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Texas Instruments SN74AHCT245RKSR
- Part No.:
- SN74AHCT245RKSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-VFQFN Exposed Pad
- Datasheet:
-
SN74AHCT245RKSR.pdf
- Description:
- OCTAL BUS TRANSCEIVERS WITH TRI-
- Quantity:
- Payment:
- Shipping:
Inventory:2,864
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Product details
Overview
SN74AHCT245RKSR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data bus communication between 3.3 V and 5 V domains. It operates from 4.5 V to 5.5 V, features TTL-compatible inputs (VIH = 2 V, VIL = 0.8 V), supports ±8 mA output drive, and delivers tPLH/tPHL ≤ 10 ns (CL = 15 pF) - enabling reliable level translation in microcontroller I/O expansion and memory interface applications.
For engineers reviewing the SN74AHCT245RKSR datasheet, SN74AHCT245RKSR pinout, SN74AHCT245RKSR application, or SN74AHCT245RKSR equivalent, this page provides verified package mapping (RKS VQFN-20), functional mode truth table, thermal resistance (RθJA = 67.7 °C/W), latch-up immunity (>250 mA), and ESD ratings (HBM ±2000 V) critical for industrial control and embedded system design.
Technical Context
The SN74AHCT245RKSR implements dual-directional bus control via DIR input and 3-state output enable via OE, allowing configurable A→B or B→A data flow while isolating buses when OE is high. Its CMOS design with slow edge rates minimizes output ringing and overshoot on light loads.
It accepts 3.3 V logic inputs at 5 V VCC (VIH = 2 V), enabling robust 3.3 V-to-5 V voltage translation without external level shifters. All 16 I/O pins (A1–A8, B1–B8) are bidirectional and overvoltage tolerant up to 5.5 V, supporting hot-swap and mixed-voltage system interoperability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - ensures compatibility with standard 5 V logic rails and tolerance to supply ripple. |
| VIH / VIL | 2 V / 0.8 V - guarantees TTL-level input compatibility and reliable interfacing with legacy 3.3 V microcontrollers. |
| IOH / IOL | –8 mA / 8 mA - sufficient drive strength for fan-out to multiple CMOS loads without signal degradation. |
| tPLH / tPHL | ≤10 ns (CL = 15 pF) - enables operation in high-speed digital systems up to ~50 MHz clock-equivalent data rates. |
| RθJA | 67.7 °C/W - low thermal resistance for RKS VQFN-20 package supports sustained operation at full load in compact industrial PCBs. |
| ESD HBM | ±2000 V - meets JEDEC JS-001 for handling robustness in automated assembly and field service environments. |
| Latch-up | >250 mA per JESD17 - prevents destructive latch-up during transient overvoltage events on I/O lines. |
Pinout & Package
The SN74AHCT245RKSR is housed in a 4.50 mm × 2.50 mm RKS VQFN-20 package with exposed thermal pad, optimized for space-constrained industrial and automotive control modules.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DIR (Pin 1) | Direction control input | Low = B→A data transfer; High = A→B data transfer - determines real-time bus flow direction. |
| OE (Pin 19) | Output enable input | Low = active transceiver; High = all A/B I/Os enter high-impedance state - enables bus isolation during reset or standby. |
| A1–A8 (Pins 2–9) | Bidirectional I/O port A | Connects to local controller or processor bus; tolerates 0–5.5 V input regardless of VCC - simplifies mixed-voltage routing. |
| B1–B8 (Pins 11–18) | Bidirectional I/O port B | Interfaces to peripheral or memory bus; identical electrical behavior to A-side - supports symmetrical bidirectional data exchange. |
| VCC (Pin 20) | Positive supply | Must be bypassed with 0.1 µF capacitor near pin - suppresses switching noise and maintains stable 5 V rail under dynamic load. |
| GND (Pin 10) | Ground reference | Common return path for all signals and power - requires low-inductance connection to minimize ground bounce. |
