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Texas Instruments SN74ALS245ADWG4
- Part No.:
- SN74ALS245ADWG4
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS245ADWG4.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:950
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Product details
Overview
SN74ALS245ADWG4 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 12 mA low-level output current (IOL), and features pnp input structure to reduce DC loading - used in industrial backplane interfaces and legacy microprocessor data bus isolation.
For engineers reviewing the SN74ALS245ADWG4 datasheet, SN74ALS245ADWG4 pinout, SN74ALS245ADWG4 application, or SN74ALS245ADWG4 equivalent, key selection criteria include direction-control logic behavior, 3-state enable timing (tPZH/tPLZ), VCC tolerance, thermal impedance (58°C/W for DW package), and compatibility with 5-V TTL signal levels in bus-hold or hot-swap-adjacent designs.
Technical Context
This device implements dual-directional bus communication via a single DIR input that determines data flow direction (A→B when DIR = HIGH, B→A when DIR = LOW). The OE input independently controls 3-state output enable/disable with guaranteed isolation when high, supporting bus contention avoidance in multi-driver systems.
Its ALS (Advanced Low-Power Schottky) logic family provides improved speed-power trade-off over standard LS, with pnp input stages reducing input current draw and enabling direct connection to open-collector or high-impedance nodes without pull-up resistors.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - ensures robust operation across noisy 5-V supply rails common in industrial control and instrumentation. |
| Max tpd | 5.5 ns at VCC = 5 V - enables reliable timing in 80–100 MHz bus cycles with margin for trace delays. |
| IOL (min) | 12 mA - drives standard TTL loads directly without external buffers in point-to-point or lightly loaded bus segments. |
| VOH (min) | 2.4 V at IOH = –12 mA - maintains valid HIGH logic level under full load, compatible with 74LS/ALS input thresholds. |
| VOL (max) | 0.4 V at IOL = 12 mA - guarantees solid LOW recognition by downstream TTL receivers even at worst-case temperature. |
| θJA | 58°C/W (DW package) - defines thermal derating limit for continuous operation at ambient up to 70°C with no forced airflow. |
| Operating Temp | 0°C to 70°C - qualified for commercial-grade embedded systems including test equipment and peripheral controllers. |
Pinout & Package
SN74ALS245ADWG4 uses a 20-pin SOIC (DW) package, 7.5 mm × 12.8 mm body, 1.27 mm lead pitch, 2.65 mm max height, RoHS-compliant NiPdAu lead finish, and MSL Level-1 rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DIR (Pin 2) | Direction Control Input | Logic HIGH enables A→B data flow; LOW enables B→A - critical for synchronous bus arbitration in master-slave architectures. |
| OE (Pin 19) | Output Enable Input | Active LOW - asserts 3-state when HIGH, isolating both A and B ports electrically to prevent bus contention. |
| A1–A8 (Pins 1,3–6,14–16) | Port A Data I/O | Bidirectional TTL-compatible inputs/outputs tied to local subsystem bus; require external pull-ups only if floating. |
| B1–B8 (Pins 18,17,13,12,11,10,9,7) | Port B Data I/O | Matched 8-bit counterpart to Port A; pin-mapped for straight PCB routing with minimal layer crossover. |
| VCC (Pin 20) | Power Supply | Must be decoupled locally with ≥0.1 µF ceramic capacitor to suppress switching noise coupling into adjacent channels. |
| GND (Pin 10) | Ground Reference | Common return for all I/O and supply currents - shared ground plane essential to minimize ground bounce in multi-transceiver layouts. |
Key Features
| Feature | Design Value |
|---|---|
| 3-State Outputs | Enables true bus sharing across multiple drivers without external logic or arbitration circuitry. |
| pnp Input Structure | Reduces DC input loading to ≤0.1 mA per control input - eliminates need for pull-up resistors on DIR/OE in most configurations. |
| ALS Logic Family | Combines 5.5 ns speed with ~36 mA typical ICC (outputs low) - lower power than AS while retaining high drive capability. |
| Wide VCC Margin | 4.5–5.5 V operation accommodates ±5% supply variation and brown-out conditions without functional loss. |
| TTL-Compatible Thresholds | VIH = 2.0 V / VIL = 0.8 V ensures interoperability with legacy 74LS, 74F, and microcontroller GPIOs. |
Applications
| Industrial Backplane Interface | Microprocessor System Expansion |
|---|---|
Use Scenario: Isolating CPU address/data bus from peripheral expansion slots in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing data flow between MPU and add-on I/O modules during read/write cycles. Use Value: Prevents bus contention during slot insertion/removal and supports hot-swap-safe enable sequencing via OE control. | Use Scenario: Connecting Z80 or 8086-based system buses to memory-mapped peripherals like UARTs or ADCs. IC Role / Device Role / Timing Role: Direction-controlled data bridge synchronizing 8-bit parallel transfers between processor and peripheral registers. Use Value: Eliminates need for discrete direction logic and reduces PCB real estate versus dual unidirectional buffers. |
| Legacy Test Equipment Bus | Automated Manufacturing Fixture |
