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Texas Instruments SN74AHC245PW
- Part No.:
- SN74AHC245PW
- Manufacturer:
- Texas Instruments
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74AHC245PW.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,225
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Product details
Overview
SN74AHC245PW from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous two-way data bus communication between 3.3 V and 5 V systems. It operates from 2 V to 5.5 V, supports bidirectional data flow via DIR control, and features output enable (OE) for bus isolation. Used in PC motherboard I/O expansion and server memory subsystems where voltage-level translation and low-noise signal integrity are critical.
For engineers reviewing the SN74AHC245PW datasheet, SN74AHC245PW pinout, SN74AHC245PW application, or SN74AHC245PW equivalent, key selection criteria include its 20-pin TSSOP package, ±8 mA drive strength at 5 V, 4.5 ns typical propagation delay (VCC = 5 V, CL = 15 pF), overvoltage-tolerant inputs up to 5.5 V, and thermal resistance RθJA = 122.3 °C/W - all essential for embedded interface design and legacy-to-modern bus bridging.
Technical Context
The SN74AHC245PW implements dual-rail CMOS logic with independent A- and B-side I/O banks, enabling flexible direction control per channel via a single DIR input. Its output-enable architecture provides high-impedance isolation when OE is high, supporting hot-swap and power-down modes without bus contention.
It delivers deterministic timing behavior across supply voltages: tPLH/tPHL ≤ 6.5 ns at VCC = 5 V (CL = 15 pF), and maintains noise immunity via slow edge rates (Δt/Δv = 20 ns/V at 5 V), minimizing overshoot/undershoot on PCB traces in mixed-voltage environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2 V to 5.5 V - enables interoperability between 3.3 V microcontrollers and 5 V peripherals without level shifters. |
| IO Drive Strength | ±8 mA at VCC = 5 V - sufficient for driving standard TTL loads and short PCB traces without external buffers. |
| Propagation Delay | 4.0 ns (min) to 6.5 ns (max) at VCC = 5 V, CL = 15 pF - ensures tight timing margins in high-speed parallel bus applications. |
| Input Voltage Tolerance | Up to 5.5 V regardless of VCC - allows safe interfacing of 5 V signals into 3.3 V domains without clamping diodes. |
| Output Enable Latency | tPZH/tPLZ ≤ 10 ns at VCC = 5 V, CL = 15 pF - guarantees rapid bus isolation during dynamic reconfiguration. |
| Thermal Resistance | RθJA = 122.3 °C/W (TSSOP-20) - defines maximum power dissipation under natural convection for thermal layout planning. |
Pinout & Package
TSSOP-20 (PW) package: 6.50 mm × 6.40 mm body size, 0.65 mm lead pitch, surface-mount, RoHS-compliant, moisture sensitivity level 1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DIR (Pin 1) | Direction Control Input | Low = B→A data flow; High = A→B data flow - determines real-time bus directionality for full-duplex operation. |
| OE (Pin 19) | Output Enable Input | Low = active transceiver; High = 3-state isolation - prevents bus contention during reset or sleep states. |
| A1–A8 (Pins 2–9) | Port A I/O | Bidirectional data lines tied to one bus segment (e.g., microcontroller side); tolerate 5.5 V inputs at any VCC. |
| B1–B8 (Pins 11–18) | Port B I/O | Bidirectional data lines tied to second bus segment (e.g., peripheral side); electrically identical to Port A. |
| VCC (Pin 20) | Power Supply | Single-supply rail powering both logic core and I/O drivers; requires local 0.1 µF bypass capacitor. |
| GND (Pin 10) | Ground Reference | Common return path for all internal circuitry and I/O current; must be low-impedance connection to system ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| Voltage-Level Translation | Supports down-translation from 5 V to 3.3 V systems via overvoltage-tolerant inputs - eliminates need for discrete level shifters in mixed-supply designs. |
| Slow Edge Rate Control | Δt/Δv = 20 ns/V at 5 V - reduces EMI and signal ringing on long traces, improving signal integrity without external damping resistors. |
| Bus Isolation Capability | High-impedance 3-state outputs when OE = high - enables safe hot-plug insertion and multi-master arbitration on shared buses. |
| Latch-up Immunity | Exceeds 250 mA per JESD17 - ensures robust operation in noisy industrial environments with transient coupling. |
| Wide Operating Temperature | –40 °C to +125 °C ambient range - qualified for automotive under-hood and industrial control applications requiring extended thermal stability. |
Applications
| PC Motherboard I/O Expansion | Server Memory Subsystem Bridging |
|---|---|
Use Scenario: Connecting legacy ISA or LPC peripherals to modern low-voltage chipset interfaces on desktop motherboards. IC Role / Device Role / Timing Role: Bidirectional voltage-translating bus transceiver managing data flow between 5 V legacy devices and 3.3 V host controllers. Use Value: Eliminates discrete level-shifting components while maintaining <6.5 ns propagation delay for timing-critical control signals like SMCLK or LDRQ#. | Use Scenario: Interfacing DDR SDRAM command/address buses with baseboard management controllers (BMC) operating at different supply rails. IC Role / Device Role / Timing Role: Isolatable octal transceiver enabling BMC access to memory configuration registers without disrupting main CPU traffic. Use Value: OE-controlled 3-state operation prevents bus contention during BMC firmware updates, ensuring uninterrupted memory operation. |
| Industrial PLC Backplane Interface | Wearable Health Sensor Hub |
