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Texas Instruments SN74ALS245ADBR
- Part No.:
- SN74ALS245ADBR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74ALS245ADBR.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,623
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Product details
Overview
SN74ALS245ADBR 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 10 ns at 5 V, supports ±24 mA output drive, and features pnp input structure to reduce DC loading. It is used in industrial backplane interfaces and legacy microprocessor data bus expansion.
For engineers reviewing the SN74ALS245ADBR datasheet, SN74ALS245ADBR pinout, SN74ALS245ADBR application, or SN74ALS245ADBR equivalent, key selection criteria include its SSOP-20 package footprint, 3-state bus isolation capability, direction-control (DIR) and output-enable (OE) logic interface, and compatibility with ALS logic family timing and voltage thresholds.
Technical Context
This device implements dual 8-bit bidirectional data paths controlled by separate DIR (direction) and OE (output enable) inputs. Data flows from A-to-B when DIR = HIGH and OE = LOW, or from B-to-A when DIR = LOW and OE = LOW; OE = HIGH forces all outputs into high-impedance state regardless of DIR.
The SN74ALS245ADBR uses bipolar ALS (Advanced Low-Power Schottky) technology, delivering faster switching than standard LS logic while maintaining TTL-compatible input thresholds (VIH = 2 V min, VIL = 0.8 V max) and output voltage levels (VOH = 2.4 V min at IOL = 24 mA, VOL = 0.4 V max).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - Ensures robust operation across industrial power supply tolerances and brown-out conditions. |
| Max Propagation Delay | 10 ns at VCC = 5 V - Enables reliable 100-MHz bus handshaking in synchronous peripheral interfaces. |
| IOL / IOH | ±24 mA - Drives standard TTL loads directly without external buffers; sufficient for 10-unit load fanout. |
| Input Thresholds | VIH = 2.0 V min, VIL = 0.8 V max - Guarantees noise immunity and interoperability with 5-V CMOS and TTL logic families. |
| 3-State Enable Time | tPZL = 20 ns max - Limits bus contention window during hot-swap or dynamic bus arbitration sequences. |
| Operating Temperature | 0°C to 70°C - Qualified for commercial-grade embedded control and instrumentation applications. |
| Package | SSOP-20 (DB), 7.5 mm × 5.6 mm - Provides compact surface-mount footprint with 0.65 mm lead pitch for high-density PCB layouts. |
Pinout & Package
SN74ALS245ADBR is housed in a 20-pin Small Outline Shrink Plastic (SSOP-20) package (drawing DB), measuring 7.5 mm × 5.6 mm with 0.65 mm lead pitch and maximum height of 2.0 mm. Pin 1 is located at the top-left corner with index area marking "G245A".
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (DIR) | Direction Control Input | Determines data flow direction: HIGH enables A→B, LOW enables B→A; referenced to GND/VCC. |
| 2–9 (A1–A8) | Port A I/O Terminals | Bidirectional data lines connected to source bus; internally buffered with pnp inputs to minimize DC loading. |
| 10 (GND) | Ground Reference | Primary signal return path; must be low-inductance connection to maintain noise margin and timing integrity. |
| 11 (VCC) | Power Supply | +5 V supply rail; requires local 0.1 µF ceramic decoupling capacitor placed within 5 mm of pin. |
| 12 (OE) | Output Enable Input | Active-LOW control: drives all A/B outputs to high-Z when HIGH; synchronizes bus release timing. |
| 13–20 (B1–B8) | Port B I/O Terminals | Bidirectional data lines connected to destination bus; electrically identical to A-side terminals. |
Key Features
| Feature | Design Value |
|---|---|
| ALS Logic Family | Combines Schottky-clamped bipolar transistors for 3× speed improvement over standard LS, with 1/3 power consumption. |
| pnp Input Structure | Reduces input current to ≤0.1 mA, enabling direct connection to high-impedance sources without pull-up/pull-down resistors. |
| 3-State Bus Isolation | Simultaneous high-Z on all 16 I/O pins eliminates bus contention during multi-master arbitration or power sequencing. |
| TTL-Compatible Interface | Meets JEDEC JESD7-A input/output voltage thresholds and drive strength, ensuring drop-in replacement for legacy 74LS245 designs. |
| SSOP-20 Packaging | Enables 40% board area reduction vs. PDIP-20 while supporting automated reflow assembly per IPC-J-STD-020 Level-1. |
Applications
| Industrial Backplane Interface | Microprocessor Data Bus Expansion |
|---|---|
Use Scenario: Interfacing multiple 8-bit peripheral modules (ADCs, DACs, GPIO expanders) to a central controller via shared parallel bus. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing data flow direction and isolating inactive modules using DIR and OE signals. Use Value: Eliminates need for discrete direction logic and bus buffers; supports up to 10 TTL loads per line with guaranteed 10 ns timing margins. | Use Scenario: Extending the data bus of an 8051 or Z80-based system to support additional memory or I/O chips. IC Role / Device Role / Timing Role: Level-shifting and bus-driving transceiver that matches ALS timing characteristics required by vintage CPU bus protocols. Use Value: Maintains strict setup/hold timing compliance under 5 V supply variation; pnp inputs prevent excessive current draw from CPU address/data lines. |
| Legacy Test Equipment Control | Programmable Logic Interface |
