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onsemi MC74ACT245DTG
- Part No.:
- MC74ACT245DTG
- Manufacturer:
- onsemi
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
MC74ACT245DTG.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:260
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Product details
Overview
MC74ACT245DTG from onsemi is an octal bidirectional transceiver with 3-state inputs/outputs, designed for bus-oriented data transfer between two 8-bit parallel buses. It supports TTL-compatible inputs, delivers ±24 mA output drive at 5 V, and features independent transmit/receive (T/R) and output enable (OE) controls for flexible direction and bus isolation. Used in microcontroller peripheral interfacing and legacy bus bridging.
For engineers reviewing the MC74ACT245DTG datasheet, pinout, applications, or equivalent options, key selection criteria include 5 V supply compatibility, bidirectional 3-state bus control, propagation delay under 8 ns at 5 V, and TSSOP-20 packaging for space-constrained PCBs.
Technical Context
The MC74ACT245DTG implements eight non-inverting bidirectional buffers with separate T/R polarity control and active-high OE. Direction is determined solely by the T/R input: low enables B→A flow, high enables A→B flow. Both ports exhibit identical ±24 mA sink/source capability and TTL-compatible input thresholds (VIH = 2.0 V, VIL = 0.8 V at VCC = 5.5 V).
Its 3-state outputs achieve high-impedance disable via OE high, with leakage current ≤±0.6 µA and fast enable/disable timing (tPZH/tPHZ ≤11 ns at 5 V, CL = 50 pF). Input and I/O capacitance are specified at 4.5 pF and 15 pF respectively, supporting clean signal integrity in high-speed digital buses.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Supply Range | 4.5 V to 5.5 V - Ensures reliable operation in standard 5 V TTL/CMOS systems without level-shifting. |
| Output Drive | ±24 mA - Sustains robust logic levels driving multiple loads or longer traces on shared buses. |
| Propagation Delay | Max 8.0 ns (tPLH/tPHL @ 5 V) - Enables use in 100+ MHz bus cycles with timing margin. |
| Input Compatibility | TTL-level (VIH = 2.0 V, VIL = 0.8 V) - Directly interfaces with legacy 5 V microcontrollers and peripherals. |
| 3-State Leakage | ±0.6 µA max (IOZT) - Minimizes bus contention current when disabled, critical for multi-driver buses. |
| Package | TSSOP-20 (Case 948E) - 6.5 mm × 4.4 mm footprint with 0.65 mm pitch, suitable for compact industrial PCBs. |
Pinout & Package
TSSOP-20 package (Case 948E), 0.65 mm lead pitch, 6.5 mm × 4.4 mm body size, exposed pad optional per design; RoHS-compliant, Pb-free.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | VCC / GND | Power supply (Pin 20) and ground (Pin 10) - Decoupling capacitor placement near these pins is mandatory for noise immunity. |
| 2–9 | A0–A7 | Side A bidirectional I/O - Connects to primary bus (e.g., microcontroller data bus); direction controlled by T/R. |
| 11–18 | B0–B7 | Side B bidirectional I/O - Connects to secondary bus (e.g., peripheral or memory bus); mirrors A-side behavior. |
| 19 | OE | Active-HIGH output enable - Drives all A/B pins to high-Z when HIGH; must be LOW for data transfer. |
| 20 | T/R | Transmit/Receive control - HIGH enables A→B flow; LOW enables B→A flow; no internal pull-up/down. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional bus control | Single T/R pin selects real-time data direction without external logic or clocking. |
| TTL-compatible inputs | Accepts standard 5 V TTL voltage thresholds, eliminating need for input level shifters in mixed-logic systems. |
| High-output drive | ±24 mA per pin sustains valid logic levels across 50 Ω transmission lines or fan-out of 10+ LS-TTL loads. |
| Low propagation skew | Matched tPLH/tPHL ensures simultaneous edge alignment across all 8 channels, preventing bus skew errors. |
| Pb-free TSSOP packaging | RoHS-compliant 20-pin thin shrink small outline package enables automated assembly and thermal reliability up to 150°C TJ. |
Applications
| Microcontroller Peripheral Interface | Legacy Bus Bridging |
|---|---|
Use Scenario: Interfacing an 8-bit microcontroller (e.g., 8051 derivative) with external parallel EEPROM or LCD controller. IC Role / Device Role / Timing Role: Bidirectional data buffer isolating MCU data bus from peripheral bus, with direction controlled by MCU GPIO. Use Value: Eliminates need for discrete direction-control logic; ±24 mA drive ensures reliable write pulses to EEPROM address latches. | Use Scenario: Connecting ISA-bus peripherals to modern FPGA-based host controllers in industrial test equipment. IC Role / Device Role / Timing Role: Level-translation and bus arbitration layer enabling legacy 5 V ISA signals to coexist with FPGA I/O banks. Use Value: 8 ns max propagation delay preserves ISA timing budgets; 3-state control allows dynamic bus sharing among multiple masters. |
| Memory Expansion Interface | Digital Signal Processor (DSP) Data Bus |
Use Scenario: Expanding external RAM capacity on a microcontroller board using dual-port SRAM or static RAM chips. IC Role / Device Role / Timing Role: Isolating address/data multiplexed bus segments during read/write cycles via OE and T/R coordination. Use Value: High-Z disable prevents bus contention during memory refresh; ±24 mA sink capability drives SRAM address strobes reliably. | Use Scenario: Supporting parallel data exchange between a fixed-point DSP (e.g., TMS320C54x) and ADC/DAC peripherals. IC Role / Device Role / Timing Role: Synchronizing bidirectional data transfers between DSP data bus and external converters using T/R as frame sync signal. Use Value: Matched channel delays ensure deterministic setup/hold timing across all 8 bits, critical for 16-bit audio sample integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bidirectional bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT245PW | Same logic function, identical AC/DC specs, but in TSSOP-20 package from Texas Instruments. | No functional difference; pinout matches MC74ACT245DTG exactly per TI datasheet SLAS082K. | Select if TI supply chain preference or dual-sourcing required; same layout and firmware support. |
| 74LVX245M | Lower VCC range (2.7–3.6 V), CMOS inputs only (VIH = 2.0 V min), ±24 mA drive retained. | Not suitable for 5 V systems; requires level translation when interfacing with TTL or 5 V microcontrollers. | Choose only for 3.3 V-only designs where lower power and reduced EMI are prioritized over 5 V compatibility. |
Compared with SN74ACT245PW and 74LVX245M, the MC74ACT245DTG uniquely combines 5 V TTL compatibility, ±24 mA drive, and TSSOP-20 packaging-making it optimal for retrofitting legacy 5 V bus architectures without redesigning power or interface logic.