| Thermal Pad | Case ground / heat sink | Must be soldered to PCB copper pour - essential for achieving rated RθJA = 67.7 °C/W and long-term reliability. |
Key Features
| Feature | Design Value |
|---|---|
| TTL-compatible inputs | VIH = 2 V, VIL = 0.8 V - eliminates need for external pull-ups or level translators when interfacing with 3.3 V MCU GPIOs. |
| Slow edge rate control | Minimizes output ringing and EMI in unterminated traces - critical for noise-sensitive industrial sensor interfaces. |
| Overvoltage-tolerant I/Os | Accepts inputs up to 5.5 V independent of VCC - enables safe hot-plug operation and mixed-supply system resilience. |
| High-impedance isolation | OE-controlled 3-state outputs prevent bus contention during power-up/down or controller reset sequences. |
| Low quiescent current | ICC ≤ 40 µA - reduces standby power in battery-backed or energy-conscious embedded designs. |
Applications
| Industrial PLC I/O Expansion | Microcontroller Memory Interface |
|---|---|
Use Scenario: Expanding GPIO count of ARM Cortex-M4-based PLC CPU to drive discrete I/O modules via parallel bus. IC Role / Device Role / Timing Role: Bidirectional data bridge between 3.3 V MCU bus and 5 V opto-isolated output stage, synchronized by DIR/OE control signals. Use Value: Enables direct 3.3 V-to-5 V translation without external biasing, reducing BOM count and layout area while maintaining <10 ns propagation delay. | Use Scenario: Interfacing an FPGA configured as a memory controller to external SRAM operating at 5 V. IC Role / Device Role / Timing Role: Level-shifting transceiver placed between FPGA's 3.3 V I/O bank and SRAM address/data bus, with DIR tied to FPGA write-enable. Use Value: Eliminates need for discrete MOSFET translators; supports 50 MHz burst read/write cycles with guaranteed timing margins per tPLH/tPHL specs. |
| Automotive Body Control Module | Test Equipment Digital Pattern Generator |
Use Scenario: Isolating CAN microcontroller I/O from 5 V sensor interface circuitry in body control unit. IC Role / Device Role / Timing Role: Bus isolator activated during MCU reset (OE high), preventing spurious writes to LIN-connected peripherals. Use Value: Prevents bus contention and undefined states during cold boot; latch-up immunity >250 mA protects against load-dump transients. | Use Scenario: Generating programmable 5 V digital stimulus patterns from 3.3 V pattern generator ASIC. IC Role / Device Role / Timing Role: Output driver translating internal test vectors to 5 V logic levels, with OE synchronized to pattern frame start. Use Value: Delivers clean 5 V waveforms with controlled slew rate - reduces false triggering on DUT inputs and improves test repeatability. |
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; no TTL input compatibility | Suitable only for pure 3.3 V systems; cannot translate 3.3 V → 5 V | Select when operating exclusively at 3.3 V and lower power is prioritized over voltage translation. |
| 74AHCT245 (Nexperia) | Identical logic function, pinout, and DC specs; minor differences in AC timing (tPLH/tPHL max 11 ns vs 10 ns) | Drop-in replacement in most 5 V designs; same RKS VQFN-20 footprint available | Choose for second-source assurance where TI supply continuity is a concern; verify timing margin in high-speed paths. |
Compared with SN74LVC245A and 74AHCT245, the SN74AHCT245RKSR uniquely combines 5 V operation, TTL input compatibility, and RKS VQFN-20 packaging - making it the only option among the three that supports 3.3 V-to-5 V translation in space-constrained industrial PCBs without redesign.
Availability
SN74AHCT245RKSR is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, automotive body control modules, microcontroller memory interfaces, and test equipment digital pattern generation requiring stable component supply across extended temperature ranges (–40°C to +125°C).
