My Inquiry
My Account
onsemi 74ACTQ245MSAX
- Part No.:
- 74ACTQ245MSAX
- Manufacturer:
- onsemi
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
74ACTQ245MSAX.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,111
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
74ACTQ245MSAX 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 for controlled dynamic noise. Used in backplane interface, memory address buffering, and legacy system bus isolation.
For engineers reviewing the 74ACTQ245MSAX datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed 5.0V AC performance, simultaneous switching noise suppression (VOLP ≤1.5 V), output disable time ≤10.5 ns, and compatibility with JEDEC MO-150 SSOP-20 footprint.
Technical Context
The 74ACTQ245MSAX implements a non-inverting bidirectional buffer architecture controlled by separate Transmit/Receive (T/R) and Output Enable (OE) inputs. Direction control is level-sensitive: T/R = HIGH enables A→B flow; T/R = LOW enables B→A flow. OE = HIGH forces both ports into high-impedance state regardless of T/R state.
It employs Fairchild's FACT Quiet Series technology, integrating GTO output control and undershoot correction with split ground bus routing to reduce simultaneous switching noise. Dynamic input thresholds (VIHD = 2.2 V, VILD = 0.8 V at VCC = 5.0 V) and quiet output voltage limits (VOLP = 1.5 V, VOLV = 0.6 V) are specified under defined 1 MHz switching conditions with 50 pF load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures compatibility with standard 5 V TTL/CMOS systems and stable operation across industrial voltage tolerance. |
| Drive Strength | ±24 mA per I/O - Sufficient to directly drive terminated bus lines or memory address registers without external buffers. |
| Propagation Delay | tPLH/tPHL ≤ 7.5 ns @ CL = 50 pF - Enables reliable timing in high-speed 8-bit parallel interfaces up to ~100 MHz effective data rate. |
| Output Disable Time | tPLZ/tPHZ ≤ 10.5 ns @ VCC = 5.0 V - Supports fast bus turnaround in bidirectional protocols requiring rapid direction reversal. |
| Quiet Output Noise | VOLP ≤ 1.5 V, VOLV ≥ 0.6 V @ VCC = 5.0 V - Quantified dynamic low-level noise margin enabling robust signal integrity in dense PCB layouts. |
| Input Thresholds | VIH = 2.0 V, VIL = 0.8 V - Matches TTL-compatible logic levels, ensuring interoperability with legacy 5 V microcontrollers and peripherals. |
| Operating Temperature | –40 °C to +85 °C - Qualified for industrial ambient environments without derating. |
Pinout & Package
74ACTQ245MSAX is housed in a 20-lead Shrink Small Outline Package (SSOP), JEDEC MO-150 compliant, 5.3 mm wide, with 0.65 mm lead pitch. The package provides compact board area and improved thermal performance over SOIC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OE) | Output Enable Input | Active-HIGH global disable: forces all A and B pins into high-Z regardless of T/R state - essential for bus arbitration. |
| 2–9 (A0–A7) | Side A Bidirectional I/O | 3-STATE inputs/outputs tied to local bus segment; direction determined by T/R and OE - supports memory-mapped peripheral interfacing. |
| 10 (GND) | Ground Reference | Primary return path for all I/O and internal logic; split ground bus design reduces ground bounce during simultaneous switching. |
| 11–18 (B0–B7) | Side B Bidirectional I/O | 3-STATE inputs/outputs tied to remote bus segment; complements A-side for full-duplex data exchange - used in ISA/PCI bridge isolation. |
| 19 (T/R) | Transmit/Receive Control | Level-sensitive direction selector: HIGH = A→B, LOW = B→A - eliminates need for external direction logic in synchronous bus transfers. |
| 20 (VCC) | Power Supply | +5 V nominal supply; decoupling required near pin 20 due to high di/dt during switching - recommended 100 nF ceramic capacitor. |
Key Features
| Feature | Design Value |
|---|---|
| Quiet Series Noise Suppression | Guaranteed VOLP ≤1.5 V and VOLV ≥0.6 V under simultaneous switching - prevents false triggering in adjacent sensitive analog or clock circuits. |
| GTO Output Control | Controlled slew-rate outputs reduce EMI and crosstalk in high-density routing - eliminates need for external series termination resistors in many cases. |
| Split Ground Bus Architecture | Dedicated ground routing minimizes shared-impedance coupling between switching outputs - improves dynamic threshold stability across all eight channels. |
