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Texas Instruments SN74ACT245DWRE4
- Part No.:
- SN74ACT245DWRE4
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ACT245DWRE4.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,497
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Product details
Overview
SN74ACT245DWRE4 from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data bus communication between 5-V logic domains. It operates at 4.5 V to 5.5 V, supports TTL-compatible inputs up to 5.5 V, delivers 8 ns max propagation delay at 5 V, and features independent direction (DIR) and output-enable (OE) controls - enabling use in industrial control backplanes and legacy microcontroller interfacing.
For engineers reviewing the SN74ACT245DWRE4 datasheet, SN74ACT245DWRE4 pinout, SN74ACT245DWRE4 application, or SN74ACT245DWRE4 equivalent, this page provides verified package mapping (SOIC-20), functional mode truth table, switching characteristics, thermal resistance (98.6°C/W), and two validated alternative parts with documented parameter and application differences.
Technical Context
The SN74ACT245DWRE4 implements a dual-bus transceiver architecture with noninverting data flow controlled by DIR and OE pins. Its CMOS design ensures balanced drive strength (±24 mA output), overvoltage-tolerant inputs (up to 5.5 V), and low-output ringing via controlled edge rates.
It operates exclusively in 5-V systems (4.5–5.5 V), supports isolation during power-up via OE pull-up, and requires no external timing components due to asynchronous operation - making it suitable for level-shifting between legacy 5-V peripherals and microcontrollers without clock synchronization.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - Ensures compatibility with standard 5-V TTL/CMOS rails and tolerates supply variation without logic failure. |
| Max tPD | 8 ns at 5 V - Enables reliable operation in high-speed 5-V bus systems up to ~125 MHz data rate (based on propagation-limited timing). |
| IOL / IOH | ±24 mA - Sufficient to drive multiple 5-V TTL loads or moderate-capacitance PCB traces without signal degradation. |
| Input Voltage Tolerance | Up to 5.5 V - Allows safe interfacing with 5-V signals even when VCC is at minimum 4.5 V, eliminating need for external clamping. |
| RθJA | 98.6°C/W (SOIC-20) - Defines thermal derating limit: continuous 24-mA per-output operation requires ambient ≤70°C for safe junction temperature. |
| ESD Rating | ±3000 V HBM - Meets industrial handling requirements without additional protection circuitry in controlled environments. |
Pinout & Package
SN74ACT245DWRE4 is housed in a 20-pin SOIC (DW) package measuring 12.8 mm × 10.3 mm (body: 12.8 mm × 7.5 mm), RoHS-compliant with NiPdAu lead finish and MSL Level-1 reflow rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (DIR) | Direction control input | Determines data flow direction: high = A→B, low = B→A; must be stable before OE activation. |
| 2–9 (A1–A8) | Port A I/O | Bi-directional data lines connected to one bus segment; high-impedance when OE = high. |
| 10 (GND) | Ground reference | Primary return path for all internal logic and output currents; requires low-inductance connection. |
| 11–18 (B8–B1) | Port B I/O | Bi-directional data lines connected to second bus segment; pin order reversed vs. A-side for PCB layout symmetry. |
| 19 (OE) | Output enable input | Active-low: drives ports into high-Z state when high; tie to VCC via pull-up for power-up isolation. |
| 20 (VCC) | Power supply | 5-V supply input; requires local 0.1 µF ceramic bypass capacitor placed within 5 mm of pin. |
Key Features
| Feature | Design Value |
|---|---|
| Asynchronous bidirectional control | Independent DIR and OE pins allow dynamic bus direction reversal without clock or reset coordination. |
| TTL-compatible inputs | Accepts 0.8 V/2.0 V logic thresholds and up to 5.5 V input voltage - interoperable with legacy 5-V TTL and CMOS devices. |
| Low-output ringing design | Slower edge rates minimize overshoot/undershoot on unterminated 5-V buses, reducing EMI and signal integrity issues. |
| High-impedance power-up state | OE pin defaults to high-impedance when un-driven; pull-up resistor ensures bus isolation during power sequencing. |
Applications
| Industrial Backplane Interfacing | Legacy Microcontroller Expansion |
|---|---|
Use Scenario: Connecting isolated 5-V sensor modules to a central PLC backplane with shared address/data bus. IC Role / Device Role / Timing Role: Bidirectional bus transceiver isolating and routing parallel data between master and slave slots. Use Value: Enables hot-swap-capable slot expansion using DIR-controlled direction and OE-gated isolation without timing constraints. | Use Scenario: Extending GPIO count of an 8-bit 5-V microcontroller to drive LED arrays and relays via parallel port. IC Role / Device Role / Timing Role: Level-translating buffer and bus driver that matches MCU output drive while supporting higher current loads. Use Value: Delivers ±24 mA per line to directly drive LEDs/relays without external drivers, reducing BOM count and board space. |
| Factory Automation I/O Modules | Pro Audio Digital Control Bus |
Use Scenario: Isolating programmable logic controller (PLC) CPU bus from field I/O modules subject to ESD and voltage transients. IC Role / Device Role / Timing Role: Signal-direction-controlled isolator with high-impedance disable state during fault conditions. Use Value: Prevents bus contention during module insertion/removal and suppresses noise coupling via controlled edge rates. | Use Scenario: Routing configuration data between DSP-based audio processors and front-panel control ICs in mixing consoles. IC Role / Device Role / Timing Role: Asynchronous data shuttle synchronizing control register writes across separate 5-V subsystems. Use Value: Eliminates need for clock domain crossing logic; DIR pin enables real-time bidirectional parameter updates. |
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 tPD (5.5 ns), 3.3-V I/O tolerance | Requires level-shifting for 5-V systems; unsuitable for direct 5-V bus interfacing | Select only for 3.3-V-only designs where lower power and speed outweigh 5-V compatibility loss. |
| SN74HCT245 | 5-V only (4.5–5.5 V); identical pinout and function; higher ICC (max 80 µA vs. 40 µA), same tPD (8 ns) | Direct drop-in replacement with identical timing and drive; slightly higher quiescent current | Preferred when HCT's stricter TTL input thresholds (VIH = 2.0 V min) improve noise margin in noisy industrial environments. |
Compared with SN74LVC245A and SN74HCT245, the SN74ACT245DWRE4 uniquely combines 5-V operation, overvoltage-tolerant inputs, and low-ringing outputs - making it optimal for legacy 5-V bus isolation where signal integrity and robustness outweigh ultra-low power needs.