Supply support for SN74AHCT245RKSR 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 SN74AHCT245RKSR belongs to TI's AHCT logic family, engineered for robust 5 V mixed-signal interfacing with emphasis on voltage translation, noise immunity, and thermal efficiency in harsh-environment applications.
FAQ
What is the maximum operating temperature for the SN74AHCT245RKSR?
The SN74AHCT245RKSR is rated for continuous operation from –40°C to +125°C ambient temperature, validated per its Recommended Operating Conditions table. This extended range supports deployment in under-hood automotive ECUs and industrial motor drives where thermal management is constrained. The RKS VQFN package's RθJA of 67.7 °C/W ensures junction temperature remains within safe limits even at full output loading.
Does the SN74AHCT245RKSR require external pull-up resistors on DIR or OE?
The SN74AHCT245RKSR does not require external pull-up resistors on DIR or OE for basic functionality, but OE should be tied to VCC through a pullup resistor during power-up to ensure outputs remain in high-impedance state until firmware initializes control logic. TI recommends a minimum resistor value determined by the driver's current-sinking capability - typically 10 kΩ suffices for most microcontroller-driven applications using the SN74AHCT245RKSR.
Can the SN74AHCT245RKSR be used for 5 V to 3.3 V level translation?
No, the SN74AHCT245RKSR is not designed for 5 V-to-3.3 V translation. Its outputs swing rail-to-rail (0 V to VCC), so when powered at 5 V, outputs reach 5 V - potentially damaging 3.3 V-only inputs. It supports only 3.3 V-to-5 V translation via TTL-compatible inputs (VIH = 2 V) accepting 3.3 V logic highs while operating at 5 V VCC. For bidirectional 5 V ↔ 3.3 V translation, a dedicated level shifter like TXB0108 is required instead of the SN74AHCT245RKSR.
What is the purpose of the exposed thermal pad on the SN74AHCT245RKSR package?
The exposed thermal pad on the SN74AHCT245RKSR's RKS VQFN-20 package serves as the primary heat dissipation path from the silicon die to the PCB. It must be soldered to a thermally conductive copper pour to achieve the specified RθJA of 67.7 °C/W. Omitting pad connection degrades thermal performance significantly - increasing junction temperature by >30°C under full load - and risks long-term reliability failure. TI documentation mandates this connection for all SN74AHCT245RKSR applications.
How does the SN74AHCT245RKSR handle unused inputs?
All unused inputs on the SN74AHCT245RKSR - including DIR and OE - must be actively driven to either VCC or GND to prevent floating states that cause increased ICC, erratic switching, or ESD susceptibility. TI explicitly warns against leaving inputs unconnected, especially in high-noise industrial environments. For OE, tying to VCC disables outputs; for DIR, tying to GND fixes A→B direction. Unused A/B I/O pins may float only if OE is asserted high, but best practice is to terminate them to avoid capacitive coupling noise - confirming guidance in the SN74AHCT245RKSR datasheet Section 9.4.1.
SN74AHCT245RKSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- 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:
- 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-VQFN (2.5x4.5)
SN74AHCT245RKSR FAQ
1.How can I place an order for SN74AHCT245RKSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT245RKSR 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 SN74AHCT245RKSR reliable?
The price and inventory of SN74AHCT245RKSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT245RKSR is usually 5 days.
3.What payment methods are accepted for SN74AHCT245RKSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT245RKSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHCT245RKSR?
SN74AHCT245RKSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT245RKSR 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 SN74AHCT245RKSR?
For technical support, including SN74AHCT245RKSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT245RKSR requirements.
6.How does Aetrix verify that SN74AHCT245RKSR is sourced from the original manufacturer or authorized distributors?
All SN74AHCT245RKSR 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 SN74AHCT245RKSR meets industry standards.
7.What is the process for return or replacement of SN74AHCT245RKSR?
All SN74AHCT245RKSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT245RKSR, 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 SN74AHCT245RKSR part is unused and in its original packaging.
Return procedure for SN74AHCT245RKSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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