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Texas Instruments SN74ACT244DB
- Part No.:
- SN74ACT244DB
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74ACT244DB.pdf
- Description:
- IC BUFFER NON-INVERT 5.5V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:7,934
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Product details
Overview
SN74ACT244DB from Texas Instruments is an octal 3-state buffer/driver IC designed for bus-oriented data transmission, clock distribution, and memory address driving in 5-V TTL-compatible systems. It features dual 4-bit channels with independent active-low output enables (1OE, 2OE), 9.5 ns maximum propagation delay at 5 V, ±24 mA output drive per channel, and operation across –40°C to +85°C.
For engineers reviewing the SN74ACT244DB datasheet, SN74ACT244DB pinout, SN74ACT244DB application, or SN74ACT244DB equivalent, key selection criteria include 5-V supply tolerance (4.5–5.5 V), TTL-compatible inputs, high-drive 3-state outputs, thermal performance in SSOP-20 (RθJA = 117.2°C/W), and compatibility with LED display drivers and telecom switching networks.
Technical Context
The SN74ACT244DB implements two independent 4-bit non-inverting buffer sections, each controlled by a dedicated active-low output-enable input (1OE, 2OE). Its logic architecture supports simultaneous bidirectional bus control when paired with complementary devices, and its TTL-compatible inputs accept 2-V minimum high-level signals at 5-V VCC.
It operates strictly within 4.5 V to 5.5 V supply range, with guaranteed 24-mA sink/source capability per output under recommended conditions. The device enters high-impedance state when either OE is high, enabling clean bus sharing without contention - critical for server backplane and telecommunication switching applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - Ensures robust operation across industrial-grade 5-V rail tolerances. |
| Max Propagation Delay | 9.5 ns at 5 V - Enables reliable timing in high-speed address/data bus applications up to ~100 MHz. |
| Output Drive | ±24 mA per channel - Supports direct LED driving with external current-limiting resistors and drives heavy capacitive loads. |
| Input Compatibility | TTL-compatible - Accepts standard 5-V TTL logic levels (VIH ≥ 2 V, VIL ≤ 0.8 V) without level translation. |
| Operating Temperature | –40°C to +85°C - Qualified for commercial/industrial environments including servers and telecom infrastructure. |
| ESD Rating (HBM) | ±3000 V - Meets JEDEC JS-001 for robust handling in automated assembly and field service. |
| Thermal Resistance | RθJA = 117.2°C/W (SSOP-20) - Dictates maximum power dissipation before junction overheating in typical PCB layouts. |
Pinout & Package
SN74ACT244DB is housed in a 20-pin SSOP (Shrink Small Outline Package) with 0.65-mm lead pitch, optimized for high-density PCB layouts while maintaining hand-solderability and reflow compatibility (MSL Level-1).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1OE, 2OE | Active-low output enable inputs - Assert low to enable respective 4-bit buffer section; high places outputs in high-Z. |
| 2, 4, 6, 8, 11, 13, 15, 17 | 1A1–1A4, 2A1–2A4 | Non-inverting input terminals - Data applied here passes directly to corresponding Y outputs when OE is active. |
| 3, 5, 7, 9, 12, 14, 16, 18 | 2Y4–2Y1, 1Y4–1Y1 | Non-inverting 3-state output terminals - Deliver buffered A-input data; tri-stated when associated OE is high. |
| 10 | GND | Ground reference - Must be connected to system ground plane for stable noise margin and thermal dissipation. |
| 20 | VCC | Positive supply - Requires local 0.1-µF ceramic bypass capacitor placed adjacent to pin for transient suppression. |
Key Features
| Feature | Design Value |
|---|---|
| High-Drive Outputs | ±24 mA per channel enables direct interface to LEDs, relays, and terminated transmission lines without external drivers. |
| Dual Independent Enables | Separate 1OE and 2OE pins allow selective activation of two 4-bit groups - essential for multiplexed bus architectures. |
| TTL-Compatible Inputs | Accepts standard 5-V TTL logic thresholds (VIH ≥ 2 V, VIL ≤ 0.8 V) - eliminates need for input level shifters in mixed-logic systems. |
| Fast Switching | 9.5 ns max tPD ensures minimal skew across all eight outputs - critical for synchronous clock fanout and address strobing. |
| 3-State Output Control | True high-impedance state during power-up/down when OE tied to VCC via pullup - prevents bus contention during sequencing. |
Applications
| LED Display Drivers | Server Backplane Buffers |
|---|---|
Use Scenario: Driving 7-segment or dot-matrix LED displays in industrial HMIs and instrumentation panels. IC Role / Device Role / Timing Role: Acts as current-sinking or sourcing buffer between microcontroller GPIO and LED anodes/cathodes. Use Value: ±24 mA per channel allows direct LED drive with simple series resistors, reducing BOM count and layout complexity. | Use Scenario: Isolating and strengthening address/data signals between CPU and memory modules on high-density server motherboards. IC Role / Device Role / Timing Role: Functions as a non-inverting 3-state bus driver to prevent signal reflection and contention on shared traces. Use Value: 9.5 ns max propagation delay maintains timing margins across multi-layer backplanes operating at >50 MHz. |
| Telecom Switching Networks | Industrial I/O Expansion |