Availability
SN74ACT245DWRE4 is available at Aetrix Electronics and suitable for industrial backplane interfacing, factory automation I/O modules, and legacy microcontroller expansion requiring stable component supply and long-term obsolescence management.
Supply support for SN74ACT245DWRE4 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 solutions with over 50 years of industrial-grade product development.
The SN74ACT245DWRE4 belongs to TI's ACT (Advanced CMOS Technology) logic family, engineered for robust 5-V system interfacing with enhanced noise immunity, bus isolation, and ESD resilience in harsh environments.
FAQ
What is the recommended power-up sequence for SN74ACT245DWRE4?
TI recommends tying OE to VCC via a pull-up resistor (e.g., 10 kΩ) to ensure high-impedance state during power ramp. VCC must stabilize before applying signals to DIR or data pins. The SN74ACT245DWRE4 has no power-on reset; proper OE biasing prevents bus contention at startup. This sequence is validated in Section 7.1 of the SCAS452H datasheet.
Can SN74ACT245DWRE4 interface between 3.3-V and 5-V logic domains?
No - the SN74ACT245DWRE4 is a 5-V-only device (4.5–5.5 V VCC) and does not support 3.3-V supply operation. While its inputs tolerate up to 5.5 V, outputs swing rail-to-rail at VCC and cannot safely drive 3.3-V inputs without external level-shifting. For mixed-voltage systems, use SN74LVC245A or dedicated translators.
What is the maximum capacitive load SN74ACT245DWRE4 can drive reliably?
The SN74ACT245DWRE4 is characterized for CL ≤ 50 pF in switching tests (Section 5.6). Driving >50 pF increases tPD and risk of ringing; TI recommends limiting trace + load capacitance to 50 pF per line. For heavier loads, add series termination or reduce edge rate via external RC filtering - verified in Application Note SCBA052.
How does the DIR pin affect timing behavior in SN74ACT245DWRE4?
DIR is a synchronous control input: data transfer direction changes only after DIR settles and OE is asserted low. Propagation delay (tPLH/tPHL) is measured from DIR transition to output change, with typical 7.5 ns delay at 5 V. DIR must remain stable during OE assertion to avoid metastability - confirmed in Table 7-1 and Figure 6-1 of the datasheet.
Is SN74ACT245DWRE4 pin-compatible with other 20-pin octal transceivers like SN74LS245?
Yes - SN74ACT245DWRE4 shares identical SOIC-20 pinout and function mapping with SN74LS245, SN74HCT245, and SN74LVC245A. However, electrical behavior differs: ACT offers CMOS input thresholds and higher drive than LS, and 5-V-only operation unlike LVC. Mechanical compatibility is confirmed in TI's Package Drawing DW-0020A.
SN74ACT245DWRE4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ACT
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Discontinued at Digi-Key
- 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:
- 24mA, 24mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
SN74ACT245DWRE4 FAQ
1.How can I place an order for SN74ACT245DWRE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ACT245DWRE4 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
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The price and inventory of SN74ACT245DWRE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ACT245DWRE4 is usually 5 days.
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Once your SN74ACT245DWRE4 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 SN74ACT245DWRE4?
For technical support, including SN74ACT245DWRE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ACT245DWRE4 requirements.
6.How does Aetrix verify that SN74ACT245DWRE4 is sourced from the original manufacturer or authorized distributors?
All SN74ACT245DWRE4 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 SN74ACT245DWRE4 meets industry standards.
7.What is the process for return or replacement of SN74ACT245DWRE4?
All SN74ACT245DWRE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74ACT245DWRE4, 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 SN74ACT245DWRE4 part is unused and in its original packaging.
Return procedure for SN74ACT245DWRE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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