DBRG4 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, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74ALS240A-1DBRG4 belongs to TI's legacy TTL logic family, engineered specifically to upgrade LS-TTL systems with improved speed-power trade-offs and enhanced drive capability for memory and bus applications.
FAQ
What is the maximum operating temperature range for SN74ALS240A-1DBRG4?
The SN74ALS240A-1DBRG4 is rated for commercial operation from 0°C to +70°C, consistent with its SN74xxx ALS family classification and SSOP-20 packaging. This range aligns with standard industrial ambient conditions and excludes extended temperature variants like SN54ALS240A (-55°C to +125°C).
Does SN74ALS240A-1DBRG4 support true bidirectional data flow?
No, SN74ALS240A-1DBRG4 is a noninverting buffer only-it does not support bidirectional data transfer. It provides unidirectional signal conditioning with independent 3-state control per 4-bit group (1Y1–1Y4 and 2Y1–2Y4), requiring external logic for full bidirectional bus management.
Can SN74ALS240A-1DBRG4 replace SN74LS240 in existing designs?
Yes, SN74ALS240A-1DBRG4 is a direct functional and pin-compatible upgrade for SN74LS240, offering faster propagation delays (9 ns vs. 15 ns), lower power consumption, and higher output drive (48 mA vs. 24 mA), provided VCC remains within 4.5–5.5 V and layout accommodates SSOP-20 footprint.
What is the purpose of the pnp input structure in SN74ALS240A-1DBRG4?
SN74ALS240A-1DBRG4 uses pnp input transistors to reduce input current draw-limiting IIL to –0.1 mA at VIL-thereby minimizing loading on upstream drivers such as microcontroller GPIOs or clock sources, preserving signal integrity and timing margins in high-fan-out configurations.
Is SN74ALS240A-1DBRG4 RoHS compliant and lead-free?
Yes, SN74ALS240A-1DBRG4 is RoHS compliant with NiPdAu lead finish and qualifies under TI's "Yes" RoHS status. It meets JEDEC J-STD-020 moisture sensitivity Level-1 (unlimited floor life at ≤30°C/60% RH) and is compatible with standard Pb-free reflow profiles.
SN74ALS240A-1DBRG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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, 48mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74ALS240A-1DBRG4 FAQ
1.How can I place an order for SN74ALS240A-1DBRG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS240A-1DBRG4 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 SN74ALS240A-1DBRG4 reliable?
The price and inventory of SN74ALS240A-1DBRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS240A-1DBRG4 is usually 5 days.
3.What payment methods are accepted for SN74ALS240A-1DBRG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS240A-1DBRG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS240A-1DBRG4?
SN74ALS240A-1DBRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS240A-1DBRG4 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 SN74ALS240A-1DBRG4?
For technical support, including SN74ALS240A-1DBRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS240A-1DBRG4 requirements.
6.How does Aetrix verify that SN74ALS240A-1DBRG4 is sourced from the original manufacturer or authorized distributors?
All SN74ALS240A-1DBRG4 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 SN74ALS240A-1DBRG4 meets industry standards.
7.What is the process for return or replacement of SN74ALS240A-1DBRG4?
All SN74ALS240A-1DBRG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS240A-1DBRG4, 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 SN74ALS240A-1DBRG4 part is unused and in its original packaging.
Return procedure for SN74ALS240A-1DBRG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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