Availability
MC74ACT245DTG is available at Aetrix Electronics and suitable for microcontroller peripheral interfacing, legacy bus bridging, and memory expansion applications requiring stable component supply and long-term industrial availability.
Supply support for MC74ACT245DTG 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
onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient innovation for automotive, industrial, cloud, medical, and IoT applications.
The MC74ACT245DTG belongs to onsemi's legacy logic family, engineered specifically for robust 5 V bus interfacing in industrial control, test equipment, and retrofitted embedded systems where reliability and pin compatibility are critical.
FAQ
What is the recommended operating voltage range for the MC74ACT245DTG?
The MC74ACT245DTG is specified for 4.5 V to 5.5 V operation. Operation outside this range risks undefined logic states or excessive ICC. The device draws <80 µA quiescent current at 5.5 V and maintains VIH/VIL thresholds compatible with standard TTL inputs across the full range. Always use local 0.1 µF ceramic decoupling at VCC pin 20.
How does the T/R pin control data direction in the MC74ACT245DTG?
In the MC74ACT245DTG, the T/R pin is an active-polarity control: when T/R is HIGH, data flows from A0–A7 to B0–B7; when T/R is LOW, data flows from B0–B7 to A0–A7. This occurs only when OE is LOW. No internal pull-up or pull-down exists, so the driving controller must actively assert T/R to avoid floating-state ambiguity.
Can the MC74ACT245DTG be used with 3.3 V logic systems?
The MC74ACT245DTG is not recommended for direct 3.3 V operation. Its minimum VCC is 4.5 V, and its TTL-compatible inputs require ≥2.0 V for VIH - marginal with 3.3 V logic highs. Using it at 3.3 V may cause excessive ICC, slow edges, or latch-up. For 3.3 V systems, consider the 74LVC245 or similar LV-family devices instead of the MC74ACT245DTG.
What is the maximum capacitive load the MC74ACT245DTG can drive reliably?
The MC74ACT245DTG AC specifications (propagation delay, enable/disable times) are characterized at CL = 50 pF. While it can drive higher loads, timing margins degrade linearly beyond that point. For loads >75 pF, derate tPLH/tPHL by ~0.1 ns/pF and verify setup/hold with oscilloscope measurements. The MC74ACT245DTG's 15 pF I/O capacitance helps minimize added loading on driven nets.
Is the MC74ACT245DTG pin-compatible with the MC74AC245DTG?
Yes - the MC74ACT245DTG and MC74AC245DTG share identical pinout, package (TSSOP-20), and DC/AC timing architecture. The sole functional difference is input threshold: MC74ACT245DTG has TTL-compatible inputs (VIH = 2.0 V), while MC74AC245DTG uses CMOS thresholds (VIH = 3.85 V at 5.5 V). Swapping them requires verifying source logic voltage levels to avoid misreads.
MC74ACT245DTG 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
MC74ACT245DTG FAQ
1.How can I place an order for MC74ACT245DTG through Aetrix?
Please submit a Request for Quotation (RFQ) for MC74ACT245DTG 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 MC74ACT245DTG reliable?
The price and inventory of MC74ACT245DTG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for MC74ACT245DTG is usually 5 days.
3.What payment methods are accepted for MC74ACT245DTG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for MC74ACT245DTG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for MC74ACT245DTG?
MC74ACT245DTG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your MC74ACT245DTG 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 MC74ACT245DTG?
For technical support, including MC74ACT245DTG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your MC74ACT245DTG requirements.
6.How does Aetrix verify that MC74ACT245DTG is sourced from the original manufacturer or authorized distributors?
All MC74ACT245DTG 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 MC74ACT245DTG meets industry standards.
7.What is the process for return or replacement of MC74ACT245DTG?
All MC74ACT245DTG units undergo pre-shipment inspection (PSI). If there is an issue with MC74ACT245DTG, 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 MC74ACT245DTG part is unused and in its original packaging.
Return procedure for MC74ACT245DTG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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