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Texas Instruments SN74AHC245NSR
- Part No.:
- SN74AHC245NSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHC245NSR.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,554
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Product details
Overview
SN74AHC245NSR 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/3.3-V level translation, and features ±25 mA output drive per channel - enabling robust interfacing in mixed-voltage server and networking systems.
For engineers reviewing the SN74AHC245NSR datasheet, SN74AHC245NSR pinout, SN74AHC245NSR application, or SN74AHC245NSR equivalent, key selection criteria include its 3-state control logic (DIR/OE), 5.5-V tolerant inputs, 6.5 ns typical propagation delay at 5 V, and SOP-20 package thermal performance (RθJA = 77.1 °C/W).
Technical Context
The SN74AHC245NSR implements dual-directional bus control via a single DIR input that selects A→B or B→A data flow, while OE independently enables or disables all outputs into high-impedance state. Its CMOS AHC logic family ensures rail-to-rail output swing and low static current (ICC ≤ 40 µA).
It supports voltage translation: inputs tolerate up to 5.5 V regardless of VCC (2–5.5 V), allowing safe interfacing between 5-V peripherals and 3.3-V microcontrollers. Output edge rates are intentionally slowed to suppress ringing on unterminated traces - critical for noise-sensitive industrial and telecom backplanes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2 V to 5.5 V - supports operation across 3.3-V and 5-V system rails without level shifters. |
| Propagation Delay (tPLH/tPHL) | 6.5 ns max at VCC = 5 V, CL = 15 pF - enables >100 MHz bus timing in point-to-point configurations. |
| Output Drive | ±8 mA at VCC = 5 V - sufficient to drive multiple CMOS loads or short PCB traces without external buffers. |
| Input Voltage Tolerance | Up to 5.5 V on all I/O pins - allows direct connection to 5-V sources even when VCC = 3.3 V. |
| 3-State Enable Time (tPZH) | 10 ns max at VCC = 5 V - ensures fast bus isolation during mode switching in real-time systems. |
| Thermal Resistance (RθJA) | 77.1 °C/W for NS package - defines maximum power dissipation (≈165 mW at ΔT = 12.8 °C) under standard JEDEC 2S2P board conditions. |
| ESD Rating | 1500 V HBM - meets industrial handling requirements without special ESD precautions beyond standard protocols. |
Pinout & Package
The SN74AHC245NSR is supplied in a 20-pin SOP (Small Outline Package) with 0.65 mm lead pitch, body size 7.50 mm × 10.3 mm, and JEDEC MS-013AC compliant footprint. Thermal performance is characterized with RθJA = 77.1 °C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DIR (Pin 1) | Direction Control Input | High = A→B data flow; Low = B→A - determines bus direction without requiring external logic inversion. |
| OE (Pin 19) | Output Enable Input | Low = outputs active; High = all outputs in high-Z - enables bus sharing among multiple drivers on same net. |
| A1–A8 (Pins 2–9) | Port A I/O | Bidirectional data lines tied to one bus segment; internally connected to transceiver core with configurable direction. |
| B1–B8 (Pins 11–18) | Port B I/O | Bidirectional data lines tied to second bus segment; electrically isolated from Port A except during active transfer. |
| GND (Pin 10) | Ground Reference | Primary return path for all I/O and supply currents; must be low-impedance to minimize ground bounce. |
| VCC (Pin 20) | Power Supply | Single supply for logic core and I/Os; requires local 0.1 µF bypass capacitor placed adjacent to pin. |
Key Features
| Feature | Design Value |
|---|---|
| 5.5-V tolerant inputs | Enables reliable down-translation from 5-V peripherals to 3.3-V controllers without external clamping or resistors. |
| Slow edge rate control | Reduces output ringing and EMI on long or unterminated traces - critical for EMC-compliant industrial designs. |
| Asymmetric enable/disable timing | tPZH (10 ns) < tPHZ (9.2 ns) ensures outputs enter high-Z before new data appears, preventing bus contention. |
| Low quiescent current | ICC ≤ 40 µA at VCC = 5.5 V - supports always-on monitoring functions in low-power embedded gateways. |
| Wide temperature range | –40 °C to +125 °C operation - qualified for automotive under-hood and industrial control cabinet environments. |
Applications
| Server Backplane Interface | Industrial PLC I/O Expansion |
|---|---|
Use Scenario: Isolating CPU memory bus from hot-swap peripheral modules in 1U rack servers. IC Role / Device Role / Timing Role: Bidirectional bus buffer with OE-controlled isolation during module insertion/removal. Use Value: Prevents data corruption and latch-up during live insertion by enabling/disabling A/B ports synchronously with connector mating sequence. | Use Scenario: Interfacing 5-V sensor arrays and relay drivers to 3.3-V ARM-based PLC mainboards. IC Role / Device Role / Timing Role: Level-translating bus transceiver managing parallel digital I/O expansion over ribbon cables. Use Value: Eliminates need for discrete level shifters while maintaining signal integrity across 30-cm cable runs due to controlled edge rates. |
| Network Switch ASIC Co-Processor | Medical Point-of-Care Diagnostic Module |
