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onsemi 74ACT245MTC
- Part No.:
- 74ACT245MTC
- Manufacturer:
- onsemi
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
74ACT245MTC.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:295
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Product details
Overview
74ACT245MTC from Fairchild Semiconductor (manufactured by Rochester Electronics) is an octal bidirectional transceiver with 3-STATE inputs/outputs, designed for bus-oriented data transfer between two 8-bit parallel buses. It features TTL-compatible inputs, ±24mA output drive capability at both A and B ports, active-HIGH Transmit/Receive control, and HIGH-Z output disable via OE. Used in legacy industrial backplane interfaces and memory-mapped I/O expansion.
For engineers reviewing the 74ACT245MTC datasheet, pinout, applications, or equivalent options, key selection criteria include its 4.5V–5.5V supply range, 7.5ns typical propagation delay (VCC = 5.0V), 3-STATE bidirectional flow control, and TSSOP-20 package compatibility with high-density PCB layouts.
Technical Context
The 74ACT245MTC implements eight non-inverting bidirectional buffers with independent direction control via the T/R input and global 3-STATE enable via OE. Its TTL-compatible inputs accept standard 5V logic thresholds (VIH = 2.0V min, VIL = 0.8V max), enabling direct interfacing with legacy microcontrollers and peripheral ICs.
Each A and B port supports ±24mA DC output current under guaranteed conditions, with VOL ≤ 0.44V at IOL = 24mA and VOH ≥ 3.76V at IOH = −24mA (VCC = 4.5V–5.5V). Propagation delays are symmetric (tPLH/tPHL ≤ 8.0ns) and output enable/disable times are tightly specified (tPZH/tPLZ ≤ 12.0ns).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5V to 5.5V - ensures compatibility with standard 5V TTL/CMOS systems without level-shifting. |
| Output Drive | ±24mA per pin - supports driving multiple loads or longer traces on shared buses. |
| Propagation Delay | ≤8.0ns (VCC = 5.0V, CL = 50pF) - enables reliable operation in 125MHz bus cycles with margin. |
| Input Compatibility | TTL-compatible (VIH ≥ 2.0V, VIL ≤ 0.8V) - interoperable with 74LS, 74F, and microcontroller GPIOs. |
| Operating Temperature | −40°C to +85°C - qualified for industrial ambient environments without derating. |
| I/O Leakage | ±3.0µA max (IOZT) - minimizes standby current in powered-down bus segments. |
| Package | TSSOP-20 (JEDEC MO-153, 4.4mm wide) - surface-mount footprint with 0.65mm pitch for compact layout. |
Pinout & Package
74ACT245MTC uses a 20-lead Thin Shrink Small Outline Package (TSSOP), JEDEC MO-153 compliant, with 0.65mm lead pitch and 4.4mm body width. The package is RoHS-compliant and lead-free per J-STD-020B.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (OE) | Output Enable Input | Active-HIGH global disable: drives all A/B pins to HIGH-Z when asserted. |
| 2–9 (A0–A7) | Side A I/O Terminals | Bidirectional data lines; direction determined by T/R; 3-STATE when OE = HIGH. |
| 10 (GND) | Ground Reference | Primary return path for all internal logic and I/O currents. |
| 11–18 (B0–B7) | Side B I/O Terminals | Bidirectional data lines mirroring A-side behavior; same 3-STATE and direction control. |
| 19 (T/R) | Transmit/Receive Control | Active-HIGH = A→B data flow; Active-LOW = B→A data flow. |
| 20 (VCC) | Power Supply | +4.5V to +5.5V supply for core logic and output drivers. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional bus interface | Single device replaces two unidirectional transceivers, reducing component count and routing complexity on 8-bit data paths. |
| TTL-compatible inputs | Eliminates need for external level shifters when connecting to 74LS, 74F, or older microprocessor buses. |
| 24mA output sink/source | Drives standard TTL loads (up to 10 LSTTL units) directly without external buffers. |
| Low ICC quiescent current | ≤40µA max (VCC = 5.5V) - reduces system power budget in always-on control modules. |
| Fast 3-STATE switching | tPZH/tPLZ ≤ 12.0ns ensures minimal bus contention during direction or enable transitions. |
Applications
| Industrial Backplane Interface | Legacy Microcontroller I/O Expansion |
|---|---|
Use Scenario: Isolating and extending 8-bit address/data buses between CPU and peripheral cards in DIN-rail mounted PLC chassis. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing data flow direction and enabling/disabling bus segments under CPU control. Use Value: Enables hot-swap-capable modular architecture with deterministic 8ns timing margins and 24mA drive for long backplane traces. |
Use Scenario: Adding parallel I/O capability to an 8051-based motor controller where native port pins are insufficient. IC Role / Device Role / Timing Role: Expanding GPIO count while preserving bidirectional communication with sensors and actuators over shared data lines. Use Value: TTL-compatible inputs simplify connection to 8051's native 5V outputs; 24mA drive supports direct LED indicators and relay drivers. |
| Memory-Mapped Peripheral Bridge | Test Equipment Bus Arbitration |
Use Scenario: Interfacing an FPGA-based logic analyzer core to external SRAM and register banks using a common 8-bit data bus. IC Role / Device Role / Timing Role: Direction-controlled data conduit synchronizing read/write transfers between FPGA and memory peripherals. Use Value: Sub-8ns propagation delay meets SRAM access timing; 3-STATE isolation prevents bus conflicts during FPGA reconfiguration. |
