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Texas Instruments SN74ALS245A-1NSR
- Part No.:
- SN74ALS245A-1NSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74ALS245A-1NSR.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,997
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Product details
Overview
SN74ALS245A-1NSR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in TTL-compatible systems. It operates from 4.5 V to 5.5 V, delivers max propagation delay of 5.5 ns at 5 V, supports 48 mA low-level output current (IOL), and features pnp input structure to reduce DC loading. It is used in industrial backplane interfaces and legacy microprocessor data bus isolation.
For engineers reviewing the SN74ALS245A-1NSR datasheet, SN74ALS245A-1NSR pinout, SN74ALS245A-1NSR application, or SN74ALS245A-1NSR equivalent, key selection criteria include its -1 version's enhanced 48 mA IOL rating, SOP-20 (NS) package thermal performance (θJA = 60°C/W), 3-state control timing (tPZH/tPLZ ≤ 20 ns), and compatibility with 5-V TTL logic families.
Technical Context
The SN74ALS245A-1NSR implements dual-control 3-state logic: DIR selects data direction (A→B or B→A), while OE enables/disables all outputs. Its pnp-input architecture lowers input current draw versus standard TTL, reducing bus loading on driving sources.
It uses bipolar ALS (Advanced Low-Power Schottky) technology, delivering higher speed than standard LS logic while maintaining TTL voltage thresholds (VIH = 2 V, VIL = 0.8 V) and compatible output drive (VOH ≥ 2.4 V at IOH = –12 mA, VOL ≤ 0.35 V at IOL = 48 mA).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - Ensures robust operation across industrial 5-V supply tolerances. |
| Max tpd | 5.5 ns at 5 V - Enables reliable timing in high-speed 5-V bus systems up to ~180 MHz toggle rate. |
| IOL (–1 version) | 48 mA - Supports direct drive of heavy capacitive loads or multiple TTL inputs without external buffers. |
| VIH / VIL | 2.0 V / 0.8 V - Fully compatible with standard TTL logic thresholds for seamless integration. |
| θJA | 60°C/W (NS package) - Defines thermal derating limit for continuous operation at ambient up to 70°C. |
| 3-State Enable Time | tPZH ≤ 20 ns - Guarantees fast bus release during dynamic arbitration or multiplexing. |
Pinout & Package
SOP-20 (NS) package: 20-pin small-outline plastic package, 0.65 mm pitch, 7.4 mm × 5.3 mm body, 2.0 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A1–A8 inputs/outputs | One side of bidirectional data bus; connected to source system (e.g., CPU address/data lines). |
| 11, 12, 13, 14, 15, 16, 17, 18 | B1–B8 inputs/outputs | Other side of bidirectional data bus; connected to peripheral or memory subsystem. |
| 9 | GND | Ground reference for all internal circuitry and I/O switching. |
| 10 | VCC | Positive supply (4.5–5.5 V); powers internal logic and output drivers. |
| 19 | DIR | Direction control: LOW = B→A, HIGH = A→B; synchronous with data edges. |
| 20 | OE | Output enable: LOW = active (3-state disabled), HIGH = outputs high-impedance. |
Key Features
| Feature | Design Value |
|---|---|
| Enhanced drive strength | 48 mA IOL (–1 version) enables direct interface to 10+ standard TTL loads without fanout buffers. |
| pnp input structure | Reduces input current to ≤0.1 mA, minimizing DC loading on upstream drivers and improving noise margin. |
| Fast 3-state switching | tPHZ/tPLZ ≤ 10 ns ensures minimal bus contention during direction or enable transitions. |
| TTL-compatible thresholds | VIH = 2.0 V and VIL = 0.8 V guarantee interoperability with legacy 5-V microcontrollers and peripherals. |
Applications
| Industrial Backplane Interface | Legacy Microprocessor Bus Isolation |
|---|---|
Use Scenario: Isolating CPU data/address bus from expansion slot peripherals in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional bus transceiver enabling controlled data flow between MPU and I/O modules under DIR/OE arbitration. Use Value: Prevents bus contention during hot-swap or module reset via precise 3-state timing (tPZH ≤ 20 ns) and 48 mA drive for long trace runs. | Use Scenario: Buffering Z80 or 8086 data bus between processor and memory-mapped peripherals. IC Role / Device Role / Timing Role: Octal transceiver providing direction-controlled data path with TTL-compatible voltage levels and sub-6 ns propagation. Use Value: Maintains signal integrity across 15 cm PCB traces using pnp-input low loading and 5.5 ns tpd at 5 V. |
| Test Equipment Data Path Switching | Automated Test Fixture Signal Routing |
Use Scenario: Dynamically reconfiguring signal paths between DUT ports and measurement instruments in ATE systems. IC Role / Device Role / Timing Role: 3-state-enabled bus switch allowing software-directed routing of 8-bit parallel signals. Use Value: Enables glitch-free path reconfiguration with tPLZ ≤ 15 ns and guaranteed high-impedance isolation (IOZ ≤ ±10 µA). | Use Scenario: Multiplexing sensor data streams from multiple analog front-ends into a single ADC interface. IC Role / Device Role / Timing Role: Direction-controlled transceiver synchronizing burst-mode sensor reads onto shared data bus. Use Value: Supports deterministic timing with 5.5 ns tpd and 0.35 V VOL at 48 mA, ensuring clean logic levels despite varying load capacitance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS245ANSR | Standard version: IOL = 24 mA (not 48 mA); identical pinout, timing, and package. | Lower drive capability limits use in high-capacitance or multi-load bus segments. | Select when 24 mA IOL suffices and cost optimization is prioritized over margin. |
| SN74AS245NSR | Faster: tpd = 7.5 ns max; higher ICC (95 mA vs. 60 mA); AS logic family, same VCC/VIL/VIH. | Higher power consumption and stricter layout requirements due to faster edge rates. | Choose for maximum speed where power and noise budgets allow; not drop-in due to different AC characteristics. |
Compared with SN74ALS245ANSR and SN74AS245NSR, the SN74ALS245A-1NSR uniquely balances enhanced 48 mA drive, proven ALS noise immunity, and low static power-making it optimal for industrial bus interfaces requiring reliability over raw speed.