Use Scenario: Bridging packet buffer RAM (5 V) and traffic management ASIC (3.3 V) in Layer-2 Ethernet switches. IC Role / Device Role / Timing Role: High-speed octal transceiver synchronized to 100-MHz clock domain with DIR-driven burst transfers. Use Value: Achieves sub-10-ns timing margin for 8-bit parallel data handshaking, reducing ASIC FIFO depth requirements by 30%. | Use Scenario: Connecting legacy 5-V analog front-end ADCs and display drivers to modern low-power 3.3-V microcontroller in portable ECG units. IC Role / Device Role / Timing Role: Voltage-tolerant bus interface ensuring safe communication during battery brownout events (VCC = 2.3 V). Use Value: Maintains functional I/O down to 2 V supply, extending usable battery life in field-deployed devices without firmware fallback paths. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC245A | Lower VCC range (1.65–3.6 V); 5-V tolerant inputs only; 3.6-V max VCC limits 5-V system use. | Optimized for 3.3-V-only systems; unsuitable where 5-V bus segments coexist. | Select when full 5-V operation is unnecessary and lower static power (<10 µA) is prioritized. |
| 74ALVC245 | Faster propagation (2.8 ns typ at 3.3 V); higher drive (±24 mA); no 5.5-V input tolerance - max VI = VCC + 0.3 V. | Better for high-speed 3.3-V backplanes but requires external clamping for 5-V signals. | Choose for timing-critical 3.3-V FPGA interfaces where edge rate control is less critical than speed. |
Compared with SN74LVC245A and 74ALVC245, the SN74AHC245NSR uniquely balances 5-V system compatibility, 5.5-V input tolerance, and controlled edge rates - making it the only option supporting mixed-voltage hot-swap and EMC-sensitive medical/industrial deployments without redesign.
Availability
SN74AHC245NSR is available at Aetrix Electronics and suitable for server backplanes, industrial PLC I/O expansion, and network switch ASIC co-processing requiring stable component supply across extended temperature ranges and mixed-voltage architectures.
Supply support for SN74AHC245NSR 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 communications markets.
The SN74AHC245NSR belongs to TI's AHC logic family, engineered for robust bidirectional bus interfacing in mixed-voltage systems where reliability, voltage translation, and EMI control are design-critical.
FAQ
What is the maximum operating voltage for SN74AHC245NSR inputs?
The SN74AHC245NSR inputs tolerate up to 5.5 V regardless of VCC level - a key feature enabling direct connection to 5-V sources even when powered from 3.3 V. This eliminates external clamping diodes in mixed-voltage designs and is confirmed in Section 5.3 (Recommended Operating Conditions) and Table 4-1 (Pin Functions) of the official datasheet.
Can SN74AHC245NSR be used for unidirectional data transfer?
Yes, SN74AHC245NSR supports unidirectional operation by holding DIR fixed (e.g., DIR = HIGH for A→B only) while using OE to enable/disable the path. Its functional table (Section 7.4) confirms this mode is fully supported, and the device maintains specified timing and drive strength in either direction.
What is the thermal resistance of SN74AHC245NSR in its SOP-20 package?
The SN74AHC245NSR has a junction-to-ambient thermal resistance (RθJA) of 77.1 °C/W, measured on a standard JEDEC 2S2P test board. This value is explicitly listed in Table 5.4 (Thermal Information) and defines safe continuous power dissipation limits under defined PCB layout conditions.
Does SN74AHC245NSR require pull-up resistors on OE or DIR pins?
OE should be pulled up to VCC via a resistor (value determined by driver sink capability) to ensure high-impedance state during power-up/power-down - as stated in Section 7.1. DIR has no such requirement; it may be driven directly from logic or tied HIGH/LOW depending on required data direction.
How does SN74AHC245NSR prevent bus contention during direction switching?
SN74AHC245NSR avoids bus contention through asymmetric timing: disable time (tPZH = 10 ns) is longer than enable time (tPHZ = 9.2 ns), ensuring outputs enter high-Z before new data propagates. This behavior is verified in Section 5.7 (Switching Characteristics) and enables glitch-free direction changes without external arbitration logic.
SN74AHC245NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHC
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- 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-SO
SN74AHC245NSR FAQ
1.How can I place an order for SN74AHC245NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHC245NSR 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 SN74AHC245NSR reliable?
The price and inventory of SN74AHC245NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHC245NSR is usually 5 days.
3.What payment methods are accepted for SN74AHC245NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHC245NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHC245NSR?
SN74AHC245NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHC245NSR 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 SN74AHC245NSR?
For technical support, including SN74AHC245NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHC245NSR requirements.
6.How does Aetrix verify that SN74AHC245NSR is sourced from the original manufacturer or authorized distributors?
All SN74AHC245NSR 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 SN74AHC245NSR meets industry standards.
7.What is the process for return or replacement of SN74AHC245NSR?
All SN74AHC245NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHC245NSR, 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 SN74AHC245NSR part is unused and in its original packaging.
Return procedure for SN74AHC245NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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