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Texas Instruments SN74ALS1245ADW
- Part No.:
- SN74ALS1245ADW
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS1245ADW.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,582
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Product details
Overview
SN74ALS1245ADW from Texas Instruments is an octal bidirectional bus transceiver with 3-state outputs in a 20-pin SOIC (DW) package, operating at 4.5–5.5 V, supporting asynchronous A↔B data flow under DIR control and isolation via OE, commonly used in legacy industrial backplane and memory-mapped I/O expansion systems.
For engineers reviewing the SN74ALS1245ADW datasheet, SN74ALS1245ADW pinout, SN74ALS1245ADW application, or SN74ALS1245ADW equivalent, key selection criteria include its ±12 mA output drive, 13 ns max propagation delay (A→B/B→A), 25 ns max enable/disable timing, 0°C to 70°C temperature range, and compatibility with ALS logic families in space-constrained PCB layouts.
Technical Context
This device implements dual 8-bit bidirectional data paths controlled by a single direction (DIR) input and a common output-enable (OE) signal. Its TTL-compatible inputs accept 0.8 V low and 2.0 V high thresholds, while outputs deliver VOH ≥ 2.4 V at –0.4 mA and VOL ≤ 0.4 V at 8 mA load - meeting standard ALS voltage specifications.
The SN74ALS1245ADW uses open-collector–compatible totem-pole outputs with 3-state capability, enabling bus sharing without contention. Its switching characteristics are specified under CL = 50 pF, R1 = R2 = 500 Ω, and operate across the full recommended supply (4.5–5.5 V) and temperature (0°C to 70°C) ranges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage (VCC) | 4.5 V to 5.5 V - ensures stable operation with standard +5 V rail tolerances in industrial logic systems. |
| Propagation Delay (tPLH/tPHL) | 2 ns (min) to 13 ns (max) - enables reliable 75+ MHz bus handshaking in synchronous peripheral interfaces. |
| Output Drive (IOL/IOH) | 8 mA sink / –12 mA source - sufficient to drive 10+ ALS loads or terminate short stubs on parallel buses. |
| Enable/Disable Time (tPZL/tPHZ) | 8 ns (min) to 25 ns (max) - supports rapid bus arbitration and dynamic reconfiguration in multi-master systems. |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded controllers, test equipment, and legacy computing platforms. |
| Input Thresholds (VIH/VIL) | VIH ≥ 2.0 V, VIL ≤ 0.8 V - guarantees noise margin >400 mV against TTL/ALS logic families in mixed-signal environments. |
Pinout & Package
SN74ALS1245ADW is housed in a 20-pin plastic small-outline integrated circuit (SOIC) package (DW), 7.5 mm wide, with 0.65 mm lead pitch and gull-wing surface-mount terminals.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | DIR | Direction control: LOW enables B→A transfer; HIGH enables A→B transfer - determines data flow polarity. |
| 2–9 | A1–A8 | Port A data lines - connect to microprocessor address/data bus or local controller side. |
| 10 | GND | Ground reference - must be low-impedance connection to minimize ground bounce during 3-state transitions. |
| 11–18 | B1–B8 | Port B data lines - interface to peripheral bus, memory module, or expansion slot side. |
| 19 | OE | Output enable: LOW activates transceiver; HIGH places all A/B outputs in high-impedance state - isolates buses. |
| 20 | VCC | +5 V supply - requires local 0.1 µF ceramic decoupling adjacent to pin for transient current handling. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional 8-bit data path | Single DIR pin controls full A↔B data routing - eliminates need for dual unidirectional transceivers and reduces component count. |
| 3-state outputs with fast enable/disable | 25 ns max tPZH/tPLZ - enables time-critical bus sharing in real-time control loops without hold-time violations. |
| ALS-family compatibility | Matches SN74ALS245 timing and drive strength - allows drop-in replacement in existing ALS-based designs with no timing recalculations. |
| Low-power TTL logic | ICC ≤ 36 mA (all outputs low) - reduces thermal load in dense backplane modules compared to standard LS variants. |
| SOIC (DW) packaging | 20-pin surface-mount footprint - supports automated assembly and higher board density than through-hole DIP alternatives. |
Applications
| Industrial Backplane Interface | Legacy Microprocessor Expansion |
|---|---|
|
Use Scenario: Interfacing a Z80 or 8086 CPU bus to modular I/O cards in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: Bidirectional data bridge between CPU address/data bus (A-side) and peripheral card bus (B-side), synchronized to clocked control signals. Use Value: Enables hot-swappable I/O modules using DIR and OE to prevent bus contention during insertion/removal - critical for maintenance uptime. |
Use Scenario: Adding external RAM or EPROM to vintage computer motherboards where bus loading exceeds native driver capability. IC Role / Device Role / Timing Role: Bus buffer and level translator between MPU data bus and memory chip data pins, driven by MEMR/MEMW strobes. Use Value: Provides 8 mA sink current per line - sustains signal integrity across 15 cm traces on double-sided PCBs without added termination. |
| Test Equipment Data Acquisition | Avionics Maintenance Interface |
|
Use Scenario: Isolating DUT (device under test) digital I/O from automated test system controller during functional verification. IC Role / Device Role / Timing Role: Controlled isolation gate: OE disables transceiver during test setup; DIR selects stimulus (A→B) or response (B→A) mode. Use Value: 25 ns disable time ensures clean bus release before next test vector - prevents metastability in boundary-scan chains. |