| Guaranteed Pin-to-Pin Skew | tOSHL/tOSLH ≤1.0 ns - ensures deterministic timing alignment across all eight data paths, critical for byte-wide synchronous transfers. |
| Enhanced Latch-Up Immunity | Rated to withstand >300 mA transient current - protects against inadvertent power-rail coupling or hot-swap transients in modular backplane systems. |
Applications
| Industrial Backplane Interface | Legacy Memory Address Buffering |
|---|---|
Use Scenario: Isolating CPU address/data bus from expansion slot peripherals in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing 8-bit address latch signals between main controller and field I/O modules. Use Value: ±24 mA drive and <10.5 ns disable time enable clean bus turnaround during multi-cycle read/write sequences without added glue logic. | Use Scenario: Driving 8-bit address lines to multiple SRAM chips on a single PCB with shared address decode. IC Role / Device Role / Timing Role: Unidirectional or bidirectional address register buffer with 3-STATE control synchronized to chip select timing. Use Value: Guaranteed VIH/VIL thresholds ensure reliable decoding across temperature, while quiet output behavior prevents address corruption during burst accesses. |
| ISA Bus Signal Isolation | Microcontroller Peripheral Expansion |
Use Scenario: Interfacing modern FPGA-based ISA master to legacy ISA slave cards requiring strict 5 V TTL signaling compliance. IC Role / Device Role / Timing Role: Level-shifting and noise-isolated bidirectional data path between ISA data bus and FPGA I/O bank. Use Value: ACTQ family 5 V operation and 7.5 ns propagation delay meet ISA timing budgets; Quiet Series suppresses noise that could disrupt ISA interrupt signaling. | Use Scenario: Expanding GPIO count of an 8-bit microcontroller via parallel port using external peripheral ICs. IC Role / Device Role / Timing Role: Bidirectional data shuttle between MCU port and peripheral register banks (e.g., display drivers, ADCs). Use Value: T/R-controlled direction and OE-gated high-Z allow software-configurable read/write cycles without hardware direction control lines. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 74ACT245MTCX | No Quiet Series features; higher simultaneous switching noise (VOLP not specified); no GTO or split ground bus. | Lacks guaranteed dynamic noise margins; requires additional layout mitigation (guard traces, extra decoupling) in noise-sensitive systems. | Select when cost sensitivity outweighs noise control requirements and board space allows added filtering. |
| SN74LVC245APWR | 3.3 V only (1.65–3.6 V); lower drive (±24 mA typical but not guaranteed over temp); different pinout (T/R and OE swapped). | Not pin-compatible; requires level translation for 5 V systems; unsuitable for direct 5 V bus replacement. | Choose only for new 3.3 V designs where voltage scaling and lower power are primary goals. |
Compared with 74ACT245MTCX and SN74LVC245APWR, the 74ACTQ245MSAX uniquely delivers factory-guaranteed quiet switching behavior and 5 V bus compatibility in a compact SSOP-20 package - making it the only option among the three qualified for legacy industrial backplane noise budgets without redesign.
Availability
74ACTQ245MSAX is available at Aetrix Electronics and suitable for industrial backplane interface, legacy memory address buffering, and ISA bus signal isolation requiring stable component supply and long-term lifecycle support.
Supply support for 74ACTQ245MSAX 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 analog and mixed-signal ICs, acquired by ON Semiconductor in 2016. Its legacy products remain widely deployed in industrial and automotive systems.
The 74ACTQ245MSAX belongs to the FACT Quiet Series transceiver family, engineered specifically for noise-critical 5 V bus applications where simultaneous switching noise must be bounded and timing predictability is essential.
FAQ
What is the operating voltage range for the 74ACTQ245MSAX?
The 74ACTQ245MSAX operates strictly within 4.5 V to 5.5 V. This range ensures compatibility with standard 5 V TTL logic families and guarantees all AC/DC specifications-including propagation delay, drive strength, and quiet output behavior-are met. Operation outside this window is not characterized and may result in undefined functionality or reliability degradation.
Does the 74ACTQ245MSAX support true bidirectional data flow without external logic?
