My Inquiry
My Account
Texas Instruments SN74ALS245ADB
- Part No.:
- SN74ALS245ADB
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74ALS245ADB.pdf
- Description:
- PROTOTYPE
- Quantity:
- Payment:
- Shipping:
Inventory:3,574
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SN74ALS245ADB 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 isolation.
For engineers reviewing the SN74ALS245ADB datasheet, SN74ALS245ADB pinout, SN74ALS245ADB application, or SN74ALS245ADB equivalent, key selection factors include its 20-pin SSOP (DB) package, direction-control (DIR) and output-enable (OE) logic interface, 3-state bus driving capability, and compatibility with ALS logic family timing and voltage thresholds.
Technical Context
This device implements dual-directional 8-bit data routing controlled by DIR and OE inputs: when OE is low, data flows A→B if DIR = high or B→A if DIR = low; when OE is high, all outputs enter high-impedance state. Its pnp input stage lowers input current draw compared to standard TTL, reducing bus loading.
Switching performance is characterized under CL = 50 pF, R1 = R2 = 500 Ω, and VCC = 4.5–5.5 V, with tPLH/tPHL ≤ 10 ns and enable/disable times (tPZH/tPLZ) ≤ 20 ns. Absolute maximum ratings include 7 V supply and 5.5 V I/O voltage, with thermal impedance θJA = 70°C/W for the DB package.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - ensures compatibility with standard 5 V TTL power rails and tolerates supply variation without functional degradation. |
| Max Propagation Delay | 10 ns at VCC = 5 V - enables reliable operation in high-speed 8-bit bus systems up to ~100 MHz effective data rate. |
| IOL / IOH | ±24 mA - provides sufficient drive strength to directly terminate and drive multiple TTL loads on shared bus lines. |
| Input Structure | pnp-based - reduces DC input current to ≤ ±0.1 mA, minimizing steady-state bus loading and power consumption. |
| 3-State Enable Time | tPZH ≤ 20 ns - guarantees fast bus release during mode switching, critical for time-multiplexed bus arbitration. |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded and industrial control applications. |
| Package | SSOP-20 (DB) - 7.5 mm × 5.6 mm footprint with 0.65 mm pitch, optimized for space-constrained PCB layouts. |
Pinout & Package
SN74ALS245ADB is housed in a 20-pin Small Outline Shrink Plastic (SSOP) package (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.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | DIR | Direction control input: high enables A→B data flow; low enables B→A data flow. |
| 2–9 | A1–A8 | Input/output port A - bidirectional data terminals connected to one bus segment. |
| 10 | GND | Ground reference for all internal circuitry and I/O. |
| 11 | VCC | Positive supply rail (4.5–5.5 V) powering logic core and output drivers. |
| 12 | OE | Output enable input: low activates transceiver; high places all A/B outputs in high-impedance state. |
| 13–20 | B1–B8 | Input/output port B - bidirectional data terminals connected to second bus segment. |
Key Features
| Feature | Design Value |
|---|---|
| Asynchronous bidirectional data routing | Enables flexible A↔B bus communication without clock synchronization, simplifying glue logic in legacy CPU and peripheral interconnects. |
| pnp input structure | Reduces input current to ≤ ±0.1 mA, lowering cumulative DC loading on shared address/data buses and improving noise margin stability. |
| 3-state outputs with fast enable/disable | tPZH/tPLZ ≤ 20 ns ensures rapid bus isolation during arbitration, preventing contention in multi-master systems. |
| TTL-compatible voltage thresholds | VIH = 2.0 V, VIL = 0.8 V - matches standard TTL logic families, enabling direct interface with 74LS/74ALS/74AS devices without level shifting. |
| Robust absolute ratings | 7 V VCC and 5.5 V I/O tolerance allow safe operation during power sequencing, hot-swap events, and transient overvoltage conditions. |
Applications
| Industrial Backplane Interface | Legacy Microprocessor Bus Isolation |
|---|---|
Use Scenario: Isolating CPU address/data buses from peripheral expansion slots in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing data flow between Z80 or 8086 CPU bus and modular I/O cards. Use Value: Prevents bus contention during card insertion/removal and supports hot-swap-safe 3-state control via OE signal. | Use Scenario: Interfacing memory-mapped peripherals to 8-bit microcontrollers in test equipment and instrumentation. IC Role / Device Role / Timing Role: Level-shifting and direction-controlled data bridge between MCU data bus and external EEPROM or UART. Use Value: Eliminates need for discrete logic gates; DIR pin allows single-wire control of read/write direction. |
| Automated Test Equipment (ATE) Signal Routing | Digital Panel Meter Data Multiplexing |
Use Scenario: Routing measurement data from multiple DMM channels to a central controller in rack-mounted ATE systems. IC Role / Device Role / Timing Role: High-speed octal bus switch enabling time-division multiplexing of sensor readings onto shared data lines. Use Value: 10 ns propagation delay ensures sub-microsecond channel switching latency, preserving measurement timing integrity. | Use Scenario: Sharing a single 8-bit display driver among multiple analog input channels in front-panel meters. IC Role / Device Role / Timing Role: Bidirectional data path between ADC output registers and common LED/LCD driver bus. Use Value: 3-state outputs allow dynamic bus ownership handoff between channels without hardware switches or relays. |
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 | Same ALS logic family, identical electrical specs, but in SOIC-20 (DW) package with 10.8 mm × 7.5 mm footprint and 1.27 mm pitch. | Requires PCB layout change due to larger body size and wider lead spacing; better thermal dissipation (θJA = 58°C/W vs. 70°C/W). | Select when board space permits larger package and higher thermal margin is needed for sustained 24 mA output loading. |
| SN74AS245ADBR | AS-family variant: faster tPLH/tPHL (7.5 ns max), higher IOL (48 mA), but increased ICC (up to 143 mA) and reduced noise margin (VIL = 0.8 V only). | Suitable for speed-critical paths where propagation delay dominates over power budget; not drop-in due to different DC characteristics. | Select when system timing budget demands <8 ns delay and load drive exceeds 24 mA, accepting higher supply current and tighter VIH/VIL windows. |
Compared with SN74ALS245ADWR and SN74AS245ADBR, the SN74ALS245ADB offers optimal balance of speed (10 ns), power efficiency (ICC ≤ 55 mA), and compact SSOP packaging - making it preferred for space-constrained industrial control boards requiring proven ALS reliability.
