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Texas Instruments SN74ACT245RKSR
- Part No.:
- SN74ACT245RKSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-VFQFN Exposed Pad
- Datasheet:
-
SN74ACT245RKSR.pdf
- Description:
- OCTAL BUS TRANSCEIVERS WITH TTL-
- Quantity:
- Payment:
- Shipping:
Inventory:3,000
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Product details
Overview
SN74ACT245RKSR 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 from 4.5 V to 5.5 V, supports TTL-compatible inputs up to 5.5 V, delivers ≤8 ns propagation delay at 5 V, and features direction control (DIR) and output enable (OE) for flexible bus isolation-used in pro audio interconnects and factory automation I/O expansion.
For engineers reviewing the SN74ACT245RKSR datasheet, SN74ACT245RKSR pinout, SN74ACT245RKSR application, or SN74ACT245RKSR equivalent, this page provides verified functional modes, thermal resistance (RθJA = 67.7°C/W), VQFN-20 package dimensions (4.5 mm × 2.5 mm), and real-world interface constraints including ±24 mA drive capability and 15 pF I/O capacitance.
Technical Context
The SN74ACT245RKSR implements a dual-bus transceiver architecture with independent DIR and OE controls, enabling configurable data flow from A-to-B or B-to-A while maintaining high-impedance isolation when OE is high. Its AC logic family ensures compatibility with TTL voltage thresholds and robust noise immunity across industrial temperature ranges (–40°C to +85°C).
It uses CMOS technology with balanced output drive and intentionally slower edge rates to suppress output ringing-critical in high-speed digital interconnects where signal integrity on shared buses must be preserved without external termination. Input overvoltage tolerance (up to 5.5 V) allows safe interfacing with mixed-voltage systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - Ensures stable operation across standard 5-V supply tolerances and brown-out resilience. |
| Max Propagation Delay | 8 ns at 5 V - Enables reliable timing in 125-MHz bus cycles with margin for trace delays. |
| Output Drive | ±24 mA per pin - Sufficient to drive 50-Ω transmission lines or multiple TTL loads without buffering. |
| Input Voltage Tolerance | Up to 5.5 V - Permits direct connection to 5-V buses even when VCC is at minimum 4.5 V. |
| I/O Capacitance | 15 pF - Limits capacitive loading on high-speed traces, reducing slew-induced jitter. |
| RθJA | 67.7°C/W (VQFN-20) - Supports >300 mW power dissipation in still-air environments without forced cooling. |
| ESD Rating | ±3000 V HBM - Meets industrial handling requirements without additional protection circuitry. |
Pinout & Package
VQFN-20 (RKS) package: 4.5 mm × 2.5 mm body, 0.4 mm pitch, exposed thermal pad, RoHS-compliant NiPdAu lead finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 DIR | Direction control input | Low = B→A data flow; High = A→B data flow; determines bus polarity during active transfer. |
| 2–9 A1–A8 | Port A I/O terminals | Bidirectional data pins for first bus segment; tolerate 5.5 V regardless of VCC level. |
| 10 GND | Ground reference | Primary return path for all I/O and internal logic; connects to exposed thermal pad for heat dissipation. |
| 11–18 B8–B1 | Port B I/O terminals | Bidirectional data pins for second bus segment; electrically identical to A-side with same voltage tolerance. |
| 19 OE | Output enable input | Active-low control: OE = Low enables transceiver; OE = High forces all A/B pins into high-impedance state. |
| 20 VCC | Power supply | Single 4.5–5.5 V supply for core logic and I/O; requires local 0.1 µF bypass capacitor adjacent to pin. |
Key Features
| Feature | Design Value |
|---|---|
| Asynchronous bidirectional bus interface | Eliminates need for clock synchronization between source and destination buses-ideal for legacy parallel interfaces. |
| 3-state output control with OE and DIR | Enables dynamic bus arbitration: OE isolates both ports; DIR selects direction without requiring external logic sequencing. |
| Slow-edge-rate outputs | Reduces EMI and overshoot/undershoot on unterminated PCB traces-critical for clean signal integrity in compact layouts. |
| TTL-compatible input thresholds | VIH = 2.0 V, VIL = 0.8 V - Guarantees interoperability with legacy 5-V TTL, LVTTL, and CMOS logic families. |
| Overvoltage-tolerant inputs | Accepts up to 5.5 V regardless of VCC setting - simplifies level-shifting in mixed-supply systems without external clamps. |
Applications
| Pro Audio Digital Interconnect | Factory Automation I/O Expansion |
|---|---|
Use Scenario: Bidirectional data exchange between DSP-based audio processors and FPGA-configured I/O modules in stage lighting consoles. IC Role / Device Role / Timing Role: Bus transceiver managing time-critical control word transfers and status feedback across isolated 5-V domains. Use Value: 8 ns propagation delay ensures sub-microsecond round-trip latency; 3-state isolation prevents bus contention during firmware updates. | Use Scenario: Extending PLC backplane communication to remote sensor/actuator cards in modular control cabinets. IC Role / Device Role / Timing Role: Level-shifting transceiver bridging microcontroller GPIO banks to industrial 5-V fieldbus peripherals. Use Value: ±24 mA drive supports long cable runs; overvoltage-tolerant inputs withstand transient coupling in noisy factory environments. |
| Video Signage Controller Interface | Appliance Mainboard Subsystem Link |
Use Scenario: Synchronizing video timing signals and configuration data between ARM SoC and display driver ICs in digital signage players. IC Role / Device Role / Timing Role: Direction-controlled data bridge enabling command/response protocol over shared parallel bus. Use Value: DIR pin allows single transceiver to handle both register writes and status reads-reducing component count vs. unidirectional solutions. | Use Scenario: Isolating user-interface MCU from motor-control subsystem in smart washing machines during spin-cycle EMI events. IC Role / Device Role / Timing Role: OE-gated bus isolator that disconnects control lines during high-current load switching. Use Value: High-impedance state prevents false triggering of triacs or MOSFET drivers; RθJA = 67.7°C/W sustains reliability under sealed enclosure conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC245APWR | 3.3-V only (1.65–3.6 V), lower drive (±24 mA), smaller 5.1×4.9 mm VSSOP package | Suitable for 3.3-V-only systems; not 5-V tolerant; higher speed (tPD = 5.2 ns) but less noise margin | Select when migrating to low-voltage logic; avoid if interfacing with 5-V peripherals. |
| SN74ABT245N | 5-V only (4.5–5.5 V), higher drive (±64 mA), PDIP-20 package (24.3×9.4 mm), no overvoltage tolerance | Better for driving heavy capacitive loads; larger footprint; lacks 5.5-V input tolerance needed in mixed-signal boards | Choose for legacy through-hole designs or high-current bus stubs; not suitable for space-constrained VQFN layouts. |
Compared with SN74LVC245APWR and SN74ABT245N, the SN74ACT245RKSR uniquely combines 5-V operation, 5.5-V input tolerance, VQFN-20 miniaturization, and controlled edge rates-making it optimal for modern industrial and pro-audio PCBs requiring robustness, density, and signal integrity.
