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Texas Instruments SN74ALS245A-1DWRG4
- Part No.:
- SN74ALS245A-1DWRG4
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ALS245A-1DWRG4.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,117
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Product details
Overview
SN74ALS245A-1DWRG4 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 a maximum 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 - used in industrial control backplanes and legacy computing bus interfaces.
For engineers reviewing the SN74ALS245A-1DWRG4 datasheet, SN74ALS245A-1DWRG4 pinout, SN74ALS245A-1DWRG4 application, or SN74ALS245A-1DWRG4 equivalent, key selection criteria include its -1 version's enhanced 48 mA IOL drive capability, SOIC-DW package thermal performance (θJA = 58°C/W), direction-control (DIR) and output-enable (OE) logic interface behavior, and compatibility with 5-V TTL bus loading requirements.
Technical Context
This device implements dual-directional 8-bit data routing via DIR-controlled signal flow (A→B or B→A) and OE-gated 3-state output isolation. Its pnp input stage minimizes input current draw, reducing bus loading compared to standard TTL inputs.
Switching timing is characterized under CL = 50 pF, R1/R2 = 500 Ω, and includes tPLH/tPHL ≤ 10 ns (A↔B), tPZH/tPZL ≤ 20 ns (OE→output enable/disable), and tPHZ/tPLZ ≤ 10 ns (OE→output high/low transition), ensuring deterministic bus arbitration in synchronous and asynchronous systems.
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 without level-shifting. |
| Max tpd | 5.5 ns at VCC = 5 V - enables high-speed bus handshaking in legacy microprocessor data paths. |
| IOL (–1 version) | 48 mA - drives heavy TTL loads (e.g., ≥10 LS-TTL inputs) without external buffers. |
| VOH / VOL | VOH ≥ 2.4 V (IOH = –12 mA); VOL ≤ 0.4 V (IOL = 48 mA) - meets TTL output voltage thresholds for reliable logic-level interfacing. |
| Input Structure | pnp-based inputs - reduces DC input current to ≤0.1 mA, minimizing bus loading and power dissipation. |
| Operating Temp | 0°C to 70°C - qualified for commercial-grade embedded and industrial control applications. |
| Package | SOIC-DW, 20-pin - surface-mount footprint compatible with automated assembly and IPC-7351 land patterns. |
Pinout & Package
SN74ALS245A-1DWRG4 uses a 20-pin SOIC-DW package (7.5 mm × 12.8 mm, 1.27 mm pitch, max height 2.65 mm) with standard JEDEC MS-013 outline and RoHS-compliant NiPdAu lead finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A1–A8 | Input/output port A - bidirectional data lines connected to one bus segment; driven high/low or placed in high-impedance state per DIR/OE. |
| 11, 12, 13, 14, 15, 16, 17, 18 | B1–B8 | Input/output port B - bidirectional data lines connected to second bus segment; direction relative to A determined by DIR. |
| 9 | GND | Ground reference - common return path for all internal logic and I/O currents. |
| 10 | VCC | Power supply - supplies core logic and output drivers; requires local 0.1 µF bypass capacitor. |
| 19 | DIR | Direction control - low = B→A data flow; high = A→B data flow; TTL-compatible input threshold (VIL ≤ 0.8 V, VIH ≥ 2 V). |
| 20 | OE | Output enable - low = outputs active; high = all A/B pins in 3-state (high-Z); enables bus isolation during arbitration. |
Key Features
| Feature | Design Value |
|---|---|
| Enhanced drive strength | 48 mA IOL (–1 version) - eliminates need for external bus drivers when interfacing with multiple LS-TTL loads. |
| Low DC input loading | pnp input structure limits II ≤ 0.1 mA - reduces cumulative bus capacitance and power consumption in multi-device configurations. |
| Fast 3-state switching | tPHZ/tPLZ ≤ 10 ns - minimizes bus contention window during direction or enable transitions. |
| Robust noise immunity | VIL = 0.8 V, VIH = 2.0 V - provides ≥0.4 V noise margin against TTL-level interference on control inputs. |
| Thermal performance | θJA = 58°C/W (DW package) - supports sustained operation at full drive in compact industrial PCB layouts. |
Applications
| Industrial Backplane Interface | Legacy Microprocessor Data Bus |
|---|---|
|
Use Scenario: Isolating and translating data between CPU and peripheral modules on a 5-V ISA-style backplane. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing A-bus (CPU side) ↔ B-bus (peripheral side) under DIR/OE control. Use Value: 48 mA IOL drives long traces and multiple TTL loads; 5.5 ns tpd maintains timing margins in 8-MHz bus cycles. |
Use Scenario: Interfacing Z80 or 8086 CPU data bus to memory-mapped I/O devices with independent address/data domains. IC Role / Device Role / Timing Role: Direction-controlled data bridge enabling CPU read/write to peripherals without bus contention. Use Value: pnp inputs reduce cumulative DC loading on shared data bus; 3-state isolation prevents signal corruption during DMA cycles. |
| Test Equipment Signal Routing | Programmable Logic Controller (PLC) I/O Expansion |
|
Use Scenario: Dynamically reconfiguring signal paths between DUT interface connectors and measurement instruments in ATE systems. IC Role / Device Role / Timing Role: Reversible data channel controlled by FPGA-generated DIR/OE signals for flexible test pattern routing. Use Value: Fast enable/disable (tPZH ≤ 20 ns) allows sub-100 ns bus reconfiguration; SOIC-DW package supports dense PCB layout. |
