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Texas Instruments SN74AHC245RKSR
- Part No.:
- SN74AHC245RKSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-VFQFN Exposed Pad
- Datasheet:
-
SN74AHC245RKSR.pdf
- Description:
- OCTAL BUS TRANSCEIVERS WITH TRI-
- Quantity:
- Payment:
- Shipping:
Inventory:3,000
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Product details
Overview
SN74AHC245RKSR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between two 8-bit buses. It operates from 2 V to 5.5 V, supports 5-V-to-3.3-V voltage translation, and features 20-pin VQFN (RKS) packaging with thermal pad. Used in server backplanes and embedded microcontroller interfaces requiring level-shifting isolation.
For engineers reviewing the SN74AHC245RKSR datasheet, SN74AHC245RKSR pinout, SN74AHC245RKSR application, or SN74AHC245RKSR equivalent, key selection criteria include its 5.5-V tolerant inputs, 8 ns max propagation delay at 5 V, ±25 mA output drive, 3-state control via DIR/OE, and compact 4.5 mm × 2.5 mm VQFN package with exposed thermal pad.
Technical Context
The SN74AHC245RKSR implements dual-directional bus control using a single DIR input to select A→B or B→A data flow, while OE enables/disables all outputs simultaneously into high-impedance state. Its CMOS AHC logic family ensures low static current (4 µA typical ICC) and rail-to-rail output swing across 2–5.5 V supply range.
It supports mixed-voltage system interfacing: inputs tolerate up to 5.5 V regardless of VCC, enabling robust down-translation from 5 V domains to 3.3 V microcontrollers. The VQFN-RKS package includes an exposed thermal pad for enhanced thermal dissipation (RθJB = 40.4 °C/W), critical for sustained operation in dense PCB layouts.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2 V to 5.5 V - Enables interoperability across 2.5 V, 3.3 V, and 5 V logic domains without level shifters. |
| Propagation Delay (tPLH/tPHL) | 4 ns (min) / 6.5 ns (max) at VCC = 5 V, CL = 15 pF - Supports >100 MHz bus toggle rates in short-trace applications. |
| Output Drive | ±8 mA at VCC = 5 V - Sufficient to drive standard CMOS loads and moderate PCB trace capacitance without external buffers. |
| Input Voltage Tolerance | Up to 5.5 V on all I/O pins - Allows safe connection to 5 V sources even when VCC = 3.3 V, eliminating need for external clamping. |
| Quiescent Current (ICC) | 4 µA typical at VCC = 5.5 V - Minimizes standby power in battery-backed or energy-sensitive systems. |
| ESD Rating | 1500 V HBM, 2000 V CDM - Meets industrial-grade handling requirements without special ESD precautions during assembly. |
| Operating Temperature | –40 °C to +125 °C - Qualified for extended-temperature industrial and automotive under-hood applications. |
Pinout & Package
The SN74AHC245RKSR uses a 20-pin VQFN package (RKS) with 4.5 mm × 2.5 mm body size and an exposed thermal pad on the bottom for improved heat conduction to the PCB ground plane.
| 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 direction without clock or timing constraints. |
| 2–9 (A1–A8) | Port A bidirectional I/O | Connects to source bus (e.g., microcontroller); driven by internal transistors with 3-state capability when OE = high. |
| 10 (GND) | Ground reference | Primary return path for all signals and power; must be low-impedance and tied directly to PCB ground plane. |
| 11–18 (B1–B8) | Port B bidirectional I/O | Connects to destination bus (e.g., peripheral ASIC); electrically isolated from Port A when OE = high. |
| 19 (OE) | Output enable input | Active-low control: Low = transceivers enabled; High = all A/B pins enter high-impedance state - Enables bus sharing and hot-swap isolation. |
| 20 (VCC) | Power supply | Supplies core logic and I/O drivers; requires local 0.1 µF ceramic bypass capacitor placed within 2 mm of pin. |
| Thermal Pad | Thermal and electrical ground | Must be soldered to solid PCB ground plane area to achieve RθJB = 40.4 °C/W and ensure reliable thermal performance. |
Key Features
| Feature | Design Value |
|---|---|
| 5.5-V tolerant inputs | Enables direct interface to legacy 5 V logic without external voltage translators or resistive dividers. |
| Slow edge-rate control | Reduces output ringing and EMI in high-speed traces, improving signal integrity on FR-4 PCBs without added termination. |
| High-impedance power-up state | OE defaults to high-impedance on power ramp; prevents bus contention during system initialization when OE is pulled up externally. |
| Low dynamic power consumption | 14 pF typical power dissipation capacitance (Cpd) minimizes switching current at 1 MHz, reducing total system power. |
| VQFN thermal pad integration | Exposed pad lowers junction-to-board thermal resistance to 40.4 °C/W, supporting continuous operation at full drive in compact enclosures. |
Applications
| Server Backplane Interface | Industrial PLC I/O Module |
|---|---|
|
Use Scenario: Isolating and translating control signals between 5 V FPGA configuration bus and 3.3 V management microcontroller in a 1U rack server. IC Role / Device Role / Timing Role: Bidirectional level-shifting transceiver managing command/status exchange with no timing overhead. Use Value: Eliminates discrete level shifters and reduces BOM count by 8× per bus, while maintaining <6.5 ns propagation delay for real-time response. |
Use Scenario: Interfacing a 3.3 V ARM-based controller to legacy 5 V sensor/actuator modules in modular automation hardware. IC Role / Device Role / Timing Role: Asynchronous bus isolator enabling hot-swap-safe field I/O expansion without bus contention. Use Value: ±25 mA drive per channel supports direct connection to optocoupler inputs and relay drivers, avoiding buffer ICs. |
