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Texas Instruments SN74ALS245A-1N
- Part No.:
- SN74ALS245A-1N
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74ALS245A-1N.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,059
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Product details
Overview
SN74ALS245A-1N 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 48 mA low-level output current (IOL), achieves 5.5 ns max propagation delay at 5 V, and features pnp input structure to reduce DC loading. It is used in industrial control backplanes and legacy microprocessor data bus isolation.
For engineers reviewing the SN74ALS245A-1N datasheet, SN74ALS245A-1N pinout, SN74ALS245A-1N application, or SN74ALS245A-1N equivalent, key selection factors include its -1 version's enhanced 48 mA IOL rating, PDIP-20 package compatibility with through-hole manufacturing, 3-state control via DIR/OE logic, and operation within 0°C to 70°C commercial temperature range.
Technical Context
The SN74ALS245A-1N implements dual-directional bus transceivers using bipolar ALS (Advanced Low-Power Schottky) technology. Its DIR input selects data flow direction (A→B or B→A), while OE enables or isolates all outputs simultaneously. The device uses pnp-based inputs to minimize input current draw and supports direct connection to standard TTL bus lines without external pull-ups.
It exhibits asymmetric switching behavior: tPLH/tPHL propagation delays range from 3 ns to 10 ns depending on direction and voltage, while enable/disable times (tPZH/tPLZ/tPHZ/tPLZ) are specified down to 2 ns minimum under load. All timing parameters are guaranteed over 4.5–5.5 V supply and 50 pF capacitive load conditions.
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 ripple. |
| Max Propagation Delay | 5.5 ns at 5 V - Enables high-speed data transfer in 20–25 MHz bus systems with margin. |
| IOL (Low-Level Output) | 48 mA - Supports driving heavy capacitive loads or multiple TTL inputs without buffer amplification. |
| VIK (Input Clamp Voltage) | –1.5 V - Protects inputs against negative transients up to –1.5 V during hot-swap or ESD events. |
| θJA (Thermal Impedance) | 69 °C/W (PDIP-N) - Determines junction-to-ambient temperature rise under 60 mA ICCmax, critical for thermal derating. |
| Operating Temperature | 0°C to 70°C - Qualified for commercial-grade embedded systems and industrial control panels. |
| Output Type | 3-State (Tri-State) - Allows multiple devices to share a common bus without contention when disabled. |
Pinout & Package
SN74ALS245A-1N is housed in a 20-pin plastic dual in-line package (PDIP-N), 0.300-inch wide body, with standard through-hole mounting and 0.100-inch lead pitch. Pin 1 is located at the top-left corner adjacent to the notch or dot marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (DIR) | Direction Control Input | Logic level determines data flow: LOW = B→A, HIGH = A→B; active-high polarity relative to OE. |
| 2–9 (A1–A8) | Port A Data Inputs/Outputs | Bidirectional I/O pins connected to source bus; function as inputs or outputs based on DIR and OE state. |
| 10 (GND) | Ground Reference | Primary return path for all internal currents and logic thresholds; must be low-impedance connection. |
| 11 (VCC) | Power Supply | +5 V supply rail; bypass capacitor (0.1 µF) required near pin for noise suppression and transient response. |
| 12 (OE) | Output Enable Input | Active-LOW control: LOW enables transceiver, HIGH places all A/B outputs in high-impedance state. |
| 13–20 (B1–B8) | Port B Data Inputs/Outputs | Bidirectional I/O pins connected to destination bus; mirror A-side functionality with independent control. |
Key Features
| Feature | Design Value |
|---|---|
| pnp Input Structure | Reduces DC input current to ≤0.1 mA, minimizing loading on upstream drivers and improving fan-out capability. |
| Enhanced IOL Rating | 48 mA per output (–1 version only) enables direct drive of up to 12 standard TTL loads without external buffers. |
| 3-State Bus Isolation | Simultaneous high-impedance disable of all 16 I/Os via single OE pin prevents bus contention in multi-master systems. |
| ALS Process Technology | Combines Schottky clamping with low-power design to achieve 5.5 ns speed at 36–60 mA ICC, superior to standard LS. |
| Robust Absolute Ratings | Withstands 7 V VCC and VI, –1.5 V VIK, and –65°C to +150°C storage, supporting rework and harsh environments. |
Applications
| Industrial Backplane Interface | Legacy Microprocessor Bus Extension |
|---|---|
Use Scenario: Isolating CPU address/data buses from peripheral expansion slots in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional bus transceiver enabling synchronous read/write cycles between MPU and add-on I/O modules. Use Value: 48 mA IOL drives long PCB traces and multiple TTL peripherals; 5.5 ns tpd maintains timing integrity at 20 MHz bus clock. | Use Scenario: Extending Z80 or 8085 data bus across daughterboards in test equipment and instrumentation racks. IC Role / Device Role / Timing Role: Direction-controlled data bridge that switches A↔B paths under software control via DIR/OE signals. Use Value: pnp inputs reduce loading on aging MPU bus drivers; 3-state isolation prevents signal corruption during bus arbitration. |
| Automated Test Equipment (ATE) Signal Routing | Factory Automation I/O Hub |
Use Scenario: Multiplexing stimulus/response signals between DUT interface cards and main controller in boundary-scan testers. IC Role / Device Role / Timing Role: High-speed, low-latency transceiver synchronizing parallel test vectors with sub-10 ns timing windows. Use Value: Guaranteed 3 ns min tPHL/tPLH ensures deterministic setup/hold margins; PDIP package allows socketed field replacement. | Use Scenario: Consolidating discrete sensor/actuator signals into a centralized PLC backplane with shared data lanes. IC Role / Device Role / Timing Role: Octal-level bus repeater providing galvanic separation and signal integrity restoration between zones. Use Value: 69 °C/W θJA supports ambient temperatures up to 70°C in enclosed cabinets; RoHS-compliant NIPDAU finish ensures solderability. |
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 | Standard version with 24 mA IOL (vs. 48 mA in -1N); identical pinout, timing, and package. | Suitable where lower drive strength suffices; not interchangeable in high-fanout designs requiring 48 mA. | Select SN74ALS245A-1N when driving >6 TTL loads or long traces; use SN74ALS245AN for cost-sensitive, low-load applications. |
| SN74AS245N | AS-family variant: faster 7.5 ns max tpd but higher ICC (95 mA vs. 60 mA), 64 mA IOL, and different VIH/VIL thresholds. | Used in ultra-high-speed systems where propagation delay dominates power budget; requires stricter VIH validation. | Choose SN74AS245N only if system demands <8 ns tpd and can accommodate higher supply current and tighter input voltage margins. |
Compared with SN74ALS245AN and SN74AS245N, the SN74ALS245A-1N uniquely balances enhanced drive (48 mA), moderate speed (5.5 ns), and low power (60 mA ICC), making it optimal for industrial backplanes where reliability and fan-out outweigh raw speed.
