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Texas Instruments SN74BCT544NT
- Part No.:
- SN74BCT544NT
- Manufacturer:
- Texas Instruments
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- -
- Datasheet:
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SN74BCT544NT.pdf
- Description:
- REGISTERED BUS TRANSCEIVER
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Product details
Overview
SN74BCT544NT from Texas Instruments is an octal registered transceiver with 3-state inverting outputs, designed for bidirectional data flow control between two 8-bit buses. It features dual independent latch-enable (LEAB/LEBA) and output-enable (OEAB/OEBA) controls, operates at 4.5–5.5 V, supports 0°C to 70°C ambient, and delivers 64 mA low-level output drive per pin.
For engineers reviewing the SN74BCT544NT datasheet, SN74BCT544NT pinout, SN74BCT544NT application, or SN74BCT544NT equivalent, this device is selected for high-speed bus isolation, temporary data staging in legacy TTL-compatible systems, and controlled direction switching in industrial backplane interfaces where BiCMOS power efficiency and ESD robustness (>2000 V) are critical.
Technical Context
The SN74BCT544NT implements two independent 8-bit D-type latch banks - A-to-B and B-to-A - each with dedicated CE, LE, and OE inputs enabling precise timing control of data capture and output enablement. Its BiCMOS architecture reduces ICCZ quiescent current while maintaining TTL-compatible input thresholds and 3-state output behavior.
It supports simultaneous or staggered register loading via LEAB/LEBA transitions, with output inversion applied on both A→B and B→A paths. The device requires CEAB low for A-to-B operation and CEBA low for B-to-A operation; all outputs enter high-impedance state when respective OE inputs are high or VCC is unpowered.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures compatibility with standard 5-V TTL and mixed-voltage logic systems without level-shifting. |
| Operating Temperature | 0°C to 70°C - qualified for commercial-grade embedded and industrial control applications, not extended/military range. |
| Output Drive (IOL) | 64 mA per pin - sufficient to drive multiple TTL loads or terminate short stubs in parallel bus architectures. |
| Propagation Delay (tPLH/tPHL) | 2.4–10.3 ns - enables sub-100 MHz bus handshaking in synchronous register-to-register transfers. |
| Input Clamp Current | –18 mA - provides robust protection against transient overvoltage on control or data lines per MIL-STD-883C. |
| ESD Rating | >2000 V HBM - meets minimum requirement for handling in non-ESD-controlled assembly environments. |
| ICCZ Quiescent Current | 9–15 mA - reduced versus older bipolar TTL, lowering standby power in always-on bus interface stages. |
Pinout & Package
SN74BCT544NT is supplied in a 24-pin plastic dual-in-line package (PDIP-NT), with 0.3-inch body width and through-hole mounting. Pin 1 is marked by a notch or dot; pin numbering follows standard DIP convention (counterclockwise from top-left).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | LEBA | Latch-enable for B-to-A register - low enables transparency; rising edge captures B-bus data into A-latches. |
| 2 | OEBA | Output-enable for B-to-A path - low activates inverted 3-state outputs A1–A8; high disables them. |
| 3–10 | A1–A8 | Data inputs/outputs for A-side bus - function as inputs when OEBA high, outputs when OEBA low (inverted). |
| 11 | CEAB | Chip-enable for A-to-B path - must be low to allow A-data latching or B-output activation. |
| 12 | GND | Ground reference - common return for all internal logic and output drivers. |
| 13 | VCC | Positive supply - powers BiCMOS circuitry; decoupling capacitor required near pin for noise immunity. |
| 14 | CEBA | Chip-enable for B-to-A path - must be low to allow B-data latching or A-output activation. |
| 15–22 | B1–B8 | Data inputs/outputs for B-side bus - function as inputs when OEAB high, outputs when OEAB low (inverted). |
| 23 | LEAB | Latch-enable for A-to-B register - low enables transparency; rising edge captures A-bus data into B-latches. |
| 24 | OEAB | Output-enable for A-to-B path - low activates inverted 3-state outputs B1–B8; high disables them. |
Key Features
| Feature | Design Value |
|---|---|
| Back-to-back registers | Enables full-duplex staging: A-bus data can be captured and held while B-bus data is independently latched and output. |
| 3-state inverting outputs | Allows bidirectional bus sharing without external direction-control logic; inversion is fixed and inherent to signal path. |
| Power-up high-impedance | Prevents bus contention during power sequencing - all outputs remain Hi-Z until VCC stabilizes and OE is asserted. |
| BiCMOS process | Reduces ICCZ by >50% vs. equivalent bipolar TTL, cutting static power in always-enabled interface stages. |
| Independent CE/LE/OE per direction | Supports asymmetric timing - e.g., A→B latch can occur while B→A outputs remain active or disabled. |
Applications
| Industrial Backplane Interface | Legacy System Bus Isolation |
|---|---|
|
Use Scenario: Isolating CPU address/data bus from peripheral expansion slots in programmable logic controllers. IC Role / Device Role / Timing Role: Acts as direction-controlled, registered buffer between microprocessor and I/O modules, synchronizing handshakes across asynchronous clock domains. Use Value: Prevents bus contention during hot-swap events and enables deterministic read/write timing via latch-enable edge control. |
Use Scenario: Interfacing modern FPGA-based controllers to vintage 8-bit ISA-style peripherals requiring TTL-level signaling. IC Role / Device Role / Timing Role: Provides level-compatible, registered transceivers that absorb setup/hold timing skews between mismatched logic families. Use Value: Eliminates need for discrete glue logic and external latches, reducing PCB area and signal integrity risk on long parallel traces. |
| Test Equipment Data Capture | Programmable Logic Staging |
|
Use Scenario: Capturing parallel sensor data streams in automated test equipment before serial conversion or storage. IC Role / Device Role / Timing Role: Serves as synchronized input latch bank, freezing 8-bit analog-to-digital converter outputs on trigger edges. Use Value: Enables precise time-aligned sampling across multiple channels using shared LEAB/LEBA signals and independent OE control. |
Use Scenario: Holding configuration bits between CPLD reconfiguration cycles in field-upgradable embedded systems. IC Role / Device Role / Timing Role: Functions as nonvolatile shadow register - retains last valid state during reprogramming windows. Use Value: Maintains functional I/O states during partial reconfiguration, avoiding system reset or glitch-induced faults. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal registered transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT544N | AC-family CMOS; 4.5–5.5 V supply; 24 mA IOL; faster tPLH (1.5 ns typ); no BiCMOS ICCZ reduction. | Lower drive strength suits low-power, high-speed point-to-point links; unsuitable for driving multiple TTL loads. | Select SN74ACT544N when speed > drive is prioritized and bus loading is light. |
| 74F544N | F-family bipolar TTL; 4.5–5.5 V; 20 mA IOL; higher ICCZ (35 mA); 10 ns typical propagation delay. | Higher power consumption limits use in thermally constrained enclosures; less ESD robustness (1500 V HBM). | Choose 74F544N only if legacy F-series board compatibility is mandatory and thermal margin exists. |
Compared with SN74ACT544N and 74F544N, the SN74BCT544NT uniquely balances moderate speed, high drive capability, and low quiescent current - making it optimal for legacy bus interfaces where load-driving capacity and power efficiency are jointly critical.
