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Texas Instruments SN74AHCT126D
- Part No.:
- SN74AHCT126D
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74AHCT126D.pdf
- Description:
- IC BUF NON-INVERT 5.5V 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,222
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Product details
Overview
SN74AHCT126D from Texas Instruments is a quadruple bus buffer gate with independent 3-state outputs, designed for bidirectional bus interfacing in 5-V digital systems. It features TTL-compatible inputs (VIH = 2 V, VIL = 0.8 V), ±8 mA output drive at VCC = 4.5–5.5 V, and propagation delays as low as 1 ns (tPLH/tPHL) under 15-pF load - enabling reliable signal buffering in PC motherboard I/O expansion and server memory subsystems.
For engineers reviewing the SN74AHCT126D datasheet, SN74AHCT126D pinout, SN74AHCT126D application, or SN74AHCT126D equivalent, key selection criteria include its 3-state output control per channel, latch-up immunity (>250 mA), ESD robustness (2000-V HBM), and compatibility with mixed-voltage translation (e.g., 3.3-V logic driving 5-V buses).
Technical Context
The SN74AHCT126D implements four independent noninverting buffers, each with dedicated output-enable (OE) input controlling high-impedance state. Its CMOS design uses lowered TTL-compatible thresholds to support up-translation from 3.3-V logic while maintaining 5-V rail operation.
Each buffer operates with rail-to-rail output swing (VOH ≥ 3.8 V, VOL ≤ 0.44 V at IOL/IOH = ±8 mA), defined switching characteristics (tPLH/tPHL ≤ 7 ns at CL = 15 pF), and thermal performance characterized by RθJA = 124.5°C/W in SOIC-14 package - critical for thermally constrained board layouts in networking and embedded compute.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - ensures stable operation across industrial-grade 5-V supply tolerances |
| VIH / VIL | 2.0 V / 0.8 V - enables direct interface with legacy TTL and 3.3-V CMOS logic without level shifters |
| IOH / IOL | –8 mA / +8 mA - sufficient drive for fan-out of 10 LSTTL loads or termination into 50-Ω traces |
| tPLH / tPHL | 1 ns (min) to 7 ns (max) at CL = 15 pF - supports >100-MHz bus toggling with controlled edge rates |
| ICC (Quiescent) | 2 µA typical - negligible standby power in always-on system management functions |
| ESD HBM | 2000 V - meets IEC 61000-4-2 Level 2 for handling robustness in manufacturing and field service |
| Operating Temp | –40°C to +85°C - qualified for commercial-grade industrial control and computing applications |
Pinout & Package
SN74AHCT126D is housed in a 14-pin SOIC (Small Outline Integrated Circuit) package with standard 1.27-mm pitch, 8.65-mm body width, and JEDEC MS-012AC footprint - compatible with automated SMT placement and reflow profiles per IPC-J-STD-020.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 4, 10, 13 | Output Enable (1OE–4OE) | Active-high control per buffer; drives Y high-impedance when low - enables dynamic bus arbitration |
| 2, 5, 9, 12 | Data Input (1A–4A) | TTL-compatible input accepting 0–5.5 V; internally clamped to prevent overvoltage damage |
| 3, 6, 8, 11 | Data Output (1Y–4Y) | 3-state CMOS output with rail-swing capability; sinks/sours ±8 mA with defined VOL/VOH |
| 7 | GND | Reference return for all logic and power paths; must be low-impedance connection to minimize ground bounce |
| 14 | VCC | 5-V supply input; requires local 0.1-µF ceramic bypass capacitor placed within 3 mm of pin |
Key Features
| Feature | Design Value |
|---|---|
| TTL-voltage compatible inputs | Supports direct connection to 3.3-V microcontrollers and 5-V legacy peripherals without external level shifters |
| Independent 3-state control per channel | Enables selective bus isolation - e.g., disable only memory address lines while keeping data lines active |
| Latch-up immunity >250 mA | Guarantees robustness against transient current surges during hot-plug or ESD events per JESD17 |
| Slow edge rate (Δt/Δv = 20 ns/V) | Reduces output ringing and EMI in unterminated transmission lines, improving signal integrity on FR4 PCBs |
| Overvoltage-tolerant inputs | Accepts input voltages up to 5.5 V regardless of VCC value - simplifies mixed-supply system bring-up |
Applications
| PC Motherboard I/O Expansion | Server Memory Subsystem Buffering |
|---|---|
Use Scenario: Isolating PCI Express configuration registers from chipset reset sequences while maintaining hot-plug detection signaling. IC Role / Device Role / Timing Role: Bidirectional bus buffer with per-lane OE control, providing glitch-free register access during power sequencing. Use Value: Prevents spurious writes during reset by placing registers in high-Z state until initialization completes - eliminating firmware workarounds. | Use Scenario: Driving DDR3/DDR4 address and command buses from a 3.3-V memory controller to 5-V DIMM slot logic. IC Role / Device Role / Timing Role: Voltage-translating buffer with matched propagation delay across all four channels. Use Value: Enables clean 5-V logic-level signaling without timing skew between A0–A15 and BA0–BA2 lines - preserving setup/hold margins. |
| Industrial PLC Backplane Interface | Network Switch Control Plane Bus |
