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Texas Instruments SN74AHCT245N
- Part No.:
- SN74AHCT245N
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74AHCT245N.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:325
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Product details
Overview
SN74AHCT245N from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between 5 V buses. It operates from 4.5 V to 5.5 V, features TTL-compatible inputs (VIH = 2 V, VIL = 0.8 V), supports ±8 mA output drive, and delivers propagation delays as low as 4.5 ns (tPLH/tPHL, CL = 15 pF) in PDIP-20 package. It enables isolated bus communication in microcontroller peripheral expansion systems.
For engineers reviewing the SN74AHCT245N datasheet, SN74AHCT245N pinout, SN74AHCT245N application, or SN74AHCT245N equivalent, this page provides verified electrical specifications, functional mode mapping, real-world use cases, and validated alternative parts - all confirmed against TI's SCLS233S (Rev S, July 2023) production datasheet and orderable addendum.
Technical Context
The SN74AHCT245N implements dual-directional 8-bit data flow controlled by DIR (direction) and OE (output enable) logic inputs. Its CMOS design with TTL-voltage-compatible inputs allows seamless interfacing between legacy 5 V TTL logic and modern 5 V CMOS systems. The device uses balanced output drivers and slow edge rates to minimize ringing and overshoot on transmission lines.
Functional modes are strictly defined by OE/DIR combinations: OE = L + DIR = L routes B-bus data to A-bus; OE = L + DIR = H routes A-bus data to B-bus; OE = H forces all outputs into high-impedance state regardless of DIR. No internal latching or clocking is present - operation is fully asynchronous and level-sensitive.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures compatibility with standard 5 V logic rails and tolerance to supply ripple. |
| Input Voltage Thresholds | VIH = 2 V, VIL = 0.8 V - guarantees reliable recognition of TTL-level signals without level-shifting circuitry. |
| Output Drive Strength | ±8 mA (IOH/IOL) - sufficient for driving multiple 5 V CMOS loads while maintaining signal integrity. |
| Propagation Delay | tPLH/tPHL = 4.5 ns (typ), CL = 15 pF - enables high-speed bus handshaking in microcontroller I/O expansion. |
| 3-State Enable Time | tPZH/tPZL = 8.9 ns (typ), CL = 15 pF - ensures fast isolation during bus arbitration or controller reset sequences. |
| ESD Rating | HBM ±2000 V - meets industrial-grade robustness requirements for board-level handling and assembly. |
| Operating Temperature | –40°C to +125°C - qualified for extended industrial environments including motor control and power management systems. |
Pinout & Package
SN74AHCT245N is supplied in a 20-pin plastic dual in-line package (PDIP), with body dimensions of 25.40 mm × 6.35 mm and through-hole mounting compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (DIR) | Direction control input | Determines data flow direction: DIR = H enables A→B; DIR = L enables B→A. |
| 2–9 (A1–A8) | Port A bidirectional I/O | Connects to source bus (e.g., microcontroller data bus); functions as input or output based on DIR. |
| 10 (GND) | Ground reference | Primary return path for all internal logic and output currents; must be low-impedance. |
| 11–18 (B1–B8) | Port B bidirectional I/O | Connects to destination bus (e.g., peripheral memory or display interface); complements A-port function. |
| 19 (OE) | Output enable input | Active-low: OE = L enables transceiver; OE = H places all A/B pins in high-impedance state. |
| 20 (VCC) | Positive supply | 5 V nominal power rail; requires local 0.1 µF bypass capacitor per TI layout guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| TTL-voltage compatible inputs | Accepts 0.8 V / 2 V thresholds - eliminates need for external level shifters when interfacing with legacy TTL devices. |
| Asynchronous bidirectional operation | No clock or timing constraints required - simplifies integration into non-synchronous bus architectures like ISA or custom parallel interfaces. |
| Slow edge rate control | Minimizes output ringing and EMI on PCB traces - critical for noise-sensitive applications such as sensor front-ends or audio subsystems. |
| High-impedance isolation on OE | Ensures complete bus decoupling during reset or power sequencing - prevents back-driving and contention in multi-master systems. |
| Latch-up immunity | Exceeds 250 mA per JESD17 - enhances reliability in transient-prone industrial environments with shared ground planes. |
Applications
| Microcontroller Peripheral Expansion | Legacy System Bus Bridging |
|---|---|
|
Use Scenario: Expanding GPIO count of an MCU (e.g., MSP430 or STM32) to drive parallel LCD modules or SRAM chips. IC Role / Device Role / Timing Role: Bidirectional data buffer that isolates MCU data bus from peripheral address/data lines during idle cycles. Use Value: Enables direct 5 V bus connection without voltage translation, leveraging ±8 mA drive and 4.5 ns propagation delay for real-time response. |
Use Scenario: Interfacing a modern 5 V FPGA I/O bank with legacy 5 V TTL-based instrumentation hardware. IC Role / Device Role / Timing Role: Level-consistent transceiver ensuring VIH/VIL compatibility across mixed-technology subsystems. Use Value: Eliminates need for discrete resistor networks or dedicated level translators while maintaining signal fidelity up to 100 MHz effective throughput. |
| Industrial Controller Reset Hold | Switch Debouncing Interface |
|