Use Scenario: Routing control signals in TDM-based voice/data switching fabric where multiple line cards share common control buses. IC Role / Device Role / Timing Role: Provides bidirectional 3-state isolation between switch controller and peripheral line interface units (LIUs). Use Value: Dual OE inputs enable precise time-slot gating and hot-swap-safe bus arbitration without signal glitches. | Use Scenario: Expanding digital I/O capacity of PLCs and motion controllers using parallel port expansion over ribbon cables. IC Role / Device Role / Timing Role: Serves as a level-translating and noise-immune buffer between MCU and remote I/O modules. Use Value: TTL-compatible inputs tolerate marginal signal integrity on long cables; 3-state outputs support daisy-chained configurations. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal 3-state buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT244DW | SOIC-20 package; higher RθJA (101.2°C/W); identical electrical specs and pinout. | Better thermal mass but larger footprint; less suitable for ultra-dense layouts. | Select SN74ACT244DW only when SOIC hand-soldering or legacy board compatibility is required. |
| SN74LVC244A | 3.3-V only (1.65–3.6 V); lower drive (±24 mA @ 3.3 V); CMOS inputs; not TTL-compatible. | Requires level translation when interfacing with 5-V TTL systems; unsuitable for direct replacement. | Choose SN74LVC244A only in new 3.3-V designs where voltage scaling and lower power are prioritized over 5-V interoperability. |
Compared with SN74ACT244DW and SN74LVC244A, the SN74ACT244DB offers optimal density and thermal performance in 5-V TTL systems - its SSOP-20 footprint saves >40% board area versus SOIC, while maintaining full functional and pinout compatibility with the DW variant.
Availability
SN74ACT244DB is available at Aetrix Electronics and suitable for LED display drivers, server backplane buffers, and telecom switching networks requiring stable component supply across extended production lifecycles.
Supply support for SN74ACT244DB 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 delivering analog and embedded processing solutions, with over 90 years of innovation in logic, power, and signal chain technologies.
The SNx4ACT244 product line was engineered for high-reliability 5-V bus interfacing - targeting memory address drivers, clock distribution, and 3-state transceivers in industrial computing and communications infrastructure.
FAQ
What is the maximum supply voltage rating for SN74ACT244DB?
The absolute maximum VCC rating for SN74ACT244DB is 7 V, but the recommended operating range is strictly 4.5 V to 5.5 V. Operation outside this window may cause parametric degradation or latch-up. The SN74ACT244DB is designed for nominal 5-V systems and must not be operated continuously above 5.5 V in production use.
Does SN74ACT244DB support 3.3-V input logic levels?
No - SN74ACT244DB inputs are TTL-compatible, requiring VIH ≥ 2.0 V at 5-V VCC. While it accepts inputs up to 5.5 V, it does not guarantee recognition of 3.3-V logic highs (typically ~2.4 V) across temperature and process variation. For 3.3-V systems, SN74LVC244A or level-shifting circuitry is required instead of SN74ACT244DB.
How should unused inputs be handled on SN74ACT244DB?
All unused inputs on SN74ACT244DB must be tied to either VCC or GND - floating inputs cause increased ICC, noise susceptibility, and potential oscillation. TI recommends connecting unused A inputs to GND (for low-power idle state) and unused OE inputs to VCC (to ensure outputs remain in high-Z). This practice is explicitly required per TI application report SLVA675.
What is the thermal resistance (RθJA) of SN74ACT244DB in its SSOP package?
The junction-to-ambient thermal resistance (RθJA) for SN74ACT244DB in the DB (SSOP-20) package is 117.2°C/W under standard JEDEC test conditions (JESD51-2). This value assumes a 1-inch² copper pad with two internal layers; actual board-level performance depends on PCB copper area, airflow, and nearby heat sources - derating is required above 70°C ambient.
Can SN74ACT244DB drive LEDs directly without external current-limiting components?
No - SN74ACT244DB requires external current-limiting resistors for LED driving. Although it delivers ±24 mA per output, continuous operation at that level exceeds safe LED forward current and risks exceeding the device's total package power limit. A 1-kΩ resistor at 5 V limits current to ~5 mA, aligning with both LED ratings and SN74ACT244DB's thermal design envelope.
SN74ACT244DB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ACT
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- Buffer, Non-Inverting
- Number of Elements:
- 2
- Number of Bits per Element:
- 4
- 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
SN74ACT244DB FAQ
1.How can I place an order for SN74ACT244DB through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ACT244DB 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 SN74ACT244DB reliable?
The price and inventory of SN74ACT244DB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ACT244DB is usually 5 days.
3.What payment methods are accepted for SN74ACT244DB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74ACT244DB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74ACT244DB?
SN74ACT244DB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ACT244DB 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 SN74ACT244DB?
For technical support, including SN74ACT244DB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ACT244DB requirements.
6.How does Aetrix verify that SN74ACT244DB is sourced from the original manufacturer or authorized distributors?
All SN74ACT244DB 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 SN74ACT244DB meets industry standards.
7.What is the process for return or replacement of SN74ACT244DB?
All SN74ACT244DB units undergo pre-shipment inspection (PSI). If there is an issue with SN74ACT244DB, 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 SN74ACT244DB part is unused and in its original packaging.
Return procedure for SN74ACT244DB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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