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onsemi 74ACTQ245SCX
- Part No.:
- 74ACTQ245SCX
- Manufacturer:
- onsemi
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
74ACTQ245SCX.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,667
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Product details
Overview
74ACTQ245SCX from Fairchild Semiconductor is an octal bidirectional transceiver with 3-STATE inputs/outputs, designed for bus-oriented data transfer between two 8-bit buses. It operates at 4.5V–5.5V supply, delivers ±24 mA drive strength per I/O, and features Quiet Series technology to suppress simultaneous switching noise. Used in legacy industrial control backplanes and memory address/data bus isolation.
For engineers reviewing the 74ACTQ245SCX datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed 5.0V AC performance, dynamic input thresholds (VIHD/VILD), quiet output voltage swing (VOLP/VOLV), and SOIC-20 package compatibility with JEDEC MS-013 footprint.
Technical Context
The 74ACTQ245SCX implements a non-inverting bidirectional buffer architecture controlled by separate Transmit/Receive (T/R) and Output Enable (OE) inputs. Direction is determined solely by T/R logic level: active-HIGH enables A→B flow; active-LOW enables B→A flow. OE HIGH forces both ports into high-impedance state regardless of T/R state.
It uses Fairchild's FACT Quiet Series technology, incorporating GTO output control and undershoot correction plus split ground bus layout. This ensures guaranteed simultaneous switching noise suppression and dynamic threshold performance-specifically VIHD ≥ 2.2 V and VILD ≤ 0.8 V at VCC = 5.0 V-with measured VOLP ≤ 1.5 V and VOLV ≥ 0.6 V under worst-case switching conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - Valid only within this narrow TTL-compatible range; operation outside invalidates all AC/DC specs. |
| tPHL / tPLH | 1.5 ns (typ), 7.5 ns (max) - Propagation delay from data input to output, critical for synchronous bus timing budgets. |
| IOL / IOH | 24 mA sink/source - Sustained drive capability enabling direct connection to 50-pF bus loads without external buffers. |
| VOLP / VOLV | 1.1 V (typ), 1.5 V (max) / 0.6 V (min) - Dynamic low-level output voltage bounds defining noise margin during simultaneous switching. |
| VIHD / VILD | 2.2 V (min) / 0.8 V (max) - Dynamic input thresholds ensuring reliable recognition of logic levels amid transient noise. |
| tPZL / tPHZ | 2.0 ns (typ), 9.5 ns (max) / 1.0 ns (typ), 10.5 ns (max) - Enable/disable timing affecting bus contention avoidance windows. |
| CIN / CI/O | 4.5 pF / 15 pF - Input and I/O capacitance values directly impacting signal integrity and fan-out limits on high-speed traces. |
Pinout & Package
74ACTQ245SCX is packaged in a 20-lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013 compliant, 0.300" wide body with standard gull-wing leads. Pin pitch is 25.4 mil (0.65 mm), total package width 7.5 mm, length 12.8 mm, height 2.35 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OE) | Output Enable Input | Active-HIGH global disable: forces all A/B pins into high-Z regardless of T/R state; essential for bus arbitration. |
| 2–9 (A0–A7) | Side A Bidirectional I/O | 8-bit port configurable as input or output based on T/R; shares same physical pins for both directions. |
| 10 (GND) | Ground Reference | Primary return path for all internal logic and I/O current; split ground bus design reduces ground bounce. |
| 11–18 (B0–B7) | Side B Bidirectional I/O | 8-bit port mirroring A-side behavior; direction relative to A-side determined by T/R pin logic level. |
| 19 (T/R) | Transmit/Receive Control | Direction selector: HIGH = A→B data flow; LOW = B→A data flow; asynchronous to OE and data edges. |
| 20 (VCC) | Power Supply | +5 V nominal supply; must be regulated within 4.5–5.5 V; decoupling required near pin 20 due to high di/dt during switching. |
Key Features
| Feature | Design Value |
|---|---|
| Quiet Series Noise Suppression | Guaranteed VOLP ≤ 1.5 V and VOLV ≥ 0.6 V at 5.0 V, enabling stable operation in high-noise backplane environments. |
| GTO Output Control | Gate Turn-Off circuitry actively manages edge rates to reduce EMI and overshoot during 0→1 and 1→0 transitions. |
| Split Ground Bus Layout | Dedicated ground routing separates logic and I/O return paths, minimizing ground bounce-induced timing skew across all 16 I/Os. |
| Dynamic Threshold Guarantee | VIHD ≥ 2.2 V and VILD ≤ 0.8 V at VCC = 5.0 V ensure robust noise immunity even during simultaneous multi-bit switching. |
| Pin-to-Pin Skew Control | tOSHL/tOSLH ≤ 1.0 ns (max) guarantees deterministic timing alignment across all eight channels for synchronous bus applications. |
Applications
| Industrial Backplane Data Transfer | Legacy Memory Address Bus Isolation |
|---|---|
Use Scenario: Isolating CPU address/data buses from peripheral expansion slots in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: Bidirectional bus transceiver enabling read/write cycles between master and slave modules while preventing bus contention. Use Value: ±24 mA drive supports long trace runs on 50-pF backplanes; Quiet Series ensures no corruption of adjacent analog or timing signals. | Use Scenario: Separating RAM/ROM address latches from microcontroller address bus in embedded instrumentation systems. IC Role / Device Role / Timing Role: Direction-controlled buffer that isolates memory address lines during DMA transfers to avoid address glitches. Use Value: Guaranteed tPHZ ≤ 10.5 ns allows safe deassertion before next cycle; high-Z state eliminates loading on shared address lines. |
| Microcontroller Peripheral Interface | Test Equipment Digital I/O Expansion |