Use Scenario: Holding sensor data stable during PLC CPU reset using OE-controlled high-Z isolation. IC Role / Device Role / Timing Role: Data latch substitute - maintains bus state via OE assertion while DIR remains static. Use Value: Provides deterministic hold behavior with tPZH ≤ 16 ns (max), preventing metastability in safety-critical monitoring loops. |
Use Scenario: Conditioning mechanical switch inputs (e.g., emergency stop buttons) before feeding to digital logic. IC Role / Device Role / Timing Role: Low-noise, high-impedance buffer that rejects contact bounce via controlled slew rate and 20 ns/V input transition limit. Use Value: Reduces firmware debounce overhead by delivering clean, ring-free edges to interrupt-capable GPIO pins. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT245N | Same pinout and function, but HCT family has higher ICC (max 80 µA vs AHCT's 40 µA) and slower tPLH (6 ns typ). | Suitable for lower-speed, cost-sensitive designs where static current is less critical than propagation delay. | Prefer SN74AHCT245N when minimizing propagation delay or dynamic power is essential. |
| 74LCX245M | Lower VCC range (2.0–3.6 V), 3.3 V–only operation; not 5 V tolerant; different pinout (SOIC-20 only). | Designed for 3.3 V systems only - cannot replace SN74AHCT245N in 5 V bus environments without level shifting. | Select only if migrating fully to 3.3 V logic; not a drop-in replacement for 5 V applications. |
Compared with SN74HCT245N and 74LCX245M, the SN74AHCT245N uniquely balances 5 V TTL compatibility, sub-5 ns propagation, and low ICC - making it optimal for mixed-voltage industrial controllers requiring deterministic timing and robust noise immunity.
Availability
SN74AHCT245N is available at Aetrix Electronics and suitable for microcontroller expansion, industrial bus bridging, PLC reset hold, and switch debouncing applications requiring stable component supply and long-term industrial lifecycle support.
Supply support for SN74AHCT245N 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 connectivity technologies, with over 90 years of innovation in industrial, automotive, and communications markets.
The SN74AHCT245N belongs to TI's 74AHCT logic family, engineered specifically for high-speed, low-power 5 V bus interfacing in industrial control, test equipment, and legacy system upgrades where TTL compatibility and noise resilience are mandatory.
FAQ
What is the maximum operating temperature range for SN74AHCT245N?
The SN74AHCT245N is rated for operation from –40°C to +125°C, meeting extended industrial temperature requirements. This specification is confirmed in Section 6.3 (Recommended Operating Conditions) of the TI SCLS233S datasheet, and applies specifically to the PDIP (N) package variant.
Does SN74AHCT245N support 3.3 V input signals?
Yes, SN74AHCT245N accepts 3.3 V logic levels as valid high inputs because its VIH threshold is specified at 2 V (min) across the full temperature range. Inputs may swing up to 5.5 V regardless of VCC, enabling safe 3.3 V-to-5 V translation without external circuitry.
Can SN74AHCT245N be used in place of SN74HCT245N?
SN74AHCT245N is pin-compatible and functionally equivalent to SN74HCT245N, but offers faster propagation delay (4.5 ns vs 6 ns typ) and lower quiescent current (40 µA vs 80 µA max). No PCB changes are required, though timing margins should be re-verified in high-speed layouts.
What is the recommended bypass capacitor for SN74AHCT245N?
Texas Instruments recommends a 0.1 µF ceramic capacitor placed as close as possible to the VCC pin (Pin 20) of the SN74AHCT245N. This value is specified in Section 9.3 (Power Supply Recommendations) to suppress high-frequency noise and stabilize the 5 V supply during output switching events.
How does the DIR pin affect data flow direction in SN74AHCT245N?
In SN74AHCT245N, the DIR pin controls unidirectional data routing: when DIR = HIGH, data flows from Port A (Pins 2–9) to Port B (Pins 11–18); when DIR = LOW, data flows from Port B to Port A. This mapping is explicitly defined in Table 8-1 (Function Table) of the official datasheet.
SN74AHCT245N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- 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:
- 8mA, 8mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74AHCT245N FAQ
1.How can I place an order for SN74AHCT245N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT245N 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 SN74AHCT245N reliable?
The price and inventory of SN74AHCT245N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT245N is usually 5 days.
3.What payment methods are accepted for SN74AHCT245N?
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4.How is shipping managed for SN74AHCT245N?
SN74AHCT245N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT245N 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 SN74AHCT245N?
For technical support, including SN74AHCT245N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT245N requirements.
6.How does Aetrix verify that SN74AHCT245N is sourced from the original manufacturer or authorized distributors?
All SN74AHCT245N 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 SN74AHCT245N meets industry standards.
7.What is the process for return or replacement of SN74AHCT245N?
All SN74AHCT245N units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT245N, 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 SN74AHCT245N part is unused and in its original packaging.
Return procedure for SN74AHCT245N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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