Availability
SN74BCT544NT is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy system upgrades, test equipment data capture, and programmable logic staging requiring stable component supply and long-term obsolescence management support.
Supply support for SN74BCT544NT 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 founded in 1930, specializing in analog, embedded processing, and logic solutions with broad industrial, automotive, and communications reach.
The SN74BCT544NT belongs to TI's BCT (Bipolar-CMOS Transceiver) logic family, engineered specifically for high-drive, low-quiescent-current bidirectional bus interfacing in 5-V TTL-compatible systems.
FAQ
What is the operating temperature range for the SN74BCT544NT?
The SN74BCT544NT is characterized for commercial operation from 0°C to 70°C. This range is explicitly defined in the datasheet's recommended operating conditions table and distinguishes it from the military-grade SN54BCT544 variant, which operates from –55°C to 125°C. The NT suffix confirms the PDIP packaging and commercial temperature grade, making SN74BCT544NT appropriate for non-extreme environmental applications such as factory automation panels and office equipment.
Does the SN74BCT544NT support true bidirectional data flow without external direction control?
Yes, the SN74BCT544NT supports fully independent bidirectional data flow using dedicated control inputs: CEAB/LEAB/OEAB govern A-to-B transfer, while CEBA/LEBA/OEBA manage B-to-A transfer. No external direction line is needed because each path has its own latch-enable and output-enable signals. This architecture allows simultaneous or staggered registration in both directions - a key capability confirmed in the function table and logic diagram of the SN74BCT544NT datasheet.
Is the SN74BCT544NT pin-compatible with other 24-pin octal transceivers like the 74LS245?
No, the SN74BCT544NT is not pin-compatible with the 74LS245 or other octal bus transceivers. Its pinout is unique: it allocates separate pins for LEAB, LEBA, OEAB, OEBA, CEAB, and CEBA - totaling six control inputs - whereas the 74LS245 uses only DIR and OE. The SN74BCT544NT pin assignment (e.g., LEBA on pin 1, OEBA on pin 2, CEAB on pin 11) differs fundamentally from standard transceiver layouts, requiring custom PCB layout.
What does "3-state inverting outputs" mean for the SN74BCT544NT?
"3-state inverting outputs" means each of the eight B- or A-side outputs can assume one of three electrical states: logic HIGH, logic LOW, or high-impedance (Hi-Z), and the output logic level is always the inverse of the latched input. For example, when OEAB is low and CEAB is low, B1–B8 reflect the inverted values of A1–A8. When OEAB goes high, all B outputs disconnect electrically from the bus - a feature essential for shared-bus arbitration. This behavior is verified in the function table and timing diagrams of the SN74BCT544NT datasheet.
Why does the SN74BCT544NT specify different IOL ratings for SN54BCT544 and SN74BCT544?
The SN74BCT544NT specifies 64 mA low-level output current (IOL) because it is the commercial-grade version (0°C to 70°C), while the SN54BCT544 specifies 96 mA for the military-grade part (–55°C to 125°C). The derating reflects guaranteed performance margins across temperature extremes: the SN74BCT544NT's 64 mA is tested and warranted under commercial conditions, ensuring reliable drive into multiple TTL loads without thermal throttling. This distinction is clearly tabulated in the absolute maximum ratings section of the SN74BCT544NT datasheet.
SN74BCT544NT Specifications
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- Manufacturer:
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SN74BCT544NT FAQ
1.How can I place an order for SN74BCT544NT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74BCT544NT 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 SN74BCT544NT reliable?
The price and inventory of SN74BCT544NT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT544NT is usually 5 days.
3.What payment methods are accepted for SN74BCT544NT?
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4.How is shipping managed for SN74BCT544NT?
SN74BCT544NT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74BCT544NT 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 SN74BCT544NT?
For technical support, including SN74BCT544NT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT544NT requirements.
6.How does Aetrix verify that SN74BCT544NT is sourced from the original manufacturer or authorized distributors?
All SN74BCT544NT 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 SN74BCT544NT meets industry standards.
7.What is the process for return or replacement of SN74BCT544NT?
All SN74BCT544NT units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT544NT, 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 SN74BCT544NT part is unused and in its original packaging.
Return procedure for SN74BCT544NT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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