Use Scenario: Connecting FPGA or CPLD I/O banks to legacy instrument control buses (e.g., GPIB auxiliary lines or IEEE-488 data lines). IC Role / Device Role / Timing Role: Voltage- and timing-compliant interface translating between modern programmable logic I/O and 5-V TTL bus standards. Use Value: Provides deterministic 3-state control synchronized to FPGA clock domain; avoids metastability during bus handoff transitions. | Use Scenario: Implementing configurable data routing in modular digital signal processing chassis with hot-swappable cards. IC Role / Device Role / Timing Role: Reconfigurable bus coupler enabling dynamic A↔B path selection under microcontroller supervision. Use Value: DIR and OE inputs allow real-time bus topology reconfiguration without power cycling; SSOP package supports dense card-edge layout. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ALS245AN | Same ALS logic, identical electrical specs, but in 20-pin PDIP package (13.97 mm width, through-hole mount). | Suitable for prototyping, manual assembly, or legacy through-hole PCBs; lacks SSOP's thermal and density advantages. | Select SN74ALS245AN only when through-hole mounting or breadboard evaluation is required. |
| SN74AS245NSR | AS-family variant: faster tPLH/tPHL (7.5 ns max), higher IOL (64 mA), but increased ICC (97 mA active) and reduced noise margin (VIH = 2.0 V, VIL = 0.8 V same). | Better for high-speed bus segments requiring sub-10 ns timing; not recommended where power budget or EMI sensitivity is critical. | Choose SN74AS245NSR only when propagation delay is the dominant constraint and supply current >95 mA is acceptable. |
Compared with SN74ALS245AN and SN74AS245NSR, the SN74ALS245ADBR offers optimal balance of speed (10 ns), power (38 mA ICC disabled), and board space (SSOP-20), making it ideal for volume-manufactured commercial embedded systems where thermal profile and assembly automation matter.
Availability
SN74ALS245ADBR is available at Aetrix Electronics and suitable for industrial backplane interfaces, microprocessor data bus expansion, legacy test equipment control, and programmable logic interface applications requiring stable component supply and long-term production continuity.
Supply support for SN74ALS245ADBR 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 50 years of innovation in industrial, automotive, and communications markets.
The SN74ALS245ADBR belongs to TI's legacy TTL-compatible logic portfolio, engineered specifically for backward-compatible bus interfacing in commercial-grade systems where reliability, timing predictability, and second-source availability are essential.
FAQ
What is the maximum operating temperature range for the SN74ALS245ADBR?
The SN74ALS245ADBR is rated for operation from 0°C to 70°C, conforming to commercial-grade specifications. This range supports deployment in office equipment, industrial controllers, and consumer electronics where ambient temperatures remain within standard indoor environments. It does not meet extended or military temperature requirements (–55°C to 125°C), which apply only to SN54ALS245A variants in CDIP or CFP packages.
Does the SN74ALS245ADBR support true bidirectional data flow without external logic?
Yes, the SN74ALS245ADBR supports true bidirectional data flow using its dedicated DIR (pin 1) and OE (pin 12) inputs. When OE is LOW, data transfers from A-to-B if DIR is HIGH, or from B-to-A if DIR is LOW. No external gates or latches are needed-this functionality is fully integrated and electrically specified in the datasheet's function table and timing diagrams.
What is the recommended decoupling strategy for the SN74ALS245ADBR?
TI recommends placing a 0.1 µF ceramic capacitor between VCC (pin 11) and GND (pin 10) as close as possible to the SN74ALS245ADBR-ideally within 5 mm-to suppress high-frequency supply noise. For systems with multiple transceivers, add a bulk 4.7 µF tantalum or aluminum electrolytic capacitor near the power entry point to stabilize low-frequency ripple.
Can the SN74ALS245ADBR replace a 74LS245 in an existing design?
Yes, the SN74ALS245ADBR is a functional and pin-compatible upgrade to the 74LS245, offering identical pinout, voltage thresholds, and logic behavior. Its ALS architecture provides faster propagation delay (10 ns vs. 15–20 ns) and lower power consumption, enabling direct drop-in replacement without layout changes-provided the SSOP-20 footprint matches the PCB land pattern.
Is the SN74ALS245ADBR RoHS compliant and lead-free?
Yes, the SN74ALS245ADBR is RoHS compliant and features NiPdAu (NIPDAU) lead finish. Per TI's packaging addendum, it carries MSL Level-1 rating with unlimited floor life and peak reflow temperature of 260°C, making it compatible with standard lead-free reflow profiles used in modern SMT assembly lines.
SN74ALS245ADBR 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:
- 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-SSOP
SN74ALS245ADBR FAQ
1.How can I place an order for SN74ALS245ADBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS245ADBR 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 SN74ALS245ADBR reliable?
The price and inventory of SN74ALS245ADBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS245ADBR is usually 5 days.
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4.How is shipping managed for SN74ALS245ADBR?
SN74ALS245ADBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS245ADBR 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 SN74ALS245ADBR?
For technical support, including SN74ALS245ADBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS245ADBR requirements.
6.How does Aetrix verify that SN74ALS245ADBR is sourced from the original manufacturer or authorized distributors?
All SN74ALS245ADBR 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 SN74ALS245ADBR meets industry standards.
7.What is the process for return or replacement of SN74ALS245ADBR?
All SN74ALS245ADBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS245ADBR, 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 SN74ALS245ADBR part is unused and in its original packaging.
Return procedure for SN74ALS245ADBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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