Yes, the 74ACTQ245MSAX supports true bidirectional data flow using only its dedicated T/R and OE inputs. When OE is LOW, T/R = HIGH enables A→B transfer; T/R = LOW enables B→A transfer. No external direction-control logic or discrete gates are needed-this is intrinsic to the device's architecture and confirmed in the truth table of the official datasheet.
What does "Quiet Series" mean for the 74ACTQ245MSAX in practical design terms?
"Quiet Series" for the 74ACTQ245MSAX means factory-guaranteed limits on simultaneous switching noise: VOLP ≤1.5 V and VOLV ≥0.6 V under defined test conditions. Practically, this allows placement near noise-sensitive circuits (e.g., ADC references or crystal oscillators) without added shielding or guard traces-reducing layout complexity and validation risk in industrial backplanes.
Is the 74ACTQ245MSAX pin-compatible with standard 74ACT245 packages?
The 74ACTQ245MSAX shares identical pinout and electrical interface with non-Quiet 74ACT245 variants in the same SSOP-20 (MSA20) package, including 74ACT245MTCX. However, functional differences-especially in dynamic noise behavior and guaranteed skew-mean it is not a drop-in replacement where noise margins are critical, even though PCB layout remains unchanged.
What thermal considerations apply to the 74ACTQ245MSAX in continuous operation?
The 74ACTQ245MSAX is rated for junction temperatures up to 140 °C in PDIP packages, but the MSA20 SSOP variant has no published TJ(max) limit beyond the standard industrial range (–40 °C to +85 °C ambient). For continuous operation at full ±24 mA per pin, maintain θJA < 120 °C/W via adequate copper pour and airflow-derate ICC above 70 °C ambient per datasheet ICC vs. TA curves.
74ACTQ245MSAX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74ACTQ
- Package/Case:
- 20-SSOP (0.209", 5.30mm 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-SSOP
74ACTQ245MSAX FAQ
1.How can I place an order for 74ACTQ245MSAX through Aetrix?
Please submit a Request for Quotation (RFQ) for 74ACTQ245MSAX 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 74ACTQ245MSAX reliable?
The price and inventory of 74ACTQ245MSAX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74ACTQ245MSAX is usually 5 days.
3.What payment methods are accepted for 74ACTQ245MSAX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74ACTQ245MSAX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74ACTQ245MSAX?
74ACTQ245MSAX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74ACTQ245MSAX 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 74ACTQ245MSAX?
For technical support, including 74ACTQ245MSAX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74ACTQ245MSAX requirements.
6.How does Aetrix verify that 74ACTQ245MSAX is sourced from the original manufacturer or authorized distributors?
All 74ACTQ245MSAX 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 74ACTQ245MSAX meets industry standards.
7.What is the process for return or replacement of 74ACTQ245MSAX?
All 74ACTQ245MSAX units undergo pre-shipment inspection (PSI). If there is an issue with 74ACTQ245MSAX, 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 74ACTQ245MSAX part is unused and in its original packaging.
Return procedure for 74ACTQ245MSAX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
74ACTQ245MSAX Tags
-
SN74LVC1G17DBVR
Texas Instruments
-
SN74LVC1G07DCKR
Texas Instruments
-
SN74LVC1G17DCKR
Texas Instruments
-
SN74LVC1G07DBVR
Texas Instruments
-
SN74LVC1G125DCKR
Texas Instruments
-
SN74AHCT1G126DBVR
Texas Instruments
-
SN74LVC1G125DBVR
Texas Instruments
-
SN74AHCT1G125DBVR
Texas Instruments
-
SN74LVC2G17DBVR
Texas Instruments
-
SN74LVC2G07DCKR
Texas Instruments
-
SN74LVC1G34DCKR
Texas Instruments
-
SN74LVC2G17DCKR
Texas Instruments
Tech Hub
Counterfeit components can hide behind convincing markings and passing basic function tests. This engineering reference covers source traceability, external inspection, X-ray, XRF, electrical testing, …
A practical engineering and sourcing framework covering lifecycle verification, lifetime-buy calculations, replacement qualification, supplier checks and counterfeit-risk controls.
TTL and CMOS logic families differ in thresholds, loading, output drive, power and timing. This engineering guide compares 74HC and 74HCT, calculates noise margins and checks 3.3 V/5 V compatibility.
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
