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Texas Instruments SN74HCT244DBR
- Part No.:
- SN74HCT244DBR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74HCT244DBR.pdf
- Description:
- IC BUF NON-INVERT 5.5V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:5,343
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Product details
Overview
SN74HCT244DBR from Texas Instruments is an octal non-inverting 3-state buffer/line driver IC designed for bus-oriented memory address and clock signal buffering. It operates at 4.5–5.5 V, delivers ±6 mA output drive per channel, exhibits 13 ns typical propagation delay (tpd) at 5.5 V with 50 pF load, and supports TTL-compatible inputs. It is used in server backplanes to isolate and strengthen address/data bus signals between CPU and memory modules.
For engineers reviewing the SN74HCT244DBR datasheet, SN74HCT244DBR pinout, SN74HCT244DBR application, or SN74HCT244DBR equivalent, key selection criteria include 3-state output control timing (ten/tdis ≤ 48 ns), high-current drive capability (±6 mA), low quiescent current (≤80 µA), and SSOP-20 package compatibility with dense PCB layouts in telecom and industrial control systems.
Technical Context
The SN74HCT244DBR implements two independent 4-bit non-inverting buffers, each with dedicated active-low output-enable (OE) control. Its CMOS HCT logic family ensures TTL-voltage compatibility while maintaining CMOS power efficiency. All inputs tolerate standard TTL thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V) across –40°C to 85°C ambient operation.
When OE is low, data passes transparently from A-inputs to Y-outputs; when OE is high, all eight outputs enter high-impedance state-enabling bidirectional bus sharing without contention. The device features balanced rise/fall times (tr/tf ≤ 16 ns at 5.5 V, CL = 50 pF) and input leakage ≤1 µA, supporting stable operation in noise-sensitive digital interfaces.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply voltage | 4.5 V to 5.5 V - compatible with standard 5 V logic rails and tolerant of supply ripple up to ±0.5 V. |
| Output drive | ±6 mA per channel at 5 V - sufficient to directly drive 15 LSTTL loads without external amplification. |
| Propagation delay | 13 ns typical (tpd) at VCC = 5.5 V, CL = 50 pF - enables reliable operation in 30 MHz+ bus cycles. |
| Quiescent current | 80 µA maximum ICC - minimizes standby power in always-on system management circuits. |
| Input compatibility | TTL-voltage compatible (VIH ≥ 2.0 V, VIL ≤ 0.8 V) - interoperable with legacy 74LS and microcontroller GPIOs. |
| 3-state enable time | 19 ns typical (ten) at VCC = 5.5 V, CL = 50 pF - ensures fast bus arbitration in multi-master systems. |
| ESD rating | ±2000 V HBM - meets industrial handling requirements without additional protection circuitry. |
Pinout & Package
SN74HCT244DBR uses a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch, body size 7.2 mm × 5.3 mm, and overall footprint 7.2 mm × 7.8 mm. It is RoHS-compliant, moisture sensitivity level 1, and rated for –40°C to +85°C operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 19 | 1OE, 2OE | Active-low output-enable controls for Group 1 (pins 2–9) and Group 2 (pins 11–18); tied high disables both groups. |
| 2, 4, 6, 8 | 1A1–1A4 | Group 1 input channels - accept TTL-level signals for buffering to corresponding Y outputs. |
| 3, 5, 7, 9 | 2Y4–2Y1 | Group 1 output channels - drive bus lines or memory address registers with 3-state capability. |
| 10 | GND | Ground reference for logic and power return - must be low-impedance connection to minimize noise coupling. |
| 11, 13, 15, 17 | 2A1–2A4 | Group 2 input channels - electrically isolated from Group 1; support independent bus segment control. |
| 12, 14, 16, 18 | 1Y4–1Y1 | Group 2 output channels - provide mirrored functionality to Group 1 with separate OE control. |
| 20 | VCC | Positive supply pin - requires local 0.1 µF ceramic bypass capacitor placed within 5 mm of the pin. |
Key Features
| Feature | Design Value |
|---|---|
| Two independent 4-bit groups | Enables selective bus isolation: one group can drive while the other remains tri-stated, reducing contention risk. |
| High-current 3-state outputs | ±6 mA drive per output allows direct interface to unterminated traces up to 10 cm on FR-4 PCBs. |
| Low ICC quiescent consumption | 80 µA max ICC supports energy-sensitive applications like fanless embedded controllers and remote I/O nodes. |
| TTL-compatible input thresholds | Eliminates need for level-shifting circuitry when interfacing with legacy 74LS, microcontrollers, or FPGA I/O banks. |
| Fast enable/disable timing | ten/tdis ≤ 48 ns ensures sub-20 ns bus turnaround - critical for high-throughput memory-mapped peripherals. |
Applications
| Server Memory Bus Isolation | LED Display Column Driver |
|---|---|
|
Use Scenario: Buffering CPU-generated memory address signals before routing to multiple DDR SDRAM modules on a dense backplane. IC Role / Device Role / Timing Role: Non-inverting 3-state buffer that isolates address lines during memory refresh cycles and prevents bus contention. Use Value: Enables clean signal integrity over 8-layer PCB traces up to 15 cm long while supporting 100 MHz address strobes. |
Use Scenario: Driving common-anode LED display columns in industrial HMIs where microcontroller GPIO current is insufficient. IC Role / Device Role / Timing Role: High-current line driver translating low-voltage MCU outputs into 6 mA sink capability per column. Use Value: Eliminates need for discrete transistor arrays; reduces BOM count by 8× and improves thermal margin vs. discrete solutions. |
| Network Switch Control Plane Interface | Industrial I/O Expander Back-End |
|
Use Scenario: Interfacing ARM-based switch controller to CPLD-configured PHY management buses with shared control lines. IC Role / Device Role / Timing Role: Bidirectional bus buffer enabling read/write access to multiple PHY registers via time-multiplexed addressing. Use Value: Provides glitch-free bus handover using independent OE pins, preventing register corruption during hot-plug events. |