Use Scenario: Adapting ground-support equipment to legacy aircraft avionics busses (e.g., MIL-STD-1553 auxiliary ports). IC Role / Device Role / Timing Role: Protocol-agnostic physical layer repeater between maintenance laptop UART-to-bus converter and aircraft subsystem data lines. Use Value: ALS logic family compatibility ensures correct voltage thresholds for 1553-compatible discrete-level translators - avoids false framing errors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bidirectional bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS245N | Same ALS family, identical pinout and DC specs, but lacks DIR-controlled bidirectionality - requires separate A→B and B→A devices. | Requires two ICs and additional control logic to replicate SN74ALS1245ADW's single-wire direction control. | Choose only if redesigning for simplified control architecture where DIR signal routing is impractical. |
| SN74LS1245N | LS-family version: higher ICC (45 mA), slower propagation (20 ns max), and lower noise immunity (VIH = 2.0 V same, but VIL = 0.8 V vs. LS's 0.8 V - identical threshold but weaker drive). | Compatible in static logic but may fail timing closure in high-speed backplanes due to 7 ns longer tPHL/tPLH. | Acceptable for low-frequency (<5 MHz) upgrades of LS-based systems where power budget allows +10 mA per device. |
Compared with SN74ALS245N and SN74LS1245N, the SN74ALS1245ADW delivers integrated bidirectional control in one SOIC package with superior speed-power trade-off - reducing board area by 35% and enabling tighter timing margins in legacy industrial bus architectures.
Availability
SN74ALS1245ADW is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy microprocessor expansions, test equipment data acquisition, and avionics maintenance interfaces requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS1245ADW 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 SN74ALS1245ADW belongs to TI's legacy ALS logic product line, engineered for high-speed, low-power TTL-compatible bus interfacing in mission-critical industrial and defense systems requiring long-lifecycle support.
FAQ
What is the maximum operating temperature range for the SN74ALS1245ADW?
The SN74ALS1245ADW is characterized for operation from 0°C to 70°C - this commercial-grade temperature specification aligns with standard industrial ambient conditions and excludes extended military or automotive extremes. The SN54ALS1245A variant supports –55°C to 125°C, but SN74ALS1245ADW does not.
Does the SN74ALS1245ADW support true bidirectional data flow on the same pins?
Yes - the SN74ALS1245ADW provides true bidirectional data transfer using shared A1–A8 and B1–B8 pins. Direction is controlled solely by the DIR input: when DIR = LOW, data flows B→A; when DIR = HIGH, data flows A→B. No external bus switches or multiplexers are required.
Can the SN74ALS1245ADW be used as a direct replacement for SN74ALS245N in existing designs?
No - the SN74ALS1245ADW is not a pin-compatible or functional replacement for SN74ALS245N. While both are ALS octal transceivers, SN74ALS245N is unidirectional (A→B only) and lacks DIR control. Replacing it requires redesigning control logic and verifying timing with the bidirectional path.
What is the recommended decoupling for SN74ALS1245ADW?
A 0.1 µF ceramic capacitor placed as close as possible to the VCC (pin 20) and GND (pin 10) terminals is required for stable operation. This minimizes supply rail disturbance during simultaneous 3-state transitions across all eight outputs - especially critical in high-density SOIC layouts.
Is the SN74ALS1245ADW RoHS compliant?
Yes - the SN74ALS1245ADW (DW package) carries NIPDAU lead finish and is RoHS compliant per TI's official packaging addendum. It meets EU Directive 2011/65/EU requirements and contains no lead, mercury, cadmium, hexavalent chromium, PBB, or PBDE above threshold limits.
SN74ALS1245ADW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Logic Type:
- Transceiver, Non-Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 15mA, 16mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74ALS1245ADW FAQ
1.How can I place an order for SN74ALS1245ADW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS1245ADW 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 SN74ALS1245ADW reliable?
The price and inventory of SN74ALS1245ADW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS1245ADW is usually 5 days.
3.What payment methods are accepted for SN74ALS1245ADW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS1245ADW transactions.
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4.How is shipping managed for SN74ALS1245ADW?
SN74ALS1245ADW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS1245ADW 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 SN74ALS1245ADW?
For technical support, including SN74ALS1245ADW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS1245ADW requirements.
6.How does Aetrix verify that SN74ALS1245ADW is sourced from the original manufacturer or authorized distributors?
All SN74ALS1245ADW 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 SN74ALS1245ADW meets industry standards.
7.What is the process for return or replacement of SN74ALS1245ADW?
All SN74ALS1245ADW units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS1245ADW, 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 SN74ALS1245ADW part is unused and in its original packaging.
Return procedure for SN74ALS1245ADW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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