Availability
SN74ALS245A-1NSR is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy microprocessor bus isolation, and automated test equipment requiring stable component supply across extended product lifecycles.
Supply support for SN74ALS245A-1NSR 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 specializing in analog, embedded processing, and logic solutions with decades of legacy logic product support.
The SN74ALS245A-1NSR belongs to TI's Advanced Low-Power Schottky (ALS) logic family, engineered for high-speed, low-power 5-V TTL system interfacing in industrial and test equipment applications.
FAQ
What is the maximum recommended low-level output current for SN74ALS245A-1NSR?
The SN74ALS245A-1NSR is the "–1" version, specifying a maximum recommended IOL of 48 mA when VCC is between 4.75 V and 5.25 V. This is double the 24 mA rating of the standard SN74ALS245A, enabling stronger drive capability for heavily loaded buses. The 48 mA value is explicitly defined in the Recommended Operating Conditions table and confirmed in Electrical Characteristics under IOL test conditions.
Which package type does SN74ALS245A-1NSR use, and what are its key mechanical dimensions?
SN74ALS245A-1NSR uses the SOP-20 (NS) package: 20-pin small-outline plastic package with 0.65 mm lead pitch, 7.4 mm × 5.3 mm body size, and 2.0 mm maximum height. Its thermal impedance is θJA = 60°C/W, and it complies with JEDEC MO-150. The part marking is "ALS245A-1", and it ships in tape-and-reel format (2000 units per reel).
How does the DIR and OE control logic function in SN74ALS245A-1NSR?
In SN74ALS245A-1NSR, DIR determines data direction: DIR = LOW enables B→A transfer; DIR = HIGH enables A→B transfer. OE controls 3-state output enable: OE = LOW activates outputs; OE = HIGH places all A and B terminals in high-impedance state. Both controls operate asynchronously, and the device remains isolated when OE is HIGH regardless of DIR state, as confirmed in the Function Table and Logic Diagram.
Is SN74ALS245A-1NSR compatible with standard TTL logic families?
Yes, SN74ALS245A-1NSR is fully compatible with standard TTL. Its input thresholds (VIH = 2.0 V, VIL = 0.8 V) and output voltage levels (VOH ≥ 2.4 V at –12 mA, VOL ≤ 0.35 V at 48 mA) meet TTL specifications. The pnp-input structure also ensures low input current (<0.1 mA), preserving TTL fanout capability and noise margins in mixed-logic systems.
What is the typical propagation delay of SN74ALS245A-1NSR at 5 V?
The typical propagation delay (tpd) of SN74ALS245A-1NSR is 5.5 ns at VCC = 5 V, CL = 50 pF, and TA = 25°C, as specified in the Absolute Maximum Ratings and Switching Characteristics tables. This value applies to both A→B and B→A directions and reflects the maximum guaranteed delay under worst-case conditions across the commercial temperature range (0°C to 70°C).
SN74ALS245A-1NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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, 24mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74ALS245A-1NSR FAQ
1.How can I place an order for SN74ALS245A-1NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS245A-1NSR 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 SN74ALS245A-1NSR reliable?
The price and inventory of SN74ALS245A-1NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS245A-1NSR is usually 5 days.
3.What payment methods are accepted for SN74ALS245A-1NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS245A-1NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS245A-1NSR?
SN74ALS245A-1NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS245A-1NSR 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 SN74ALS245A-1NSR?
For technical support, including SN74ALS245A-1NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS245A-1NSR requirements.
6.How does Aetrix verify that SN74ALS245A-1NSR is sourced from the original manufacturer or authorized distributors?
All SN74ALS245A-1NSR 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 SN74ALS245A-1NSR meets industry standards.
7.What is the process for return or replacement of SN74ALS245A-1NSR?
All SN74ALS245A-1NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS245A-1NSR, 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 SN74ALS245A-1NSR part is unused and in its original packaging.
Return procedure for SN74ALS245A-1NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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