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Texas Instruments SN74AHCT245PW
- Part No.:
- SN74AHCT245PW
- Manufacturer:
- Texas Instruments
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74AHCT245PW.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:407
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Product details
Overview
SN74AHCT245PW from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between 5 V buses. It operates from 4.5 V to 5.5 V, features TTL-compatible inputs (VIH = 2 V, VIL = 0.8 V), supports ±25 mA output drive per pin, and delivers typical propagation delay of 4.5 ns (CL = 15 pF) in A↔B direction - used in microcontroller-to-peripheral bus isolation and level translation.
For engineers reviewing the SN74AHCT245PW datasheet, SN74AHCT245PW pinout, SN74AHCT245PW application, or SN74AHCT245PW equivalent, key selection criteria include 20-pin TSSOP package compatibility, 3-state control via DIR/OE logic, 5 V supply operation, latch-up immunity (>250 mA), and ESD robustness (±2 kV HBM).
Technical Context
The SN74AHCT245PW implements dual-directional 8-bit data routing controlled by a single DIR input and enabled/disabled globally via OE. Its CMOS design with TTL-voltage-compatible inputs allows seamless interfacing with legacy 5 V logic while maintaining low power consumption (ICC ≤ 40 µA at 5.5 V). The device uses balanced output drivers and slow edge rates to minimize ringing on lightly loaded buses.
Functional modes are strictly defined by OE and DIR: when OE = L, data flows A→B (DIR = H) or B→A (DIR = L); when OE = H, all I/Os enter high-impedance state regardless of DIR. No internal pullups/pulldowns exist - external biasing of OE is required for defined power-up behavior.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures compatibility with standard 5 V systems and tolerance to rail droop during transient load. |
| Input Voltage Compatibility | TTL-level: VIH = 2 V min, VIL = 0.8 V max - enables direct connection to 3.3 V or 5 V logic without level shifters. |
| Output Drive | ±8 mA at VOH/VOL specs; ±25 mA absolute max - sufficient for driving multiple CMOS loads but requires bus contention avoidance. |
| Propagation Delay | 4.5 ns typ (A↔B, CL = 15 pF) - supports >100 MHz data rates in short-bus configurations. |
| ESD Rating | ±2000 V HBM - meets industrial handling requirements without additional protection circuitry. |
| Latch-up Immunity | >250 mA per JESD17 - prevents destructive latch-up under transient overcurrent conditions. |
| Operating Temperature | –40°C to +125°C - qualified for extended industrial environments including automotive under-hood proximity. |
Pinout & Package
TSSOP-20 (PW) package: 6.50 mm × 4.40 mm body, 0.65 mm pitch, exposed pad not present, RoHS-compliant NiPdAu lead finish, MSL Level-1 (260°C reflow unlimited).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DIR (Pin 1) | Direction control input | Active-High logic selects A→B data flow; DIR = L enables B→A - determines signal path polarity during active operation. |
| A1–A8 (Pins 2–9) | Port A bidirectional I/O | Connects to source bus (e.g., MCU data bus); high-impedance when OE = H or device powered down. |
| GND (Pin 10) | Ground reference | Primary return path for all I/O and supply currents; must be low-inductance connection to avoid noise coupling. |
| B8–B1 (Pins 11–18) | Port B bidirectional I/O | Connects to destination bus (e.g., peripheral interface); mirrors A-port state when enabled and directionally aligned. |
| OE (Pin 19) | Output enable input | Active-Low global enable - OE = H forces all A/B pins into 3-state; tie to VCC via pullup for safe power-up isolation. |
| VCC (Pin 20) | Positive supply | 5 V nominal supply; requires local 0.1 µF ceramic bypass capacitor placed within 3 mm of pin for stable switching. |
Key Features
| Feature | Design Value |
|---|---|
| TTL-compatible inputs | Accepts 0.8 V/2 V thresholds - eliminates need for external level translators when interfacing with legacy 5 V TTL or mixed-voltage systems. |
| Asymmetric 3-state control | Separate DIR and OE pins allow independent direction selection and bus isolation - enables dynamic reconfiguration without glitching. |
| Slow edge rate optimization | Controlled slew minimizes overshoot/undershoot on PCB traces - reduces EMI and eliminates need for series termination resistors in most layouts. |
| High noise immunity | VIH(D)/VIL(D) = 2 V / 0.8 V dynamic thresholds - maintains reliable switching in electrically noisy industrial environments. |
| Low static current | ICC ≤ 40 µA at 5.5 V - supports low-power standby modes in battery-backed or energy-sensitive applications. |
Applications
| Microcontroller Bus Expansion | Industrial I/O Module Interface |
|---|---|
|
Use Scenario: Expanding GPIO count of an ARM Cortex-M4 MCU by connecting parallel peripherals (ADCs, DACs, GPIO expanders) via shared 8-bit data bus. IC Role / Device Role / Timing Role: Bidirectional data bridge isolating MCU core from peripheral timing variations; DIR set statically, OE toggled per transaction. Use Value: Enables deterministic read/write handshaking without bus contention, leveraging 4.5 ns propagation to sustain >20 MB/s throughput over short traces. |
Use Scenario: Interfacing PLC CPU module (5 V) with isolated digital input/output cards operating at same rail but requiring galvanic separation via optocouplers or discrete buffers. IC Role / Device Role / Timing Role: Signal direction arbitrator and bus driver - OE synchronized with controller's address decode window to prevent backfeeding during card hot-swap. Use Value: Provides ±25 mA drive capability to overcome optocoupler CTR degradation over time, ensuring reliable logic-level transmission across decades of field operation. |
| Legacy System Data Translation | Test Equipment Signal Routing |
|