Use Scenario: Interfacing isolated CAN transceiver status signals to a 5-V FPGA-based backplane controller. IC Role / Device Role / Timing Role: Signal conditioner and voltage translator for fault-reporting lines with ESD protection. Use Value: Absorbs 2000-V HBM transients from field wiring while translating 3.3-V transceiver alerts to 5-V FPGA inputs - reducing external protection components. | Use Scenario: Buffering MDIO/MDC management bus between 3.3-V PHYs and 5-V switch fabric ASIC. IC Role / Device Role / Timing Role: Low-skew repeater ensuring deterministic read/write timing across multi-drop MDIO topology. Use Value: Maintains <1 ns inter-channel skew across all four buffered lines - meeting IEEE 802.3 clause 22 timing compliance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AHCT125D | Inverting output logic (A → Y̅); identical pinout, timing, and drive strength | Required where bus inversion is part of protocol (e.g., differential enable signaling) | Select when functional inversion is needed; otherwise, SN74AHCT126D provides direct logic mapping |
| SN74LVC126APW | 3.3-V only supply (1.65–3.6 V); lower drive (±24 mA), smaller TSSOP-14 package | Suitable for 3.3-V-only systems; not interoperable with 5-V buses | Choose for compact, low-power 3.3-V designs; avoid if 5-V compatibility or TTL input support is required |
Compared with SN74AHCT125D and SN74LVC126APW, the SN74AHCT126D uniquely combines 5-V operation, TTL input compatibility, and noninverting logic - making it irreplaceable in legacy 5-V infrastructure upgrades and mixed-voltage bus arbitration where signal polarity preservation is mandatory.
Availability
SN74AHCT126D is available at Aetrix Electronics and suitable for PC motherboard I/O expansion, server memory subsystem buffering, and industrial PLC backplane interface requiring stable component supply across extended product lifecycles.
Supply support for SN74AHCT126D 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 computing markets.
The SN74AHCT126D belongs to TI's AHCT logic family - engineered for seamless integration between 3.3-V and 5-V systems, emphasizing voltage translation, ESD resilience, and bus contention avoidance in high-density digital interfaces.
FAQ
What is the maximum operating temperature for the SN74AHCT126D?
The SN74AHCT126D is rated for operation from –40°C to +85°C, conforming to commercial-grade temperature specifications. This range supports deployment in desktop PCs, network switches, and industrial controllers where ambient temperatures remain within standard office or controlled-environment limits. The SOIC package's thermal resistance (RθJA = 124.5°C/W) ensures safe junction temperatures under typical board-level power dissipation.
Does the SN74AHCT126D support 3.3-V input logic levels?
Yes, the SN74AHCT126D accepts 3.3-V logic inputs reliably due to its TTL-compatible input thresholds: VIH = 2.0 V (minimum) and VIL = 0.8 V (maximum). This allows direct interfacing with 3.3-V microcontrollers and FPGAs while powered from a 5-V rail - enabling voltage up-translation without external level shifters. Inputs also tolerate up to 5.5 V regardless of VCC.
Can the SN74AHCT126D drive a 50-Ω transmission line?
The SN74AHCT126D can drive a 50-Ω line under specific conditions: its ±8 mA output current supports termination into 50 Ω at VOH ≈ 3.8 V and VOL ≈ 0.44 V (VCC = 4.5 V), yielding ~100-mA peak drive capability. However, for clean signal integrity, use series source termination or controlled-edge routing - the device's 20 ns/V input transition rate inherently limits ringing in such configurations.
Is the SN74AHCT126D pin-compatible with other AHCT-series buffers?
Yes, the SN74AHCT126D shares identical pinout and footprint with SN74AHCT125D (inverting), SN74AHCT244D (octal), and SN74AHCT541D (octal inverting) in SOIC-14 packages. This enables drop-in substitution where logic function matches, simplifying board reuse across buffer-intensive designs like memory controllers and I/O expanders.
What is the recommended bypass capacitor for the SN74AHCT126D VCC pin?
Texas Instruments recommends a 0.1-µF ceramic capacitor placed within 3 mm of the SN74AHCT126D VCC pin (pin 14) to suppress high-frequency noise and stabilize the 5-V supply during output switching. For boards with multiple SN74AHCT126D devices, add bulk capacitance (e.g., 1-µF tantalum) near the power entry point - but keep the 0.1-µF cap local to each IC to maintain low-inductance decoupling.
SN74AHCT126D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- 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:
- 8mA, 8mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SOIC
SN74AHCT126D FAQ
1.How can I place an order for SN74AHCT126D through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT126D 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 SN74AHCT126D reliable?
The price and inventory of SN74AHCT126D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT126D is usually 5 days.
3.What payment methods are accepted for SN74AHCT126D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT126D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHCT126D?
SN74AHCT126D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT126D 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 SN74AHCT126D?
For technical support, including SN74AHCT126D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT126D requirements.
6.How does Aetrix verify that SN74AHCT126D is sourced from the original manufacturer or authorized distributors?
All SN74AHCT126D 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 SN74AHCT126D meets industry standards.
7.What is the process for return or replacement of SN74AHCT126D?
All SN74AHCT126D units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT126D, 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 SN74AHCT126D part is unused and in its original packaging.
Return procedure for SN74AHCT126D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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