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Texas Instruments SN74AC245RKSR
- Part No.:
- SN74AC245RKSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-VFQFN Exposed Pad
- Datasheet:
-
SN74AC245RKSR.pdf
- Description:
- OCTAL BUS TRANSCEIVER WITH 3-STA
- Quantity:
- Payment:
- Shipping:
Inventory:3,000
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Product details
Overview
SN74AC245RKSR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in mixed-voltage systems. It operates from 2 V to 6 V, accepts input voltages up to 6 V, delivers ≤7 ns propagation delay at 5 V, and features direction control (DIR) and output enable (OE) for flexible bus isolation-used in factory automation I/O expansion and pro audio digital signal routing.
For engineers reviewing the SN74AC245RKSR datasheet, SN74AC245RKSR pinout, SN74AC245RKSR application, or SN74AC245RKSR equivalent, this page provides verified package mapping (20-pin VQFN-RKS), functional mode truth table, thermal resistance (RθJA = 67.7°C/W), ESD ratings (±3000 V HBM), and real-world switching characteristics across 3.3 V and 5 V supply conditions.
Technical Context
The SN74AC245RKSR implements dual-bus bidirectional communication using a single DIR input to select A→B or B→A data flow, while OE independently places all outputs in high-impedance state. Its CMOS design ensures balanced drive strength and slow edge rates to suppress output ringing in noise-sensitive applications.
It supports mixed-voltage interfacing: inputs tolerate up to 6 V regardless of VCC, enabling connection to higher-voltage logic without level shifters. The device operates across –40°C to +85°C and is qualified for industrial environments per its recommended operating conditions and thermal metrics.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC range | 2 V to 6 V - enables interoperability across 3.3 V and 5 V subsystems without external regulators |
| Max tpd @ 5 V | 7 ns - guarantees sub-10 ns timing margin for 100 MHz bus handshaking in synchronous interfaces |
| Input voltage tolerance | Up to 6 V - allows direct connection to legacy 5 V logic even when powered from 3.3 V |
| Output drive (IOL/IOH) | ±24 mA @ 4.5–5.5 V - sufficient to drive 50 Ω transmission lines or multiple CMOS loads |
| RθJA (VQFN) | 67.7°C/W - supports continuous operation at full load in compact PCB layouts with minimal heatsinking |
| HBM ESD rating | ±3000 V - meets industrial handling requirements without additional protection circuitry |
| Operating temperature | –40°C to +85°C - certified for use in factory automation controllers and outdoor signage electronics |
Pinout & Package
SN74AC245RKSR uses a 20-pin VQFN package (RKS) with 4.5 mm × 2.5 mm body size, wettable flank leads, and exposed thermal pad for enhanced heat dissipation. Pin 1 is located in Quadrant Q1 per tape-and-reel orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 DIR | Direction control input | Low = B→A data flow; High = A→B data flow - determines real-time bus polarity |
| 2–9 A1–A8 | Port A I/O terminals | Bidirectional data pins for first bus interface; internally isolated when OE = High |
| 10 GND | Ground reference | Primary return path for all signals and power; must be low-inductance connection to minimize noise |
| 11–18 B8–B1 | Port B I/O terminals | Bidirectional data pins for second bus; pin order reversed vs. A-side to simplify PCB routing symmetry |
| 19 OE | Output enable input | Low = active transceiver; High = all A/B pins enter high-Z - enables bus sharing and hot-swap isolation |
| 20 VCC | Power supply | Single-supply rail supporting 2–6 V; requires local 0.1 µF bypass capacitor adjacent to pin |
Key Features
| Feature | Design Value |
|---|---|
| Wide VCC range (2–6 V) | Eliminates need for dedicated level translators when interfacing 3.3 V microcontrollers to 5 V peripherals |
| Input overvoltage tolerance (to 6 V) | Prevents latch-up or damage when A/B buses operate at higher voltages than VCC, e.g., 5 V sensors on 3.3 V MCU bus |
| Slow edge rate design | Reduces EMI and overshoot/undershoot on PCB traces - critical for video timing and audio clock distribution |
| High-impedance isolation via OE | Enables dynamic bus arbitration in multi-master systems without external switches or multiplexers |
| VQFN thermal performance (RθJA = 67.7°C/W) | Supports sustained 24 mA per output in space-constrained industrial modules without derating |
Applications
| Factory Automation I/O Expansion | Pro Audio Digital Signal Routing |
|---|---|
|
Use Scenario: Connecting PLC CPU modules to distributed I/O racks with mixed 3.3 V and 5 V sensor/actuator interfaces. IC Role / Device Role / Timing Role: Bidirectional data bridge between controller and remote terminal units, synchronized via DIR/OE handshaking. Use Value: Eliminates discrete level shifters and reduces BOM count by 3+ components per channel while maintaining <7 ns timing integrity. |
Use Scenario: Routing AES3, I²S, or TDM audio streams between DSPs, ADCs, and DACs operating at different supply voltages. IC Role / Device Role / Timing Role: Voltage-tolerant bus transceiver enabling clean signal handoff without introducing jitter or ground bounce. Use Value: Prevents audible artifacts caused by output ringing; supports 192 kHz sample rates with deterministic propagation delay. |
| Smart Appliance Control Panels | Video Signage Display Interfaces |
|
Use Scenario: Interfacing touch controller ICs (3.3 V) to main application processors (5 V) in refrigerator or oven HMI subsystems. IC Role / Device Role / Timing Role: Direction-controlled data conduit for button press events, display updates, and status reporting. Use Value: Enables single-chip voltage translation across 16-bit parallel bus, reducing layout complexity and ESD vulnerability. |