Availability
SN74ALS245A-1N is available at Aetrix Electronics and suitable for industrial control backplanes, legacy microprocessor bus extension, and automated test equipment signal routing requiring stable component supply and long-term obsolescence management.
Supply support for SN74ALS245A-1N 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 SN74ALS245A-1N belongs to TI's ALS (Advanced Low-Power Schottky) logic product line, engineered for high-speed, low-power bidirectional bus interfacing in industrial and computing applications where TTL compatibility and robust drive capability are essential.
FAQ
What is the maximum output current capability of the SN74ALS245A-1N?
The SN74ALS245A-1N supports a maximum low-level output current (IOL) of 48 mA per pin when VCC is between 4.75 V and 5.25 V. This enhanced rating distinguishes the "-1" version from the standard SN74ALS245A (24 mA IOL) and enables direct drive of heavier TTL loads without external buffers. The high-level output current (IOH) remains –15 mA, consistent with ALS family specifications.
Does the SN74ALS245A-1N support bidirectional data flow, and how is direction controlled?
Yes, the SN74ALS245A-1N supports fully bidirectional data transfer between Port A and Port B. Direction is controlled by the DIR input: when DIR is LOW, data flows from Port B to Port A; when DIR is HIGH, data flows from Port A to Port B. This logic-level control operates independently of the OE (output enable) signal, allowing dynamic reversal of bus traffic under system software or hardware control.
What package type and mounting style does the SN74ALS245A-1N use?
The SN74ALS245A-1N uses a 20-pin plastic dual in-line package (PDIP-N) with 0.300-inch body width and through-hole leads. It is designed for wave or hand soldering onto printed circuit boards and is compatible with standard DIP sockets. The package carries the part marking "SN74ALS245A-1N" and meets RoHS requirements with NiPdAu (NIPDAU) lead finish.
How does the SN74ALS245A-1N achieve bus isolation when disabled?
When the OE (output enable) input is driven HIGH, all 16 I/O pins (A1–A8 and B1–B8) enter a high-impedance (3-state) condition, effectively disconnecting both ports from the bus. This isolation prevents signal contention in multi-device bus architectures and allows safe insertion/removal of modules. The transition time from active to high-Z is characterized by tPZH (2–20 ns) and tPLZ (2–15 ns), ensuring clean bus release.
Is the SN74ALS245A-1N compatible with standard TTL logic levels?
Yes, the SN74ALS245A-1N is fully TTL-compatible: its VIH threshold is 2.0 V (min), VIL is 0.8 V (max), VOH is ≥2.4 V (at IOL = 48 mA), and VOL is ≤0.5 V (at IOL = 48 mA). These values align with standard TTL input/output specifications, enabling seamless integration with 74LS, 74F, and legacy 74xx logic families without level-shifting circuitry.
SN74ALS245A-1N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ALS
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- 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:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74ALS245A-1N FAQ
1.How can I place an order for SN74ALS245A-1N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ALS245A-1N 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-1N reliable?
The price and inventory of SN74ALS245A-1N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ALS245A-1N is usually 5 days.
3.What payment methods are accepted for SN74ALS245A-1N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ALS245A-1N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ALS245A-1N?
SN74ALS245A-1N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ALS245A-1N 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-1N?
For technical support, including SN74ALS245A-1N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ALS245A-1N requirements.
6.How does Aetrix verify that SN74ALS245A-1N is sourced from the original manufacturer or authorized distributors?
All SN74ALS245A-1N 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-1N meets industry standards.
7.What is the process for return or replacement of SN74ALS245A-1N?
All SN74ALS245A-1N units undergo pre-shipment inspection (PSI). If there is an issue with SN74ALS245A-1N, 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-1N part is unused and in its original packaging.
Return procedure for SN74ALS245A-1N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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