Use Scenario: Routing GPIB or IEEE-488 bus signals through modular instrument chassis with configurable signal paths. IC Role / Device Role / Timing Role: Reconfigurable bus coupler enabling dynamic reassignment of DIO lines across test head modules. Use Value: Enables software-defined bus topology changes without hardware modification or jumpering. | Use Scenario: Interfacing PLC outputs to fixture-mounted solenoid drivers and sensor inputs in SMT board testers. IC Role / Device Role / Timing Role: Level-shifting and isolation buffer between 5-V controller logic and 24-V industrial I/O subsystems. Use Value: Provides galvanic separation via external optocouplers while preserving TTL timing integrity on the logic side. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AS245DWR | Faster tpd (7.5 ns max), higher IOL (48 mA), AS family - increased power consumption (~97 mA ICC). | Suitable for high-speed backplanes requiring tighter timing margins but less tolerant of supply noise. | Select when propagation delay < 8 ns is mandatory and power budget allows +60 mA typical ICC increase. |
| SN74LS245N | Slower tpd (22 ns max), lower drive (IOL = 24 mA), LS family - lower cost and wider temp range (-55°C to 125°C). | Preferred for cost-sensitive, non-critical timing applications where 5-V TTL compatibility remains essential. | Choose for legacy replacement where speed is secondary and extended temperature qualification is required. |
Compared with SN74AS245DWR and SN74LS245N, SN74ALS245ADWG4 delivers optimal balance of speed (5.5 ns), power efficiency (~36 mA ICC), and noise immunity - making it ideal for commercial-grade embedded systems where reliability and moderate performance coexist.
Availability
SN74ALS245ADWG4 is available at Aetrix Electronics and suitable for industrial backplane interfaces, microprocessor system expansion, legacy test equipment buses, and automated manufacturing fixtures requiring stable component supply across long production lifecycles.
Supply support for SN74ALS245ADWG4 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 over 90 years of innovation in industrial, automotive, and communications markets.
SN74ALS245ADWG4 belongs to TI's legacy TTL logic portfolio, engineered specifically for robust 5-V bus interfacing in commercial-grade systems where speed, power, and compatibility must coexist without compromise.
FAQ
What is the maximum propagation delay of the SN74ALS245ADWG4 at 5 V?
The SN74ALS245ADWG4 has a maximum propagation delay (tpd) of 5.5 ns when operating at VCC = 5 V with CL = 50 pF and R1/R2 = 500 Ω, as specified in the switching characteristics table. This value applies to both A→B and B→A data paths and represents worst-case timing under recommended operating conditions.
Does the SN74ALS245ADWG4 support bidirectional data flow without external logic?
Yes, the SN74ALS245ADWG4 supports fully bidirectional data flow using its dedicated DIR (direction) input. When DIR = HIGH, data passes from Port A to Port B; when DIR = LOW, data flows from Port B to Port A - eliminating need for external multiplexers or dual unidirectional buffers in bus interface designs.
What is the function of the OE pin on the SN74ALS245ADWG4?
The OE (output enable) pin on the SN74ALS245ADWG4 is an active-LOW control that places all A and B port outputs into high-impedance (3-state) mode when asserted HIGH. This enables electrical isolation of both buses during idle periods or arbitration events, preventing signal contention in multi-driver systems.
Can the SN74ALS245ADWG4 operate with a 4.75-V supply?
Yes, the SN74ALS245ADWG4 is fully specified to operate across 4.5 V to 5.5 V, so a 4.75-V supply falls within its recommended operating range. All electrical characteristics - including VOH, VOL, and tpd - remain guaranteed at this voltage, provided ambient temperature stays within 0°C to 70°C.
Is the SN74ALS245ADWG4 pin-compatible with the SN74AS245DWR?
Yes, the SN74ALS245ADWG4 and SN74AS245DWR share identical 20-pin SOIC (DW) packaging, pinout, and terminal functions - including DIR, OE, A1–A8, B1–B8, VCC, and GND assignments. However, differences in timing, drive strength, and power consumption require validation in the target application before substitution.
SN74ALS245ADWG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- 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-SOIC
SN74ALS245ADWG4 FAQ
1.How can I place an order for SN74ALS245ADWG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS245ADWG4 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 SN74ALS245ADWG4 reliable?
The price and inventory of SN74ALS245ADWG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS245ADWG4 is usually 5 days.
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SN74ALS245ADWG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS245ADWG4 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 SN74ALS245ADWG4?
For technical support, including SN74ALS245ADWG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS245ADWG4 requirements.
6.How does Aetrix verify that SN74ALS245ADWG4 is sourced from the original manufacturer or authorized distributors?
All SN74ALS245ADWG4 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 SN74ALS245ADWG4 meets industry standards.
7.What is the process for return or replacement of SN74ALS245ADWG4?
All SN74ALS245ADWG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS245ADWG4, 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 SN74ALS245ADWG4 part is unused and in its original packaging.
Return procedure for SN74ALS245ADWG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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