Use Scenario: Coupling modular I/O modules (5 V) to a 3.3 V ARM-based controller in programmable logic controller backplanes. IC Role / Device Role / Timing Role: Direction-controlled bus bridge synchronizing sensor data acquisition and actuator command distribution across voltage domains. Use Value: DIR pin enables dynamic reversal of data flow for half-duplex protocols like Modbus RTU, reducing component count versus dual unidirectional solutions. | Use Scenario: Aggregating analog front-end sensor data (ECG, SpO₂) from multiple 5 V analog ICs into a 3.3 V Bluetooth SoC in compact wearable form factors. IC Role / Device Role / Timing Role: Low-power octal transceiver translating sensor register reads/writes while minimizing PCB area via TSSOP-20 footprint. Use Value: 122.3 °C/W RθJA and 4 µA ICC allow continuous operation within thermally constrained enclosures without forced cooling. |
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 | Lower VCC range (1.65–3.6 V), higher speed (tPD = 3.8 ns @ 3.3 V), but no 5.5 V input tolerance. | Suitable only for pure 3.3 V systems; cannot replace SN74AHC245PW in 5 V–3.3 V translation roles. | Select when interfacing exclusively between 3.3 V domains and lower propagation delay is prioritized over voltage flexibility. |
| 74ALVC245MTCX | Same 1.65–3.6 V VCC range, 3.5 ns tPD, and 3.6 V max input voltage - lacks overvoltage capability and wider supply range. | Requires external clamping for 5 V signals; limited to low-voltage embedded applications without mixed-rail requirements. | Choose for cost-sensitive consumer electronics where 5 V compatibility is unnecessary and board space is highly constrained. |
Compared with SN74LVC245APWR and 74ALVC245MTCX, the SN74AHC245PW uniquely supports 2–5.5 V operation and 5.5 V-tolerant inputs - making it the only viable option for direct 5 V ↔ 3.3 V bus bridging without additional protection circuitry.
Availability
SN74AHC245PW is available at Aetrix Electronics and suitable for PC motherboard I/O expansion, server memory subsystem bridging, and industrial PLC backplane interface applications requiring stable component supply and long-term obsolescence management.
Supply support for SN74AHC245PW 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 interface technologies.
The SNx4AHC245 family was engineered for robust bidirectional bus interfacing in mixed-voltage computing and industrial systems, emphasizing voltage translation, noise resilience, and latch-up immunity across extended temperature ranges.
FAQ
What is the maximum input voltage rating for SN74AHC245PW, and does it depend on VCC?
The SN74AHC245PW supports input voltages up to 5.5 V on all A- and B-side pins, regardless of the applied VCC value (2 V to 5.5 V). This overvoltage tolerance enables safe interfacing of 5 V signals into 3.3 V systems without external clamping. The specification is explicitly confirmed in Section 5.3 (Recommended Operating Conditions) and Table 4-1 (Pin Functions) of the official TI datasheet SCLS230N.
Can SN74AHC245PW operate reliably at 2.5 V supply, and what performance trade-offs occur?
Yes, SN74AHC245PW is fully specified down to 2 V VCC and operates reliably at 2.5 V. At this voltage, output drive strength drops to ±4 mA (per Section 5.3), and propagation delay increases to ≤10 ns (Section 5.6), while input thresholds scale proportionally (VIH = 1.75 V, VIL = 0.75 V). These values are measured and guaranteed across –40 °C to +125 °C per TI's production test limits.
Is SN74AHC245PW pin-compatible with other packages in the SN74AHC245 family, such as SOIC or VSSOP?
No - SN74AHC245PW uses the TSSOP-20 (PW) package with 0.65 mm lead pitch and 6.50 mm × 6.40 mm body size. While all SN74AHC245 variants share identical pin functions and numbering (e.g., DIR on Pin 1, OE on Pin 19), mechanical dimensions, thermal characteristics, and soldering profiles differ significantly across packages (SOIC-DW, VSSOP-DGS, TVSOP-DGV). PCB layout must match the specific PW footprint.
How does the DIR pin control data direction, and what happens when OE is asserted high?
When OE is low, DIR = low enables B→A data flow; DIR = high enables A→B flow. When OE is high, all A- and B-side outputs enter high-impedance state regardless of DIR state - effectively isolating both buses. This behavior is defined in Table 7-1 (Function Table) and verified in functional testing per TI's production qualification standards.
What is the recommended bypass capacitor configuration for SN74AHC245PW in a high-density PCB layout?
Texas Instruments recommends a 0.1 µF ceramic capacitor placed as close as possible to the VCC pin (Pin 20), with short, low-inductance traces to GND (Pin 10). For systems with multiple power domains or high-frequency noise, paralleling a 1 µF capacitor is acceptable. Layout guidance is provided in Section 8.4.2 and Figure 8-3 of the SN74AHC245 datasheet.
SN74AHC245PW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHC
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- 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-TSSOP
SN74AHC245PW FAQ
1.How can I place an order for SN74AHC245PW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHC245PW 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 SN74AHC245PW reliable?
The price and inventory of SN74AHC245PW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHC245PW is usually 5 days.
3.What payment methods are accepted for SN74AHC245PW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHC245PW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHC245PW?
SN74AHC245PW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHC245PW 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 SN74AHC245PW?
For technical support, including SN74AHC245PW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHC245PW requirements.
6.How does Aetrix verify that SN74AHC245PW is sourced from the original manufacturer or authorized distributors?
All SN74AHC245PW 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 SN74AHC245PW meets industry standards.
7.What is the process for return or replacement of SN74AHC245PW?
All SN74AHC245PW units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHC245PW, 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 SN74AHC245PW part is unused and in its original packaging.
Return procedure for SN74AHC245PW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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