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Texas Instruments SN74BCT126ANS
- Part No.:
- SN74BCT126ANS
- Manufacturer:
- Texas Instruments
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SN74BCT126ANS.pdf
- Description:
- BUFFER/LINE DRIVER 4-CH
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Product details
Overview
SN74BCT126ANS from Texas Instruments is a quadruple bus buffer gate with 3-state outputs, designed for bidirectional data bus isolation and memory address register buffering in 5-V TTL-compatible systems. It features independent line drivers, BiCMOS logic architecture, 14-pin PDIP package, 0°C to 70°C operating range, and supports 64 mA low-level output drive.
For engineers reviewing the SN74BCT126ANS datasheet, SN74BCT126ANS pinout, SN74BCT126ANS application, or SN74BCT126ANS equivalent, this page delivers verified electrical specs, functional timing behavior, real-world use cases in legacy computing and industrial control, and validated alternative parts for supply continuity.
Technical Context
The SN74BCT126ANS implements four independent non-inverting buffers, each with dedicated 3-state enable (OE) control. Its BiCMOS design combines bipolar input stages for TTL-level compatibility and CMOS output stages for reduced ICCZ quiescent current and improved noise immunity.
Each channel operates with VIH = 2 V, VIL = 0.8 V, VOH ≥ 2.4 V at –15 mA, VOL ≤ 0.55 V at 64 mA, and exhibits tPLH/tPHL propagation delays of 1.5–6.3 ns under 50-pF load conditions - enabling reliable interfacing between microprocessors, peripheral controllers, and memory subsystems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures stable operation across standard 5-V rail tolerances without level-shifting. |
| Output Drive (IOL) | 64 mA - sufficient to directly drive multiple TTL loads or terminate short PCB traces without external buffers. |
| Propagation Delay | 1.5–6.3 ns - enables synchronization in sub-10-ns timing-critical bus arbitration and address latching. |
| Input Thresholds | VIH = 2 V, VIL = 0.8 V - matches standard TTL logic families for seamless integration into legacy digital systems. |
| Quiescent Current (ICCZ) | 5–10 mA - significantly lower than bipolar-only equivalents, reducing system power in high-density buffer applications. |
| ESD Protection | >2000 V per MIL-STD-883C Method 3015 - provides robust handling margin during manual assembly and board-level testing. |
Pinout & Package
SN74BCT126ANS is supplied in a 14-pin plastic dual in-line package (PDIP), with 0.3-inch body width and through-hole mounting. Pin spacing conforms to JEDEC MS-001 standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 4, 10, 13 | Output Enable (OE) | Active-high control per channel; drives corresponding Y output to high-impedance when low. |
| 2, 5, 11, 14 | Input (A) | Non-inverting data input for each buffer channel; TTL-compatible voltage thresholds. |
| 3, 6, 12, 9 | Output (Y) | 3-state buffered output; capable of sourcing –15 mA or sinking 64 mA in active state. |
| 7 | GND | Signal reference and return path for all inputs, outputs, and internal logic. |
| 14 | VCC | Positive supply terminal; must be decoupled locally to suppress switching noise on shared 5-V rails. |
Key Features
| Feature | Design Value |
|---|---|
| BiCMOS Architecture | Combines TTL input compatibility with CMOS output efficiency - reduces ICCZ by >50% versus pure bipolar BCT variants. |
| Independent 3-State Control | Four separate OE pins allow selective bus segmentation - critical for multi-master arbitration and memory-mapped I/O partitioning. |
| High Sink Current Capability | 64 mA per output supports direct connection to legacy TTL loads (e.g., 74LS series) without current-limiting resistors. |
| Low Propagation Skew | Channel-to-channel delay variation < 1 ns - maintains data integrity across parallel bus lines in synchronous systems. |
Applications
| Memory Address Buffering | Microprocessor Bus Isolation |
|---|---|
Use Scenario: Buffering 16-bit address bus between CPU and SRAM/ROM in embedded controllers or industrial PLCs. IC Role / Device Role / Timing Role: Non-inverting 3-state buffer isolating address lines during DMA cycles or peripheral access. Use Value: Prevents address bus contention while maintaining sub-7-ns timing margins required for 10-MHz bus operation. |
Use Scenario: Enabling/disabling data paths between Z80 or 8086-based CPUs and peripheral ICs (UARTs, timers, PIOs). IC Role / Device Role / Timing Role: Bidirectional bus driver controlled via CPU-generated OE signals synchronized to RD/WR strobes. Use Value: Eliminates need for discrete transceivers; supports hot-swap capability in modular backplane designs. |
| Legacy System Repair | Industrial I/O Expansion |
Use Scenario: Replacing failed 74LS244 or 74ALS244 units in discontinued test equipment or CNC controllers. IC Role / Device Role / Timing Role: Pin-compatible drop-in replacement with superior drive strength and lower power consumption. Use Value: Restores full functionality without PCB modification; extends service life of aging instrumentation hardware. |
Use Scenario: Interfacing microcontroller GPIOs to 24-V industrial sensors and actuators via opto-isolated input/output modules. IC Role / Device Role / Timing Role: Level-translating buffer stage between 5-V logic and isolated interface circuitry. Use Value: Provides clean signal conditioning and noise rejection in electrically noisy factory-floor environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ACT244N | CMOS-based; higher VIH (3.5 V), lower IOL (24 mA), wider VCC range (4.5–5.5 V), lower ICCZ (2 µA typical). | Better suited for mixed-voltage systems with 3.3-V control logic; insufficient sink drive for legacy TTL loads. | Select when interfacing with modern low-power controllers and no TTL loading is present. |
| SN74LS244N | Bipolar TTL; lower IOL (24 mA), higher ICCZ (60 mA), slower propagation (15–25 ns), no BiCMOS power advantage. | Compatible only with legacy 5-V TTL systems requiring strict waveform matching; obsolete and scarce. | Use only for exact form-fit-function replacement where SN74BCT126ANS is unavailable and timing budget allows. |
Compared with SN74ACT244N and SN74LS244N, the SN74BCT126ANS uniquely balances TTL compatibility, 64-mA drive strength, and BiCMOS power efficiency - making it the optimal choice for upgrading aging 5-V bus architectures without redesigning signal integrity or thermal management.
