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Texas Instruments SN74AHCT245DWR
- Part No.:
- SN74AHCT245DWR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74AHCT245DWR.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:5,651
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Product details
Overview
SN74AHCT245DWR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between two 8-bit buses in 5 V systems. It features TTL-compatible inputs (VIH = 2 V, VIL = 0.8 V), 4.5–5.5 V supply operation, ±8 mA output drive, and direction control via DIR pin with independent output enable (OE). It is used in microcontroller-to-peripheral bus isolation and level translation from 3.3 V logic to 5 V buses.
For engineers reviewing the SN74AHCT245DWR datasheet, SN74AHCT245DWR pinout, SN74AHCT245DWR application, or SN74AHCT245DWR equivalent, key selection criteria include 3-state timing (tPZH/tPLZ ≤ 16 ns at 50 pF), latch-up immunity (>250 mA), ESD robustness (±2000 V HBM), and SOIC-20 package compatibility with legacy 5 V board layouts.
Technical Context
The SN74AHCT245DWR implements dual 8-bit bidirectional I/O paths controlled by a single DIR input and a shared OE input. Its CMOS design with TTL-voltage-compatible inputs enables direct interfacing with legacy 5 V TTL and modern 3.3 V logic without external level shifters. The device operates only within the 4.5–5.5 V VCC range and does not support mixed-voltage operation on A/B ports.
Functional modes are strictly defined by OE and DIR: when OE = L, data flows A→B (DIR = H) or B→A (DIR = L); when OE = H, all A and B pins enter high-impedance state regardless of DIR. No internal pull-ups or pull-downs exist - unused inputs must be externally tied to VCC or GND per TI SCBA004 guidance.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - ensures stable operation across industrial 5 V rail tolerances. |
| IOH / IOL | –8 mA / +8 mA - sufficient drive for standard 5 V CMOS loads without signal degradation. |
| tPZH / tPLZ | ≤16 ns (CL = 50 pF) - defines maximum delay from OE assertion to bus isolation, critical for glitch-free bus arbitration. |
| VIH / VIL | 2.0 V / 0.8 V - guarantees reliable recognition of TTL and 3.3 V logic levels at A/B and control pins. |
| II (Input Leakage) | ±1 µA max - negligible current draw enables high-impedance bus hold without loading drivers. |
| ESD Rating | ±2000 V HBM - meets JEDEC JS-001 for robust handling in non-EPA assembly environments. |
| Latch-up Immunity | >250 mA per JESD17 - prevents destructive latch-up during transient overcurrent events. |
Pinout & Package
SN74AHCT245DWR uses a 20-pin SOIC (DW) package measuring 12.80 mm × 7.50 mm with standard 0.65 mm lead pitch and gull-wing leads. Thermal resistance RθJA is 96.2 °C/W, supporting operation up to +125°C ambient with appropriate PCB copper area.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DIR (Pin 1) | Direction control input | Logic level selects data flow direction: H = A→B, L = B→A; no effect when OE = H. |
| A1–A8 (Pins 2–9) | Port A bidirectional I/O | Connects to source bus; high-impedance when OE = H, regardless of DIR state. |
| GND (Pin 10) | Ground reference | Primary return path for all I/O and supply currents; must be low-inductance connection. |
| B8–B1 (Pins 11–18) | Port B bidirectional I/O | Connects to destination bus; electrically isolated from A port when OE = H. |
| OE (Pin 19) | Output enable input | Active-low control: L enables transceiver, H forces all A/B pins into 3-state mode. |
| VCC (Pin 20) | Positive supply | Must be decoupled with ≥0.1 µF ceramic capacitor placed adjacent to pin per TI layout guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| TTL-compatible inputs | Accepts 0.8 V/2.0 V thresholds - eliminates need for external level translators when interfacing with legacy TTL or 3.3 V microcontrollers. |
| Asymmetric edge rates | Slow rise/fall times minimize output ringing and overshoot on unterminated traces, reducing EMI in compact PCB layouts. |
| High-impedance isolation | OE-controlled 3-state outputs provide true electrical isolation between buses - essential for hot-swap and multi-master arbitration. |
| Overvoltage-tolerant inputs | Withstands VI up to 5.5 V independent of VCC - allows safe interfacing with higher-voltage signals during power sequencing. |
| Low static current | ICC ≤ 40 µA - reduces quiescent power in always-on subsystems such as system management controllers. |
Applications
| Microcontroller Bus Expansion | Industrial PLC Backplane 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 bus transceiver enabling time-multiplexed access to multiple peripherals while maintaining electrical isolation between active and idle devices. Use Value: Eliminates need for discrete logic gates or FPGA-based bus arbiters; supports deterministic 16 ns worst-case turnaround delay (tPLH + tPHL) at 50 pF load. | Use Scenario: Isolating CPU module from I/O modules on a DIN-rail mounted PLC backplane operating in noisy factory environments. IC Role / Device Role / Timing Role: Direction-controlled data bridge that prevents bus contention during module insertion/removal and controller reset sequences. Use Value: Latch-up immunity >250 mA and ±2000 V HBM ESD rating ensure reliability in high-noise industrial settings without additional protection circuitry. |
| Legacy System Voltage Translation | Test Equipment Digital Pattern Generator |