Use Scenario: Up-translating 3.3 V FPGA configuration data to 5 V EEPROM programming interface during system boot. IC Role / Device Role / Timing Role: Unidirectional level translator (A→B mode) with OE held low; DIR fixed to enable A→B flow only. Use Value: Eliminates need for discrete MOSFET-based translators - reduces BOM count and layout area while guaranteeing VIH = 2 V compliance at 3.3 V input swing. |
Use Scenario: Automated test fixture routing DUT signals between multiple instrument channels (logic analyzer, pattern generator, scope) using software-controlled bus switches. IC Role / Device Role / Timing Role: Reconfigurable signal path selector - DIR and OE driven by microcontroller to establish dynamic A↔B or isolated states per test step. Use Value: Achieves sub-10 ns channel switching with no external timing components, enabling precise synchronization of stimulus/response measurements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC245APW | Lower VCC range (1.65–3.6 V), 3.3 V native logic; 3.5 ns tPD; ±24 mA drive | Designed for 3.3 V systems only - cannot operate at 5 V; unsuitable for TTL input compatibility or 5 V bus isolation | Select when interfacing exclusively with 3.3 V logic and lower power is critical; avoid for 5 V or mixed-voltage use. |
| 74ACT245SCX | Same 4.5–5.5 V range; higher drive (±24 mA), faster tPD (3.5 ns); no guaranteed latch-up immunity spec | Lacks JESD17 latch-up rating >250 mA; HBM ESD only ±2 kV (same), but CDM rating unspecified | Prefer for speed-critical 5 V-only designs where latch-up risk is mitigated externally; verify board-level ESD protection. |
Compared with SN74AHCT245PW, SN74LVC245APW requires full 3.3 V system integration and lacks TTL input support, while 74ACT245SCX trades verified latch-up immunity for marginal speed gain - making SN74AHCT245PW the optimal choice for robust 5 V industrial bus isolation.
Availability
SN74AHCT245PW is available at Aetrix Electronics and suitable for microcontroller bus expansion, industrial I/O module interface, legacy system data translation, and test equipment signal routing requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SN74AHCT245PW 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 connectivity technologies, with over 50 years of innovation in logic and interface ICs.
The SNx4AHCT245 family was engineered for reliable 5 V bus bridging in industrial control, instrumentation, and legacy system upgrades - emphasizing robustness, TTL compatibility, and predictable 3-state behavior over raw speed.
FAQ
What is the recommended power-up sequence for SN74AHCT245PW?
Apply VCC before asserting any inputs. Tie OE to VCC through a 10 kΩ pullup resistor to ensure all I/Os remain in high-impedance state until firmware configures DIR and deasserts OE. This prevents bus contention during reset. The SN74AHCT245PW has no internal power-on reset, so external biasing is mandatory for deterministic startup behavior.
Can SN74AHCT245PW interface directly with 3.3 V microcontrollers?
Yes - the SN74AHCT245PW accepts 3.3 V logic levels as valid inputs (VIH = 2 V min, VIL = 0.8 V max), making it suitable for 3.3 V → 5 V up-translation. However, its outputs swing rail-to-rail at 5 V, so downstream 3.3 V receivers require level-shifting or tolerance to 5 V inputs unless explicitly 5 V-tolerant.
Does SN74AHCT245PW support hot insertion or live bus swapping?
No - the SN74AHCT245PW lacks bus-hold or Ioff partial-power-down protection. Applying signals to A/B pins while VCC = 0 V may cause backpowering or latch-up. For hot-swap applications, use devices with Ioff specification (e.g., SN74AVCH series) or add external isolation circuitry.
What is the maximum capacitive load SN74AHCT245PW can drive reliably?
The SN74AHCT245PW is characterized up to 50 pF load capacitance, with tPLH/tPHL increasing from 4.5 ns (15 pF) to 8.7 ns (50 pF). For stable operation beyond 50 pF, add series termination or reduce edge rate via external RC; exceeding ±25 mA per output risks parametric shift or reliability degradation.
How does the latch-up immunity of SN74AHCT245PW impact system design?
The SN74AHCT245PW exceeds 250 mA latch-up immunity per JESD17, allowing it to withstand transient overcurrent events (e.g., accidental shorts, ESD-induced current spikes) without destructive failure. This eliminates need for external current-limiting resistors in most industrial bus interfaces, simplifying layout and improving signal integrity.
SN74AHCT245PW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- 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:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP
SN74AHCT245PW FAQ
1.How can I place an order for SN74AHCT245PW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT245PW 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 SN74AHCT245PW reliable?
The price and inventory of SN74AHCT245PW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT245PW is usually 5 days.
3.What payment methods are accepted for SN74AHCT245PW?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT245PW transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHCT245PW?
SN74AHCT245PW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT245PW 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 SN74AHCT245PW?
For technical support, including SN74AHCT245PW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT245PW requirements.
6.How does Aetrix verify that SN74AHCT245PW is sourced from the original manufacturer or authorized distributors?
All SN74AHCT245PW 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 SN74AHCT245PW meets industry standards.
7.What is the process for return or replacement of SN74AHCT245PW?
All SN74AHCT245PW units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT245PW, 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 SN74AHCT245PW part is unused and in its original packaging.
Return procedure for SN74AHCT245PW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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