Use Scenario: Driving LVDS or TTL-based video timing signals from media players to LED display driver boards in retail signage. IC Role / Device Role / Timing Role: Bus isolator that prevents backfeed during hot-plug events and maintains signal integrity under variable load. Use Value: Ensures glitch-free screen initialization and eliminates black-screen artifacts during power cycling of display modules. |
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 | Lower VCC range (1.65–3.6 V); 3.3 V only; faster tpd (5.3 ns @ 3.3 V) | Not suitable for 5 V bus interfacing; requires external level shifters for mixed-voltage systems | Select when system is fully 3.3 V and speed >7 ns is required; avoid if 5 V compatibility needed. |
| SN74AHCT245 | TTL-compatible inputs (VIH = 2 V min); fixed 4.5–5.5 V operation; higher drive (±24 mA @ 5 V) | Cannot accept 6 V inputs; lacks 2–6 V flexibility; better for legacy 5 V-only designs | Choose for strict TTL-level compatibility and maximum noise immunity in 5 V industrial backplanes. |
Compared with SN74LVC245A and SN74AHCT245, the SN74AC245RKSR uniquely balances wide supply range, 6 V input tolerance, and industrial temperature support-making it the only option among the three for robust mixed-voltage bus bridging without auxiliary components.
Availability
SN74AC245RKSR is available at Aetrix Electronics and suitable for factory automation I/O expansion, pro audio digital signal routing, and smart appliance control panels requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SN74AC245RKSR 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 90 years of innovation in industrial, automotive, and communications markets.
The SN74AC245RKSR belongs to TI's AC-series advanced CMOS logic family, engineered for low-noise, mixed-voltage bus interfacing in harsh industrial environments where reliability and voltage flexibility are critical.
FAQ
What is the maximum operating voltage for SN74AC245RKSR inputs?
The SN74AC245RKSR inputs tolerate voltages up to 6 V regardless of VCC level, allowing direct connection to 5 V logic signals even when powered from 3.3 V. This eliminates external level-shifting circuitry in mixed-voltage systems and is confirmed in Section 5.3 (Recommended Operating Conditions) and Section 5.1 (Absolute Maximum Ratings) of the official TI datasheet SCAS461I.
Does SN74AC245RKSR support hot-swap isolation between buses?
Yes, SN74AC245RKSR supports hot-swap isolation via its OE (output enable) pin: asserting OE high places all A and B port pins in high-impedance state, electrically isolating both buses without disrupting power or signal integrity. This behavior is defined in Table 7-1 (Function Table) and Section 7.1 (Overview) of the TI datasheet.
What is the thermal resistance (RθJA) of SN74AC245RKSR in its VQFN package?
The SN74AC245RKSR in the RKS (VQFN-20) package has a junction-to-ambient thermal resistance of 67.7°C/W, as specified in Section 5.4 (Thermal Information) of the TI datasheet SCAS461I. This value assumes standard JEDEC 2-layer board conditions and enables reliable operation at full output current in compact industrial PCB layouts.
Can SN74AC245RKSR be used in 3.3 V-only systems?
Yes, SN74AC245RKSR operates reliably at 3.3 V (within its 2–6 V VCC range), delivering ≤9 ns propagation delay and ±12 mA output drive per pin at that voltage. Its input thresholds scale with VCC, ensuring clean logic recognition in pure 3.3 V domains - verified in Section 5.6 (Switching Characteristics, VCC = 3.3 V).
How does the DIR pin control data flow direction in SN74AC245RKSR?
In SN74AC245RKSR, the DIR pin determines real-time bus direction: DIR low enables data transmission from B bus to A bus; DIR high enables A-to-B flow. This function is independent of OE and is validated in the functional truth table (Table 7-1) and logic diagram (Figure 4-3) of the TI datasheet SCAS461I.
SN74AC245RKSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AC
- 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:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 20-VQFN (2.5x4.5)
SN74AC245RKSR FAQ
1.How can I place an order for SN74AC245RKSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AC245RKSR 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 SN74AC245RKSR reliable?
The price and inventory of SN74AC245RKSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AC245RKSR is usually 5 days.
3.What payment methods are accepted for SN74AC245RKSR?
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Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AC245RKSR?
SN74AC245RKSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AC245RKSR 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 SN74AC245RKSR?
For technical support, including SN74AC245RKSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AC245RKSR requirements.
6.How does Aetrix verify that SN74AC245RKSR is sourced from the original manufacturer or authorized distributors?
All SN74AC245RKSR 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 SN74AC245RKSR meets industry standards.
7.What is the process for return or replacement of SN74AC245RKSR?
All SN74AC245RKSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AC245RKSR, 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 SN74AC245RKSR part is unused and in its original packaging.
Return procedure for SN74AC245RKSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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