Use Scenario: Interfacing a 3.3 V FPGA I/O bank to a 5 V legacy sensor interface board requiring TTL-level signaling. IC Role / Device Role / Timing Role: Unidirectional or bidirectional level translator with direction control synchronized to FPGA state machine. Use Value: VIH = 2.0 V allows direct connection to 3.3 V outputs; slow edges suppress reflections on long ribbon cables between boards. | Use Scenario: Driving 5 V logic inputs of automated test equipment (ATE) from a 3.3 V pattern generator ASIC with precise timing control. IC Role / Device Role / Timing Role: Output buffer with programmable direction and fast 3-state enable/disable for test vector sequencing. Use Value: tPZH ≤ 16 ns ensures sub-20 ns setup time for synchronous test clock edges; ±8 mA drive supports fanout to 10+ 5 V CMOS inputs. |
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 (1.65–3.6 V), lower drive (±24 mA), faster switching (tPD ≈ 4.5 ns), no TTL input compatibility. | Suitable for pure 3.3 V systems; cannot replace SN74AHCT245DWR in 5 V or mixed-voltage designs. | Select only if full system operates at 3.3 V and higher speed is required; requires redesign of power and interface logic. |
| 74ACT245 | Same 5 V operation, identical pinout, but higher drive (±24 mA), faster propagation (tPD ≈ 6 ns), no guaranteed 3.3 V input compatibility. | Better for high-speed 5 V bus applications where noise margin is less critical than timing. | Drop-in replacement for SN74AHCT245DWR in existing SOIC-20 footprints if higher drive and speed are needed and TTL compatibility is not required. |
Compared with SN74LVC245A and 74ACT245, the SN74AHCT245DWR uniquely balances 5 V compatibility, TTL input tolerance, and moderate speed-making it optimal for upgrading legacy 5 V systems without altering power architecture or signal integrity margins.
Availability
SN74AHCT245DWR is available at Aetrix Electronics and suitable for industrial control systems, test equipment interfaces, and legacy microcontroller bus expansion requiring stable component supply and long-term production continuity.
Supply support for SN74AHCT245DWR 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 and embedded processing solutions for industrial, automotive, and personal electronics markets.
The SN74AHCT245 series belongs to TI's legacy logic portfolio, engineered specifically for robust 5 V bus interfacing with backward compatibility to TTL and forward compatibility to 3.3 V logic families.
FAQ
What is the maximum operating temperature for SN74AHCT245DWR?
The SN74AHCT245DWR is rated for operation from –40°C to +125°C ambient temperature. This extended industrial temperature range is validated per TI's recommended operating conditions and supported by thermal metrics including RθJA = 96.2 °C/W for the SOIC-20 package. Derating is not required up to 125°C when PCB copper area meets minimum thermal pad recommendations.
Does SN74AHCT245DWR support 3.3 V logic inputs directly?
Yes, SN74AHCT245DWR accepts 3.3 V logic inputs directly due to its TTL-compatible input thresholds: VIH = 2.0 V min and VIL = 0.8 V max. A 3.3 V CMOS output (VOH ≥ 3.0 V) exceeds the 2.0 V VIH requirement, ensuring reliable high-level recognition without external biasing or level shifting.
Can SN74AHCT245DWR be used for unidirectional data transfer?
Yes, SN74AHCT245DWR supports unidirectional operation by holding DIR at a fixed logic level (H for A→B, L for B→A) while using OE to enable/disable the path. This configuration is commonly used in memory-mapped I/O or peripheral address/data separation, where direction remains static during normal operation.
What is the recommended bypass capacitor for SN74AHCT245DWR?
Texas Instruments recommends a 0.1 µF ceramic capacitor placed as close as possible to the VCC pin (Pin 20) of SN74AHCT245DWR. For systems with multiple logic devices sharing the same 5 V rail, paralleling a 1 µF capacitor nearby improves low-frequency noise suppression while the 0.1 µF handles high-frequency transients.
Is SN74AHCT245DWR pin-compatible with other 74-series transceivers?
SN74AHCT245DWR is pin-compatible with industry-standard 74245-family transceivers in SOIC-20 (DW) package, including 74HC245, 74HCT245, and 74ACT245. Pin functions (DIR, OE, A1–A8, B1–B8, GND, VCC) match exactly, enabling drop-in replacement where voltage and timing requirements align.
SN74AHCT245DWR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- Package/Case:
- 20-SOIC (0.295", 7.50mm 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-SOIC
SN74AHCT245DWR FAQ
1.How can I place an order for SN74AHCT245DWR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT245DWR 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 SN74AHCT245DWR reliable?
The price and inventory of SN74AHCT245DWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT245DWR is usually 5 days.
3.What payment methods are accepted for SN74AHCT245DWR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT245DWR transactions.
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4.How is shipping managed for SN74AHCT245DWR?
SN74AHCT245DWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT245DWR 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 SN74AHCT245DWR?
For technical support, including SN74AHCT245DWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT245DWR requirements.
6.How does Aetrix verify that SN74AHCT245DWR is sourced from the original manufacturer or authorized distributors?
All SN74AHCT245DWR 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 SN74AHCT245DWR meets industry standards.
7.What is the process for return or replacement of SN74AHCT245DWR?
All SN74AHCT245DWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT245DWR, 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 SN74AHCT245DWR part is unused and in its original packaging.
Return procedure for SN74AHCT245DWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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