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Texas Instruments SN74BCT126AN
- Part No.:
- SN74BCT126AN
- Manufacturer:
- Texas Instruments
- Package:
- 14-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74BCT126AN.pdf
- Description:
- IC BUF NON-INVERT 5.5V 14DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,825
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Product details
Overview
SN74BCT126AN 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 TTL-compatible 5-V systems. It features four independent non-inverting buffers, each controlled by a dedicated output-enable (OE) input, supports 128 mA low-level output drive, operates from 0°C to 70°C, and uses a 14-pin plastic DIP (N) package.
For engineers reviewing the SN74BCT126AN datasheet, SN74BCT126AN pinout, SN74BCT126AN application, or SN74BCT126AN equivalent, this page delivers verified electrical specs (VOL = 0.42 V @ IOL = 64 mA), timing parameters (tPLH = 1.5 ns min), thermal limits, and real-world substitution guidance - all grounded in TI's SCBS252A datasheet and official packaging data.
Technical Context
The SN74BCT126AN implements BiCMOS logic architecture to achieve low ICCZ (5–10 mA) while maintaining TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2 V) and robust 5-V operation. Its 3-state outputs enable time-multiplexed bus sharing without contention.
Each of the four channels operates independently: an active-high OE input disables the corresponding Y output into high-impedance (IOZH/IOZL ≤ ±50 µA), while A-to-Y propagation delay ranges from 1.5 ns (tPLH min) to 6.3 ns (tPLH max) under 50-pF load conditions at 25°C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage (VCC) | 4.5 V to 5.5 V - ensures compatibility with standard 5-V TTL and CMOS systems without level-shifting. |
| Low-Level Output Voltage (VOL) | 0.42 V max @ IOL = 64 mA - guarantees solid logic-low margin under heavy capacitive bus loads. |
| Propagation Delay (tPLH) | 1.5 ns min / 6.3 ns max @ CL = 50 pF - enables reliable operation in sub-10-ns timing-critical address/data paths. |
| Output Drive (IOL) | 64 mA - sufficient to drive multiple TTL inputs or moderate PCB trace capacitance without external buffers. |
| Input Clamp Current (IIK) | –18 mA - protects against transient overvoltage on inputs during hot-swap or ESD events. |
| Quiescent Current (ICCZ) | 5–10 mA - low standby power in 3-state mode improves system-level power efficiency vs. older bipolar buffers. |
Pinout & Package
SN74BCT126AN is supplied in a 14-pin plastic dual in-line package (PDIP-N), with 0.3-inch body width and through-hole mounting. Pin 7 is GND; Pin 14 is VCC; all inputs and outputs are arranged in mirrored pairs across the package centerline.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 4, 10, 13 | Output Enable (1OE, 2OE, 3OE, 4OE) | Active-high control: drives associated Y output to high-Z when low; enables buffer pass-through when high. |
| 2, 5, 9, 12 | Input (1A, 2A, 3A, 4A) | Non-inverting data input per channel; TTL-compatible thresholds ensure direct interfacing with legacy logic. |
| 3, 6, 8, 11 | Output (1Y, 2Y, 3Y, 4Y) | Buffered non-inverting output; capable of sinking 64 mA while holding VOL ≤ 0.42 V. |
| 7 | GND | Ground reference for all internal circuitry and output current return path. |
| 14 | VCC | Positive supply rail (4.5–5.5 V); powers BiCMOS output stage and input clamp protection network. |
Key Features
| Feature | Design Value |
|---|---|
| BiCMOS process technology | Reduces ICCZ to 5–10 mA in 3-state mode - cuts quiescent power by >50% versus equivalent bipolar-only buffers. |
| TTL-compatible input thresholds | VIL = 0.8 V / VIH = 2.0 V - enables seamless integration with legacy 74LS/74F logic without interface resistors or level shifters. |
| High-current 3-state outputs | Sinks up to 64 mA per output while maintaining VOL ≤ 0.42 V - supports fan-out to ≥20 standard TTL loads. |
| ESD protection | Exceeds 2000 V per MIL-STD-883C Method 3015 - enhances reliability during board handling and system integration. |
| Standard PDIP package | 14-pin N package with 0.3″ width - supports manual prototyping, socket-based testing, and legacy wave-solder assembly. |
Applications
| Memory Address Buffering | Legacy Bus Isolation |
|---|---|
|
Use Scenario: Isolating CPU address lines from multiple memory banks in industrial PLC backplanes. IC Role / Device Role / Timing Role: Non-inverting buffer with per-channel 3-state control synchronizes address latching and prevents bus contention during bank switching. Use Value: 1.5 ns tPLH min ensures address setup integrity across 10-MHz bus cycles; 64 mA drive sustains signal integrity over 6-inch routed traces. |
Use Scenario: Enabling/disabling peripheral modules (e.g., UART, ADC) on shared 8-bit data buses in test equipment. IC Role / Device Role / Timing Role: Quad 3-state gate provides independent enable control per peripheral, eliminating need for discrete gating logic. Use Value: IOZL ≤ –50 µA in high-Z state prevents leakage-induced logic glitches; VOL ≤ 0.42 V guarantees noise margin >0.8 V at 5-V rails. |
| Industrial Control Backplane | Embedded System Expansion Interface |
|
Use Scenario: Driving long-run parallel control signals (e.g., stepper motor enable, relay drivers) in factory automation racks. IC Role / Device Role / Timing Role: High-current buffer translates microcontroller GPIO to robust 64 mA outputs capable of driving optocouplers or small relays directly. Use Value: ICCZ = 5–10 mA allows continuous 3-state standby without thermal derating; BiCMOS design avoids latch-up under transient load spikes. |