| Wearable Health Hub | Network Switch Control Plane |
|
Use Scenario: Connecting low-power 3.3 V BLE SoC to 5 V display driver and biometric sensor subsystems in a compact wearable device. IC Role / Device Role / Timing Role: Voltage-translating bus transceiver with ultra-low ICC (4 µA) for battery runtime optimization. Use Value: 4.5 mm × 2.5 mm VQFN footprint saves >40% board area vs. SOIC alternatives, critical for space-constrained wearables. |
Use Scenario: Managing configuration and status communication between 5 V switch fabric ASIC and 3.3 V baseboard management controller (BMC). IC Role / Device Role / Timing Role: Isolated bidirectional data path with OE-controlled shutdown during firmware updates. Use Value: 1500 V HBM ESD rating ensures robustness in high-handling-volume manufacturing and field service environments. |
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; 5.5 V input tolerance retained but not rated for 5 V VCC operation. | Suitable only for 3.3 V-only systems; cannot replace SN74AHC245RKSR in 5 V supply rails or mixed 5 V/3.3 V domains. | Select when operating exclusively at 3.3 V and lower power is prioritized over 5 V compatibility. |
| 74AVCH245 | Supports 0.8–3.6 V VCC; higher speed (2.4 ns typ tPD at 3.3 V) but lower drive (±12 mA) and no 5 V tolerance on I/O pins. | Requires external level shifting for 5 V interfaces; optimized for ultra-low-voltage mobile SoC interconnects, not industrial backplanes. | Choose for sub-1 V logic domains or where 2.4 ns speed outweighs 5 V interoperability needs. |
Compared with SN74LVC245A and 74AVCH245, the SN74AHC245RKSR uniquely supports full 2–5.5 V operation with 5.5 V-tolerant I/O, making it the only option for direct 5 V-to-3.3 V bidirectional translation without auxiliary circuitry.
Availability
SN74AHC245RKSR is available at Aetrix Electronics and suitable for server backplanes, industrial PLC I/O modules, and wearable health hubs requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for SN74AHC245RKSR 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 decades of expertise in logic interface ICs and industrial-grade reliability validation.
The SN74AHC245RKSR belongs to TI's AHC logic family, engineered for robust mixed-voltage system interfacing in servers, networking equipment, and industrial automation where signal integrity, thermal efficiency, and wide supply range are critical.
FAQ
What is the maximum operating voltage for SN74AHC245RKSR?
The SN74AHC245RKSR supports a supply voltage range of 2 V to 5.5 V. Its inputs are rated for up to 5.5 V regardless of VCC, allowing safe operation in mixed-voltage systems. Exceeding 5.5 V on any pin violates absolute maximum ratings and may cause permanent damage to the SN74AHC245RKSR.
Does SN74AHC245RKSR support 5 V to 3.3 V level translation?
Yes, the SN74AHC245RKSR supports bidirectional 5 V to 3.3 V level translation. Its inputs tolerate up to 5.5 V at any valid VCC, and outputs swing rail-to-rail. When VCC = 3.3 V, the SN74AHC245RKSR accepts 5 V inputs and drives 3.3 V-compatible loads - no external components required.
What is the purpose of the thermal pad on the SN74AHC245RKSR package?
The exposed thermal pad on the SN74AHC245RKSR's VQFN package provides a low-resistance thermal path from the die to the PCB ground plane. Proper soldering of this pad achieves RθJB = 40.4 °C/W, essential for maintaining junction temperature within limits during sustained ±8 mA output loading.
How does the DIR pin control data flow in SN74AHC245RKSR?
The DIR pin on the SN74AHC245RKSR determines real-time bus direction: DIR = Low enables B→A data transfer; DIR = High enables A→B transfer. This asynchronous control requires no clock or setup/hold timing, making the SN74AHC245RKSR ideal for simple, deterministic bus bridging.
Can SN74AHC245RKSR outputs be left floating when OE is high?
No - when OE is high, all A and B pins enter high-impedance state but remain electrically connected to internal circuitry. Leaving them unconnected risks noise coupling and undefined logic states. For robust design, unused A/B pins should be terminated to VCC or GND, especially in noisy industrial environments.
SN74AHC245RKSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHC
- 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:
- 2V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-VQFN (2.5x4.5)
SN74AHC245RKSR FAQ
1.How can I place an order for SN74AHC245RKSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHC245RKSR 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 SN74AHC245RKSR reliable?
The price and inventory of SN74AHC245RKSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHC245RKSR is usually 5 days.
3.What payment methods are accepted for SN74AHC245RKSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHC245RKSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHC245RKSR?
SN74AHC245RKSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHC245RKSR 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 SN74AHC245RKSR?
For technical support, including SN74AHC245RKSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHC245RKSR requirements.
6.How does Aetrix verify that SN74AHC245RKSR is sourced from the original manufacturer or authorized distributors?
All SN74AHC245RKSR 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 SN74AHC245RKSR meets industry standards.
7.What is the process for return or replacement of SN74AHC245RKSR?
All SN74AHC245RKSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHC245RKSR, 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 SN74AHC245RKSR part is unused and in its original packaging.
Return procedure for SN74AHC245RKSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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