Use Scenario: Extending GPIO count of 8-bit microcontrollers (e.g., 8051 derivatives) to drive external displays or sensors. IC Role / Device Role / Timing Role: Level-shifting and bus-driving interface between MCU I/O and higher-capacity peripherals. Use Value: 5.0 V compatible VIH/VIL thresholds match TTL logic families; 24 mA sink enables direct LED driving without series resistors. | Use Scenario: Adding isolated digital I/O channels to automated test equipment (ATE) mainframes via modular daughterboards. IC Role / Device Role / Timing Role: Reconfigurable bidirectional data path between controller FPGA and DUT interface connectors. Use Value: SOIC-20 package fits dense PCB layouts; guaranteed skew <1 ns ensures deterministic sampling of parallel test vectors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 74ACT245SCX | No Quiet Series features; higher simultaneous switching noise (VOLP up to 2.2 V); no GTO or split ground bus. | Lacks guaranteed dynamic threshold performance (VIHD/VILD not specified); unsuitable where noise margin is critical. | Select when cost is primary and board-level noise filtering is already implemented. |
| SN74LVC245APWR | 3.3 V only (1.65–3.6 V); lower drive (24 mA max but derated above 3.3 V); different pinout (T/R and OE swapped). | Not pin-compatible; requires PCB redesign; intended for modern low-voltage systems, not 5 V legacy buses. | Choose only for new 3.3 V designs requiring LVC speed/power trade-off; not a drop-in replacement. |
Compared with 74ACTQ245SCX, the 74ACT245SCX offers identical pinout and basic function but lacks noise-suppression hardware, while SN74LVC245APWR provides lower voltage operation at the cost of incompatible supply and layout requirements.
Availability
74ACTQ245SCX is available at Aetrix Electronics and suitable for industrial backplane data transfer, legacy memory address bus isolation, and microcontroller peripheral interface applications requiring stable component supply and long-term obsolescence management.
Supply support for 74ACTQ245SCX 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
Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and logic ICs before its acquisition by ON Semiconductor in 2016. Its legacy logic portfolio remains widely deployed in industrial and automotive systems.
The 74ACTQ245SCX belongs to the ACTQ Quiet Series family, engineered specifically for noise-sensitive 5 V bus applications where simultaneous switching noise and dynamic threshold stability are critical system requirements.
FAQ
What is the operating voltage range for the 74ACTQ245SCX?
The 74ACTQ245SCX operates strictly within 4.5 V to 5.5 V. Unlike broader-range ACQ variants, it is not rated for 3.3 V or 2.0 V operation. Exceeding this range violates Absolute Maximum Ratings and invalidates all guaranteed AC/DC specifications including propagation delay, drive strength, and noise margins.
Does the 74ACTQ245SCX support true bidirectional data flow without external logic?
Yes, the 74ACTQ245SCX supports true bidirectional data flow using only its dedicated T/R (pin 19) and OE (pin 1) inputs. When OE is LOW, T/R determines direction: HIGH enables A→B transfer; LOW enables B→A transfer. No external gates or direction-control logic are needed, simplifying bus arbitration design.
How does the Quiet Series technology in the 74ACTQ245SCX reduce noise?
The 74ACTQ245SCX integrates Fairchild's Quiet Series technology-including GTO output control, undershoot correction circuitry, and a split ground bus-to limit dynamic output voltage excursions. Measured VOLP ≤ 1.5 V and VOLV ≥ 0.6 V at 5.0 V confirm suppressed ground bounce and crosstalk during simultaneous multi-bit switching events.
Is the 74ACTQ245SCX pin-compatible with standard 74ACT245 devices?
Yes, the 74ACTQ245SCX is pin-compatible with the 74ACT245SCX in SOIC-20 (M20B) packaging, sharing identical pinout, footprint, and DC logic behavior. However, it adds Quiet Series circuitry internally-no external changes are needed, but noise-sensitive applications benefit from the enhanced dynamic performance without layout modification.
What are the thermal limitations of the 74ACTQ245SCX in continuous operation?
The 74ACTQ245SCX has a maximum junction temperature (TJ) of 140°C for PDIP packages and is rated for ambient operation from –40°C to +85°C. Power dissipation depends on switching frequency and load; typical ICC is 4.0 µA (quiescent), rising with activity. Thermal design must ensure θJA remains within SOIC-20 limits-derating required above 70°C ambient for sustained 24 mA per pin operation.
74ACTQ245SCX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74ACTQ
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 24mA, 24mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SOIC
74ACTQ245SCX FAQ
1.How can I place an order for 74ACTQ245SCX through Aetrix?
Please submit a Request for Quotation (RFQ) for 74ACTQ245SCX 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 74ACTQ245SCX reliable?
The price and inventory of 74ACTQ245SCX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74ACTQ245SCX is usually 5 days.
3.What payment methods are accepted for 74ACTQ245SCX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74ACTQ245SCX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74ACTQ245SCX?
74ACTQ245SCX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74ACTQ245SCX 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 74ACTQ245SCX?
For technical support, including 74ACTQ245SCX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74ACTQ245SCX requirements.
6.How does Aetrix verify that 74ACTQ245SCX is sourced from the original manufacturer or authorized distributors?
All 74ACTQ245SCX 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 74ACTQ245SCX meets industry standards.
7.What is the process for return or replacement of 74ACTQ245SCX?
All 74ACTQ245SCX units undergo pre-shipment inspection (PSI). If there is an issue with 74ACTQ245SCX, 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 74ACTQ245SCX part is unused and in its original packaging.
Return procedure for 74ACTQ245SCX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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