Use Scenario: Extending GPIO count of a PLC main controller to manage 16-channel digital input modules with ESD-prone field wiring. IC Role / Device Role / Timing Role: Input buffer with high-impedance isolation protecting MCU pins from transients induced on 24 V DC field lines. Use Value: Input leakage ≤1 µA ensures stable logic levels even with 100 kΩ pull-up networks; supports IEC 61000-4-2 Level 3 immunity. |
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 |
|---|---|---|---|
| SN74HCT244PW | TSSOP-20 package (6.5 mm × 6.4 mm), same electrical specs, MSL Level-1, rated –40°C to 125°C. | Better thermal performance (RθJA = 131.8°C/W vs. 122.7°C/W) and wider temperature range - preferred for extended-temperature industrial use. | Select SN74HCT244PW when board space permits smaller footprint and operating temperature exceeds 85°C. |
| 74LCX244MTCX | Lower VCC range (2.0–3.6 V), 3.3 V–optimized, 24 mA drive, faster tpd (5.5 ns), but not TTL-compatible. | Designed for mixed-voltage 3.3 V systems; incompatible with 5 V buses unless level-shifted - unsuitable for direct SN74HCT244DBR replacement. | Choose 74LCX244MTCX only in new 3.3 V designs requiring higher speed and lower voltage; not a drop-in substitute. |
Compared with SN74HCT244PW and 74LCX244MTCX, SN74HCT244DBR offers optimal balance of 5 V compatibility, SSOP-20 mechanical fit, and proven reliability in legacy server and telecom infrastructure - making it the preferred choice for cost-sensitive, volume-manufactured 5 V systems requiring no redesign.
Availability
SN74HCT244DBR is available at Aetrix Electronics and suitable for servers, LED displays, and network switches requiring stable component supply across long production lifecycles and industrial temperature ranges.
Supply support for SN74HCT244DBR 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 specializing in analog, embedded processing, and logic solutions with over 50 years of innovation in industrial, automotive, and communications markets.
The SN74HCT244DBR belongs to TI's HCT logic family, engineered for seamless integration between TTL and CMOS systems - specifically targeting memory address buffering, clock distribution, and bus isolation in high-density digital systems.
FAQ
What is the maximum operating temperature for SN74HCT244DBR?
The SN74HCT244DBR is rated for operation from –40°C to +85°C ambient temperature. This specification is confirmed in TI's official orderable addendum and applies to the DB (SSOP-20) package variant. Exceeding 85°C may cause parametric shift in VOH/VOL and increased ICC, so thermal design must ensure junction temperature stays below 150°C under worst-case power dissipation.
Does SN74HCT244DBR support 3.3 V logic inputs?
No, SN74HCT244DBR does not reliably support 3.3 V logic inputs. Its input thresholds are TTL-compatible (VIH ≥ 2.0 V min, VIL ≤ 0.8 V max at VCC = 4.5–5.5 V), meaning a 3.3 V high signal falls within spec, but marginal noise margins and potential VIH violation under VCC = 4.5 V require verification. For guaranteed 3.3 V interfacing, use a level shifter or select a 3.3 V–native buffer like SN74LVC244A.
How many output-enable (OE) pins does SN74HCT244DBR have?
SN74HCT244DBR has two independent active-low output-enable pins: 1OE (pin 1) controls outputs 1Y1–1Y4 (pins 18, 16, 14, 12), and 2OE (pin 19) controls outputs 2Y1–2Y4 (pins 9, 7, 5, 3). This dual-OE architecture allows independent gating of two 4-bit data paths - essential for multiplexed bus architectures and partial bus isolation.
Can SN74HCT244DBR drive LEDs directly?
Yes, SN74HCT244DBR can drive LEDs directly in sink configuration: connect LED anode to VCC (5 V) and cathode to any Y-output (e.g., pin 12), with current limited by series resistor. At VO = 0.4 V (max VOL @ 6 mA), a 680 Ω resistor yields ~6.5 mA - within rated output capability. Avoid sourcing mode (LED cathode to GND) due to weaker VOH drive (3.7 V min @ –6 mA).
What is the recommended bypass capacitor for SN74HCT244DBR?
Texas Instruments specifies a 0.1 µF ceramic capacitor placed as close as possible to the VCC pin (pin 20) and GND (pin 10) of SN74HCT244DBR. This value is validated for noise suppression across the 1–100 MHz switching spectrum generated by its 13 ns tpd and ±6 mA edges. Use X7R dielectric, 0603 or 0805 case size, and keep trace length under 5 mm for optimal high-frequency decoupling.
SN74HCT244DBR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 6mA, 6mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74HCT244DBR FAQ
1.How can I place an order for SN74HCT244DBR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCT244DBR 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 SN74HCT244DBR reliable?
The price and inventory of SN74HCT244DBR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCT244DBR is usually 5 days.
3.What payment methods are accepted for SN74HCT244DBR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HCT244DBR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HCT244DBR?
SN74HCT244DBR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCT244DBR 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 SN74HCT244DBR?
For technical support, including SN74HCT244DBR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCT244DBR requirements.
6.How does Aetrix verify that SN74HCT244DBR is sourced from the original manufacturer or authorized distributors?
All SN74HCT244DBR 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 SN74HCT244DBR meets industry standards.
7.What is the process for return or replacement of SN74HCT244DBR?
All SN74HCT244DBR units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCT244DBR, 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 SN74HCT244DBR part is unused and in its original packaging.
Return procedure for SN74HCT244DBR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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