Availability
SN74ALS245ADB is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy microprocessor bus isolation, and automated test equipment signal routing requiring stable component supply across extended product lifecycles.
Supply support for SN74ALS245ADB 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 ICs, with decades of heritage in TTL and advanced logic families.
The SN74ALS245ADB belongs to TI's legacy ALS (Advanced Low-Power Schottky) logic portfolio, engineered for high-speed, low-power bidirectional bus interfacing in industrial and military-grade systems where reliability and long-term availability are critical.
FAQ
What is the maximum operating temperature range for the SN74ALS245ADB?
The SN74ALS245ADB is rated for commercial operation from 0°C to 70°C. This range is specified in the recommended operating conditions table of the official Texas Instruments datasheet SDAS272A, and applies specifically to the DB-package variants including SN74ALS245ADB and SN74ALS245ADBR. Devices in CDIP or CFP packages (e.g., SNJ54ALS245AJ) support –55°C to 125°C, but SN74ALS245ADB does not.
Does the SN74ALS245ADB support true bidirectional data flow without external logic?
Yes, the SN74ALS245ADB supports true bidirectional data flow using only its DIR and OE pins. When OE is low, setting DIR = high routes data from A1–A8 to B1–B8; DIR = low routes from B1–B8 to A1–A8. No additional gates or control circuitry are required - this functionality is built into the internal logic architecture of the SN74ALS245ADB.
What is the output drive capability of the SN74ALS245ADB at 5 V supply?
At VCC = 5 V, the SN74ALS245ADB delivers ±24 mA output current per pin (IOL = 24 mA, IOH = –24 mA), as specified in the "electrical characteristics" table of the SDAS272A datasheet. This drive strength allows direct connection to up to 10 standard TTL loads and ensures robust signal integrity on terminated 50 Ω bus traces.
Can the SN74ALS245ADB be used with 3.3 V logic systems?
No, the SN74ALS245ADB is not compatible with 3.3 V logic systems. Its absolute minimum VCC is 4.5 V, and input thresholds (VIH = 2.0 V, VIL = 0.8 V) are defined for 5 V operation. Driving its inputs from 3.3 V sources risks marginal or non-functional behavior; level translation is required for interoperability with 3.3 V domains.
What is the pin 1 marking and orientation for the SN74ALS245ADB SSOP package?
The SN74ALS245ADB uses a standard SSOP-20 (DB) package with pin 1 located at the top-left corner, identified by a small circular index area adjacent to the lead. The top-side marking is "G245A", as confirmed in TI's Package Option Addendum. The device follows JEDEC MO-150 registration, and the land pattern requires 0.65 mm pitch with 0.45 mm pad width.
SN74ALS245ADB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Bulk
- 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, 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
SN74ALS245ADB FAQ
1.How can I place an order for SN74ALS245ADB through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS245ADB 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 SN74ALS245ADB reliable?
The price and inventory of SN74ALS245ADB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS245ADB is usually 5 days.
3.What payment methods are accepted for SN74ALS245ADB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS245ADB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS245ADB?
SN74ALS245ADB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS245ADB 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 SN74ALS245ADB?
For technical support, including SN74ALS245ADB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS245ADB requirements.
6.How does Aetrix verify that SN74ALS245ADB is sourced from the original manufacturer or authorized distributors?
All SN74ALS245ADB 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 SN74ALS245ADB meets industry standards.
7.What is the process for return or replacement of SN74ALS245ADB?
All SN74ALS245ADB units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS245ADB, 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 SN74ALS245ADB part is unused and in its original packaging.
Return procedure for SN74ALS245ADB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74ALS245ADB Tags
-
SN74LVC1G17DBVR
Texas Instruments
-
SN74LVC1G07DCKR
Texas Instruments
-
SN74LVC1G17DCKR
Texas Instruments
-
SN74LVC1G07DBVR
Texas Instruments
-
SN74LVC1G125DCKR
Texas Instruments
-
SN74AHCT1G126DBVR
Texas Instruments
-
SN74LVC1G125DBVR
Texas Instruments
-
SN74AHCT1G125DBVR
Texas Instruments
-
SN74LVC2G17DBVR
Texas Instruments
-
SN74LVC2G07DCKR
Texas Instruments
-
SN74LVC1G34DCKR
Texas Instruments
-
SN74LVC2G17DCKR
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