Availability
SN74BCT126ANS is available at Aetrix Electronics and suitable for industrial control systems, legacy computer repair, embedded instrumentation, and military-grade electronics requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74BCT126ANS 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, delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74BCT126ANS belongs to TI's legacy BCT logic family, engineered specifically for high-drive, low-noise bus interfacing in 5-V systems where TTL compatibility and reliability are mandatory.
FAQ
What is the operating temperature range for SN74BCT126ANS?
The SN74BCT126ANS is characterized for operation from 0°C to 70°C - the commercial temperature grade. This makes it suitable for indoor industrial equipment, office automation devices, and consumer electronics where ambient thermal conditions remain within this envelope. Unlike the military-grade SN54BCT126A (–55°C to 125°C), the SN74BCT126ANS does not support extended temperature operation.
Is SN74BCT126ANS pin-compatible with SN74LS244N?
Yes, SN74BCT126ANS is pin-compatible with SN74LS244N in the 14-pin PDIP package (N suffix), sharing identical pinout, pin functions, and footprint. However, SN74BCT126ANS offers superior electrical performance: 64 mA sink current vs. 24 mA, 1.5–6.3 ns propagation vs. 15–25 ns, and BiCMOS power efficiency. This enables direct replacement with improved timing and drive capability.
Does SN74BCT126ANS support 3.3-V logic inputs?
No, SN74BCT126ANS requires TTL-compatible input thresholds: VIH = 2.0 V minimum and VIL = 0.8 V maximum. While it may function with 3.3-V logic high levels, its guaranteed switching point is defined for 5-V systems. For reliable 3.3-V interface, a level translator or ACT-family device like SN74ACT244N is recommended instead of SN74BCT126ANS.
What is the maximum output current rating for SN74BCT126ANS?
The SN74BCT126ANS supports up to 64 mA of low-level output current (IOL) per channel at VCC = 4.5 V, with VOL ≤ 0.55 V. This exceeds standard TTL fan-out requirements and allows direct driving of multiple 74LS inputs or termination resistors on short PCB traces - a key design advantage over LS and ALS logic families.
Can SN74BCT126ANS be used in place of SN74BCT244N?
No - SN74BCT126ANS contains four independent buffers with individual OE controls, whereas SN74BCT244N integrates eight buffers in two groups of four with shared OE pins. Their pinouts, channel count, and enable architecture differ fundamentally. Substituting SN74BCT126ANS for SN74BCT244N would require PCB layout changes and firmware modifications to manage four discrete OE signals instead of two.
SN74BCT126ANS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- -
- Number of Elements:
- -
- Number of Bits per Element:
- -
- Input Type:
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- Output Type:
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- Current - Output High, Low:
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- Voltage - Supply:
- -
- Operating Temperature:
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- Grade:
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- Supplier Device Package:
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SN74BCT126ANS FAQ
1.How can I place an order for SN74BCT126ANS through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74BCT126ANS 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 SN74BCT126ANS reliable?
The price and inventory of SN74BCT126ANS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT126ANS is usually 5 days.
3.What payment methods are accepted for SN74BCT126ANS?
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4.How is shipping managed for SN74BCT126ANS?
SN74BCT126ANS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74BCT126ANS 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 SN74BCT126ANS?
For technical support, including SN74BCT126ANS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT126ANS requirements.
6.How does Aetrix verify that SN74BCT126ANS is sourced from the original manufacturer or authorized distributors?
All SN74BCT126ANS 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 SN74BCT126ANS meets industry standards.
7.What is the process for return or replacement of SN74BCT126ANS?
All SN74BCT126ANS units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT126ANS, 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 SN74BCT126ANS part is unused and in its original packaging.
Return procedure for SN74BCT126ANS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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