Availability
SN74ACT245RKSR is available at Aetrix Electronics and suitable for pro audio interconnects, factory automation I/O expansion, video signage controller interfaces, and appliance mainboard subsystem links requiring stable component supply across extended production lifecycles.
Supply support for SN74ACT245RKSR 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, with over 90 years of innovation in precision analog, power management, and logic devices.
The SN74ACT245RKSR belongs to TI's ACT (Advanced CMOS Technology) logic family, engineered for high-noise-immunity 5-V digital systems where timing predictability, bus isolation, and mixed-voltage interoperability are critical.
FAQ
What is the maximum operating temperature range for the SN74ACT245RKSR?
The SN74ACT245RKSR is rated for industrial operation from –40°C to +85°C. This range is validated per JEDEC JESD78 and confirmed in Section 5.3 of the official datasheet. The VQFN-20 package's RθJA of 67.7°C/W enables full-rated performance without derating under typical board-level airflow conditions. Thermal design should ensure the junction temperature remains below 125°C under worst-case power dissipation.
Does the SN74ACT245RKSR support 3.3-V logic inputs?
No, the SN74ACT245RKSR does not guarantee reliable operation with 3.3-V logic inputs. Its input thresholds (VIH = 2.0 V min, VIL = 0.8 V max) are optimized for 5-V TTL compatibility. While a 3.3-V high may exceed VIH in some cases, voltage margin is insufficient for robust noise immunity. For 3.3-V systems, TI recommends SN74LVC245A instead. The SN74ACT245RKSR requires ≥4.5 V VCC and expects 5-V signaling levels.
How should the OE pin be handled during power-up to prevent bus contention?
To ensure high-impedance state at power-up, OE must be held high (inactive) until VCC stabilizes. TI recommends tying OE to VCC via a pullup resistor-minimum value determined by the driving source's sink capability. A 10-kΩ resistor is typical. Floating OE is prohibited: it may float low during ramp-up, enabling unintended bus drive and risking contention or latch-up. The SN74ACT245RKSR datasheet explicitly states this in Section 7.1.
Can the SN74ACT245RKSR drive a 50-Ω transmission line directly?
Yes, the SN74ACT245RKSR can drive a 50-Ω line with acceptable signal integrity. Its ±24 mA output drive supports ~2 V swing into 50 Ω (per Ohm's Law), and its intentional slow edge rates (Δt/Δv = 8 ns/V) suppress ringing. However, for lengths >10 cm or multi-drop topologies, series termination near the driver output is recommended. The SN74ACT245RKSR's 15-pF Cio minimizes capacitive loading that would otherwise distort edges.
Is the exposed thermal pad on the SN74ACT245RKSR package required to be soldered?
Yes, the exposed thermal pad on the SN74ACT245RKSR (RKS package) must be soldered to a PCB thermal plane for electrical and thermal performance. It is internally connected to GND and serves as the primary heat conduction path. TI's packaging guidelines specify minimum solder paste coverage (>80%) and thermal via placement (≥4 vias, 0.3-mm diameter, filled or capped) beneath the pad. Omitting this compromises RθJA and risks exceeding junction temperature limits under sustained load.
SN74ACT245RKSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ACT
- Package/Case:
- 20-VFQFN Exposed Pad
- 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:
- 24mA, 24mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 20-VQFN (2.5x4.5)
SN74ACT245RKSR FAQ
1.How can I place an order for SN74ACT245RKSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ACT245RKSR 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 SN74ACT245RKSR reliable?
The price and inventory of SN74ACT245RKSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ACT245RKSR is usually 5 days.
3.What payment methods are accepted for SN74ACT245RKSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ACT245RKSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ACT245RKSR?
SN74ACT245RKSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ACT245RKSR 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 SN74ACT245RKSR?
For technical support, including SN74ACT245RKSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ACT245RKSR requirements.
6.How does Aetrix verify that SN74ACT245RKSR is sourced from the original manufacturer or authorized distributors?
All SN74ACT245RKSR 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 SN74ACT245RKSR meets industry standards.
7.What is the process for return or replacement of SN74ACT245RKSR?
All SN74ACT245RKSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74ACT245RKSR, 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 SN74ACT245RKSR part is unused and in its original packaging.
Return procedure for SN74ACT245RKSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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