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Texas Instruments SN74AHCT245NSR
- Part No.:
- SN74AHCT245NSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHCT245NSR.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,947
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Product details
Overview
SN74AHCT245NSR 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, accepts TTL-compatible inputs (VIH = 2 V, VIL = 0.8 V), delivers ±8 mA output drive, and supports isolation via active-low OE and direction control via DIR pin - used in microcontroller-to-peripheral bus interfacing, level translation, and signal gating.
For engineers reviewing the SN74AHCT245NSR datasheet, SN74AHCT245NSR pinout, SN74AHCT245NSR application, or SN74AHCT245NSR equivalent, key selection criteria include its 20-pin SOP package, 3-state bidirectional operation, 5 V supply compatibility, TTL-level input acceptance, and 10 ns typical propagation delay under 15 pF load.
Technical Context
The SN74AHCT245NSR implements dual-bus bidirectional communication using a single DIR control line to select data flow direction (A→B or B→A) and an active-low OE input to place all outputs in high-impedance state. Its CMOS design with TTL-compatible inputs enables reliable interfacing between legacy 5 V logic and mixed-voltage systems.
It features slow edge rates to minimize output ringing and overshoot, supports up-translation from 3.3 V to 5 V logic domains, and maintains latch-up immunity exceeding 250 mA per JESD 17. The device is rated for operation from –40°C to 125°C and exhibits 13 pF typical power dissipation capacitance at 1 MHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures stable operation across industrial 5 V rail tolerances |
| Input Voltage Thresholds | VIH = 2 V, VIL = 0.8 V - guarantees interoperability with standard TTL outputs |
| Output Drive | ±8 mA at VOH/VOL - sufficient for driving multiple CMOS loads without external buffering |
| Propagation Delay | tPLH/tPHL = 10 ns max (CL = 15 pF) - enables reliable timing in 50 MHz–100 MHz bus applications |
| 3-State Enable Time | tPZH/tPHZ = 16.5 ns max (CL = 15 pF) - defines minimum bus turnaround latency during direction switching |
| Operating Temperature | –40°C to +125°C - qualified for extended industrial and automotive under-hood environments |
| ESD Rating | HBM ±2000 V, CDM ±1000 V - meets standard handling requirements for automated assembly |
Pinout & Package
The SN74AHCT245NSR is supplied in a 20-pin SOP (Small Outline Package) with 12.60 mm × 5.30 mm body size and gull-wing leads. It uses standard JEDEC MS-013AC footprint and is compatible with reflow soldering per Level-1 MSL rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DIR (Pin 1) | Direction control input | High = A→B data flow; Low = B→A data flow - determines real-time bus directionality |
| A1–A8 (Pins 2–9) | Port A I/O terminals | Bidirectional data lines connected to source bus; high-impedance when OE = high |
| GND (Pin 10) | Ground reference | Primary return path for all internal logic and I/O current - must be low-inductance connection |
| B8–B1 (Pins 11–18) | Port B I/O terminals | Bidirectional data lines connected to destination bus; functionally identical to A-side pins |
| OE (Pin 19) | Output enable input | Active-low - disables both A and B ports simultaneously into high-Z state for bus isolation |
| VCC (Pin 20) | Positive supply | 5 V nominal power rail; requires local 0.1 µF bypass capacitor placed adjacent to pin |
Key Features
| Feature | Design Value |
|---|---|
| TTL-compatible inputs | Accepts 0.8 V/2 V thresholds - eliminates need for external level-shifting when interfacing with legacy 5 V TTL devices |
| Slow edge rate control | Minimizes output ringing and EMI on PCB traces - critical for noise-sensitive industrial control backplanes |
| 3-state bus isolation | Simultaneous high-Z disable of all 16 I/Os via single OE pin - prevents bus contention during reset or standby |
| 5 V optimized CMOS | Low ICC = 40 µA max - reduces static power in always-on system monitoring functions |
| Wide temperature range | –40°C to +125°C operation - supports deployment in engine control units and motor drive inverters |
Applications
| Microcontroller Bus Expansion | Legacy System Interface |
|---|---|
Use Scenario: Expanding GPIO count of an ARM Cortex-M4 MCU by connecting parallel peripherals (ADC, DAC, GPIO expander) via shared 8-bit data bus. IC Role / Device Role / Timing Role: Bidirectional data bridge enabling time-multiplexed access to multiple peripherals without address decoding overhead. Use Value: Eliminates need for discrete logic or FPGA glue logic; leverages existing 5 V bus architecture while maintaining <10 ns timing margin. |
Use Scenario: Interfacing modern microcontroller development board with vintage 5 V TTL-based test equipment (logic analyzers, pattern generators). IC Role / Device Role / Timing Role: Level- and protocol-transparent bus translator ensuring signal integrity across mixed-generation digital subsystems. Use Value: Preserves original timing behavior with no added setup/hold penalties; supports hot-plug-safe isolation via OE control. |
| Industrial I/O Module | Power Supply Sequencing Control |
Use Scenario: Isolating fieldbus controller from sensor/actuator interface cards in programmable logic controller (PLC) backplane. IC Role / Device Role / Timing Role: Direction-controlled data conduit enabling read/write cycles between master and slave modules during runtime. Use Value: Enables deterministic bus arbitration with sub-100 ns turnaround; withstands industrial ESD events per IEC 61000-4-2. |