Use Scenario: Extending discrete I/O capacity between PLC main controller and remote I/O racks over parallel backplane wiring. IC Role / Device Role / Timing Role: Level-translating and load-driving interface between controller bus and ruggedized field I/O modules. Use Value: 48 mA drive sustains signal integrity over 30 cm ribbon cables; 0°C to 70°C rating matches industrial enclosure environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS245ADWR | Standard version (non–1); rated IOL = 24 mA (max), not 48 mA. | Lower drive capability limits use in high-fanout or long-trace scenarios where SN74ALS245A-1DWRG4 is specified. | Select SN74ALS245A-1DWRG4 when ≥48 mA sink current is required; use SN74ALS245ADWR only if fanout ≤ 5 LS-TTL loads. |
| SN74AS245DWR | AS-family variant; faster tpd (7.5 ns max), higher ICC (97 mA), higher IIL (–0.75 mA), no –1 version. | Higher speed suits tighter timing budgets but increases power and input loading; incompatible with ALS-level noise margins. | Choose SN74AS245DWR only when propagation delay < 8 ns is mandatory and system can accommodate +60% supply current and reduced noise immunity. |
Compared with SN74ALS245ADWR and SN74AS245DWR, SN74ALS245A-1DWRG4 uniquely balances 48 mA drive, 5.5 ns speed, and low-input-current pnp architecture - making it optimal for industrial backplanes requiring robust TTL interfacing without excessive power or noise sensitivity.
Availability
SN74ALS245A-1DWRG4 is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy microprocessor data buses, and programmable logic controller I/O expansion requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS245A-1DWRG4 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 delivering analog, embedded processing, and logic solutions with emphasis on reliability, longevity, and industrial-grade qualification.
SN74ALS245A-1DWRG4 belongs to TI's legacy TTL-compatible logic family, engineered specifically for robust 5-V bus interfacing in industrial control, test equipment, and retro-computing systems where compatibility and drive strength are critical.
FAQ
What is the maximum output sink current supported by SN74ALS245A-1DWRG4?
The SN74ALS245A-1DWRG4 supports a maximum low-level output current (IOL) of 48 mA when VCC is between 4.75 V and 5.25 V. This enhanced drive capability - specific to the "–1" version - allows direct interfacing with up to 10 LS-TTL inputs or long PCB traces without external buffering. Standard SN74ALS245A variants are limited to 24 mA IOL.
Does SN74ALS245A-1DWRG4 require external pull-up resistors on its A or B bus lines?
No, SN74ALS245A-1DWRG4 does not require external pull-up resistors on A or B I/O lines because its outputs are active-drive (totem-pole), not open-collector. However, unused control inputs (DIR and OE) must be externally held at VCC or GND per TI's SCBA004 guidance to prevent floating states that could cause increased ICC or undefined output behavior.
Can SN74ALS245A-1DWRG4 operate with a 3.3-V supply?
No, SN74ALS245A-1DWRG4 is specified only for 4.5 V to 5.5 V operation. Applying 3.3 V violates the recommended operating conditions and will result in non-functional outputs, degraded noise margins, and potential latch-up. For 3.3-V systems, consider TI's LVC or ALVC series transceivers instead.
What is the thermal resistance (θJA) of the SN74ALS245A-1DWRG4 in its SOIC-DW package?
The SN74ALS245A-1DWRG4 in the SOIC-DW package has a junction-to-ambient thermal resistance (θJA) of 58°C/W, as confirmed in the official TI datasheet SDAS272A. This value assumes standard JEDEC 2S2P board conditions and informs thermal design for continuous 48 mA output loading in enclosed industrial enclosures.
Is SN74ALS245A-1DWRG4 pin-compatible with SN74ALS245ADWR?
Yes, SN74ALS245A-1DWRG4 is pin-compatible with SN74ALS245ADWR - both use identical SOIC-DW-20 packages with identical pinout, footprint, and solder mask requirements. The only functional difference is the guaranteed 48 mA IOL rating in the –1 version versus 24 mA in the standard version; no PCB redesign is needed for drop-in replacement where drive strength permits.
SN74ALS245A-1DWRG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- 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
SN74ALS245A-1DWRG4 FAQ
1.How can I place an order for SN74ALS245A-1DWRG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS245A-1DWRG4 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-1DWRG4 reliable?
The price and inventory of SN74ALS245A-1DWRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS245A-1DWRG4 is usually 5 days.
3.What payment methods are accepted for SN74ALS245A-1DWRG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS245A-1DWRG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS245A-1DWRG4?
SN74ALS245A-1DWRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS245A-1DWRG4 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-1DWRG4?
For technical support, including SN74ALS245A-1DWRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS245A-1DWRG4 requirements.
6.How does Aetrix verify that SN74ALS245A-1DWRG4 is sourced from the original manufacturer or authorized distributors?
All SN74ALS245A-1DWRG4 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-1DWRG4 meets industry standards.
7.What is the process for return or replacement of SN74ALS245A-1DWRG4?
All SN74ALS245A-1DWRG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS245A-1DWRG4, 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-1DWRG4 part is unused and in its original packaging.
Return procedure for SN74ALS245A-1DWRG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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