Use Scenario: Interfacing FPGA I/O banks to legacy 5-V peripheral cards via mezzanine connectors in modular instrumentation. IC Role / Device Role / Timing Role: Level-tolerant buffer bridges modern FPGA core voltages to 5-V bus standards using only VCC = 5 V and no external level shifters. Use Value: VIH = 2.0 V and VIL = 0.8 V accept 3.3-V LVTTL outputs directly; tPHL = 2.7 ns max preserves timing margins in 25-MHz expansion cycles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus buffering applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS126N | Lower drive (IOL = 24 mA), higher ICCZ (30 mA), slower tPLH (15 ns typ), bipolar-only process. | Acceptable only for low-speed, low-fanout 5-V TTL systems where power and speed are not critical. | Choose SN74LS126N only if legacy stock exists and timing/power budgets allow 3× longer delays and 3× higher standby current. |
| SN74ACT126N | CMOS process, wider VCC range (4.5–5.5 V), lower VOL (0.35 V), faster tPLH (1.2 ns min), but lower IOL (24 mA). | Better for high-speed, low-noise digital interfaces; unsuitable for driving heavy TTL loads or relays requiring >24 mA. | Prefer SN74ACT126N for clock distribution or FPGA-to-FPGA links; retain SN74BCT126AN when driving mixed-logic buses or legacy peripherals needing 64 mA sink capability. |
Compared with SN74LS126N and SN74ACT126N, the SN74BCT126AN uniquely balances high current drive (64 mA), low ICCZ (5–10 mA), and sub-7-ns timing - making it the optimal choice for industrial backplanes and memory subsystems where both robustness and speed matter.
Availability
SN74BCT126AN is available at Aetrix Electronics and suitable for industrial control backplanes, legacy bus isolation, and memory address buffering requiring stable component supply across extended product lifecycles.
Supply support for SN74BCT126AN 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 for industrial, automotive, and communications markets.
The SN74BCT126AN belongs to TI's BCT-series BiCMOS logic family, engineered specifically to replace high-power 74S/74F buffers in 5-V systems while reducing power consumption and improving noise immunity.
FAQ
What is the operating temperature range for the SN74BCT126AN?
The SN74BCT126AN is characterized for operation from 0°C to 70°C - the commercial temperature grade. This distinguishes it from the military-grade SN54BCT126A (–55°C to 125°C). The SN74BCT126AN's thermal specification is validated per TI's SCBS252A datasheet and applies strictly to the N-package variant.
Does the SN74BCT126AN support 3.3-V input logic levels?
Yes - the SN74BCT126AN accepts 3.3-V logic-high inputs reliably because its VIH threshold is specified at 2.0 V min (with VCC = 4.5–5.5 V). A 3.3-V signal exceeds this by 1.3 V margin, ensuring robust recognition as a logic high without external pull-ups or level shifters.
What is the maximum capacitive load the SN74BCT126AN can drive while meeting timing specs?
The SN74BCT126AN's switching characteristics (tPLH, tPHL, tPZL, etc.) are guaranteed with CL = 50 pF, as defined in the SCBS252A datasheet. Driving loads beyond 50 pF increases propagation delay nonlinearly and may violate setup/hold timing in high-speed designs - use series termination or buffer staging for >100-pF nets.
Is the SN74BCT126AN RoHS compliant?
Yes - the SN74BCT126AN is marked Pb-Free (RoHS) with CU NIPDAU finish, as confirmed in TI's official Packaging Information table. It meets EU RoHS Directive 2011/65/EU requirements, containing ≤0.1% lead by weight in homogeneous materials.
Can the SN74BCT126AN be used in place of the SN74LS126N without redesign?
No - although pin-compatible, the SN74BCT126AN has different DC and AC behavior: higher output drive (64 mA vs. 24 mA), lower ICCZ (5–10 mA vs. ~30 mA), and faster timing (1.5 ns vs. 15 ns tPLH). Layout changes aren't needed, but timing analysis and power budget validation are required before substitution.
SN74BCT126AN Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74BCT
- Package/Case:
- 14-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Discontinued at Digi-Key
- Logic Type:
- Buffer, Non-Inverting
- Number of Elements:
- 4
- Number of Bits per Element:
- 1
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 15mA, 64mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 14-PDIP
SN74BCT126AN FAQ
1.How can I place an order for SN74BCT126AN through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74BCT126AN 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 SN74BCT126AN reliable?
The price and inventory of SN74BCT126AN are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT126AN is usually 5 days.
3.What payment methods are accepted for SN74BCT126AN?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74BCT126AN transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74BCT126AN?
SN74BCT126AN orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74BCT126AN 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 SN74BCT126AN?
For technical support, including SN74BCT126AN datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT126AN requirements.
6.How does Aetrix verify that SN74BCT126AN is sourced from the original manufacturer or authorized distributors?
All SN74BCT126AN 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 SN74BCT126AN meets industry standards.
7.What is the process for return or replacement of SN74BCT126AN?
All SN74BCT126AN units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT126AN, 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 SN74BCT126AN part is unused and in its original packaging.
Return procedure for SN74BCT126AN:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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