Use Scenario: Gating clock or reset signals between power domains during controlled startup/shutdown sequences in multi-rail embedded systems. IC Role / Device Role / Timing Role: Signal-enabling switch that blocks downstream logic until primary 5 V rail stabilizes. Use Value: Prevents metastability in downstream logic; OE tied to supervisor IC output ensures glitch-free enablement. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC245A | 3.3 V only supply (1.65–3.6 V); higher speed (tPD = 5.5 ns); lower drive (±24 mA) | Requires level shifters for 5 V systems; unsuitable for direct TTL interface | Select when operating exclusively in 3.3 V domains with tighter timing budgets |
| 74AHCT245 (Nexperia) | Functionally identical pinout and specs; same 4.5–5.5 V range and TTL compatibility | Drop-in replacement with identical thermal and ESD performance; RoHS-compliant lead finish | Preferred for second-source assurance in long-lifecycle industrial designs |
Compared with SN74AHCT245NSR, the SN74LVC245A offers faster switching but lacks native 5 V tolerance, while the Nexperia 74AHCT245 provides full functional equivalence with alternate supply chain validation - making it ideal for dual-sourcing strategies requiring zero layout change.
Availability
SN74AHCT245NSR is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and embedded test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SN74AHCT245NSR 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 connectivity solutions for industrial, automotive, and personal electronics markets.
The SN74AHCT245NSR belongs to TI's legacy 74AHCT logic family, engineered for robust 5 V bus interfacing with TTL compatibility, high noise immunity, and extended temperature reliability - targeting industrial control, instrumentation, and legacy system upgrades.
FAQ
What is the maximum operating temperature for the SN74AHCT245NSR?
The SN74AHCT245NSR is rated for continuous operation from –40°C to +125°C ambient temperature. This specification is validated per the Recommended Operating Conditions table in the official datasheet (SCLS233S, Rev S), and applies specifically to the NS package variant. Thermal derating is not required within this range when mounted per JEDEC standards with adequate PCB copper pour.
Does the SN74AHCT245NSR support 3.3 V logic inputs?
Yes, the SN74AHCT245NSR accepts 3.3 V logic inputs reliably because its VIH threshold is specified at 2 V min and VIL at 0.8 V max over temperature. When driven by a 3.3 V CMOS source, the input voltage exceeds VIH by >1.3 V margin, ensuring robust high-level recognition without external biasing - confirmed in Section 6.3 and 8.3 of the datasheet.
Can the SN74AHCT245NSR be used for level translation between 3.3 V and 5 V buses?
Yes, the SN74AHCT245NSR supports unidirectional and bidirectional level translation from 3.3 V to 5 V. Its TTL-compatible inputs accept 3.3 V as valid high, and its 5 V-tolerant outputs drive 5 V logic levels. However, it does not translate 5 V inputs down to 3.3 V - the B-side outputs remain at 5 V, so downstream 3.3 V receivers require external clamping or voltage dividers.
What is the recommended bypass capacitor for the SN74AHCT245NSR VCC pin?
Texas Instruments recommends a 0.1 µF ceramic capacitor placed as close as possible to the VCC pin (Pin 20) of the SN74AHCT245NSR. This value is specified in Section 9.3 of the datasheet for single-supply devices and is effective for suppressing high-frequency supply noise generated during output switching transitions.
Is the SN74AHCT245NSR pin-compatible with other 74-series transceivers like the 74LS245?
No, the SN74AHCT245NSR is not pin-compatible with the 74LS245. While both are 20-pin octal transceivers, the LS245 uses different pin assignments (e.g., OE on Pin 1, DIR on Pin 19) and lacks TTL-compatible input thresholds. The SN74AHCT245NSR follows the industry-standard AHCT pinout defined in TI's SCLS233S, which differs electrically and physically from bipolar LS logic.
SN74AHCT245NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- Package/Case:
- 20-SOIC (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:
- 8mA, 8mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74AHCT245NSR FAQ
1.How can I place an order for SN74AHCT245NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT245NSR 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 SN74AHCT245NSR reliable?
The price and inventory of SN74AHCT245NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT245NSR is usually 5 days.
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SN74AHCT245NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT245NSR 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 SN74AHCT245NSR?
For technical support, including SN74AHCT245NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT245NSR requirements.
6.How does Aetrix verify that SN74AHCT245NSR is sourced from the original manufacturer or authorized distributors?
All SN74AHCT245NSR 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 SN74AHCT245NSR meets industry standards.
7.What is the process for return or replacement of SN74AHCT245NSR?
All SN74AHCT245NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT245NSR, 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 SN74AHCT245NSR part is unused and in its original packaging.
Return procedure for SN74AHCT245NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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