Use Scenario: Managing shared GPIB or IEEE-488 bus lines among multiple test instruments in automated calibration racks. IC Role / Device Role / Timing Role: Enabling/disabling instrument-specific bus drivers and controlling data direction during handshaking sequences. Use Value: OE and T/R pins allow precise software-controlled bus arbitration without external logic; LOW leakage preserves signal integrity during idle periods. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT245DBR | TSSOP-20 package, identical AC/ACT logic family, same 4.5–5.5V VCC and ±24mA drive specs. | TI-manufactured; identical pinout and timing but different qualification pedigree (industrial vs. military-grade Rochester). | Select SN74ACT245DBR for TI-design ecosystems requiring TI-qualified documentation and support infrastructure. |
| 74LCX245MTCX | Lower VCC range (2.0–3.6V), 24mA drive, but CMOS input thresholds (VIH = 70% VCC); not TTL-compatible. | Designed for mixed-voltage 3.3V systems; requires level translation when interfacing with 5V TTL sources. | Choose 74LCX245MTCX only when migrating to 3.3V logic domains and full TTL compatibility is unnecessary. |
Compared with 74ACT245MTC, SN74ACT245DBR offers identical electrical behavior and drop-in replacement capability in commercial designs, whereas 74LCX245MTCX trades TTL compatibility for lower voltage operation-making it unsuitable for legacy 5V bus environments without additional interface circuitry.
Availability
74ACT245MTC is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy microcontroller I/O expansion, memory-mapped peripheral bridging, and test equipment bus arbitration requiring stable component supply across extended product lifecycles.
Supply support for 74ACT245MTC 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 (now part of ON Semiconductor) pioneered high-performance logic families including ACT, delivering robust 5V TTL-compatible CMOS devices for industrial and computing applications.
Rochester Electronics manufactures 74ACT245MTC under license using original Fairchild die or recreated wafers, targeting long-lifecycle support for legacy 5V bus architectures in defense, aerospace, and industrial control systems.
FAQ
What is the recommended operating voltage range for the 74ACT245MTC?
The 74ACT245MTC is specified for a supply voltage range of 4.5V to 5.5V. Operation outside this range may result in undefined logic states or degraded output drive strength. This range ensures full compliance with TTL input thresholds and guarantees ±24mA output capability at both A and B ports under worst-case temperature and voltage conditions.
Does the 74ACT245MTC support true bidirectional data flow without external logic?
Yes, the 74ACT245MTC supports true bidirectional data flow using its dedicated T/R (Transmit/Receive) input. When T/R is HIGH, data flows from A ports to B ports; when LOW, data flows from B ports to A ports-all without requiring external direction-control logic or additional transceivers.
What is the maximum propagation delay of the 74ACT245MTC at 5.0V supply?
At VCC = 5.0V and CL = 50pF, the maximum propagation delay (tPLH or tPHL) for the 74ACT245MTC is 8.0ns over the full operating temperature range (−40°C to +85°C). This value is guaranteed in the datasheet and applies to both A→B and B→A signal paths.
Can the 74ACT245MTC be used in place of a 74LS245 in existing designs?
Yes, the 74ACT245MTC is a functional and pin-compatible upgrade to the 74LS245. Its TTL-compatible inputs (VIH ≥ 2.0V, VIL ≤ 0.8V), identical pinout, and higher output drive (±24mA vs. ±8mA for LS) allow direct substitution-improving noise immunity and load-driving capability without board changes.
Is the 74ACT245MTC RoHS-compliant and lead-free?
Yes, the 74ACT245MTC is manufactured as lead-free per JEDEC J-STD-020B and complies with RoHS Directive 2011/65/EU. The TSSOP-20 package uses matte tin lead finish and meets industry-standard reflow profile requirements for Pb-free assembly.
74ACT245MTC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74ACT
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- 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-TSSOP
74ACT245MTC FAQ
1.How can I place an order for 74ACT245MTC through Aetrix?
Please submit a Request for Quotation (RFQ) for 74ACT245MTC 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 74ACT245MTC reliable?
The price and inventory of 74ACT245MTC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74ACT245MTC is usually 5 days.
3.What payment methods are accepted for 74ACT245MTC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74ACT245MTC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74ACT245MTC?
74ACT245MTC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74ACT245MTC 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 74ACT245MTC?
For technical support, including 74ACT245MTC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74ACT245MTC requirements.
6.How does Aetrix verify that 74ACT245MTC is sourced from the original manufacturer or authorized distributors?
All 74ACT245MTC 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 74ACT245MTC meets industry standards.
7.What is the process for return or replacement of 74ACT245MTC?
All 74ACT245MTC units undergo pre-shipment inspection (PSI). If there is an issue with 74ACT245MTC, 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 74ACT245MTC part is unused and in its original packaging.
Return procedure for 74ACT245MTC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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