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Texas Instruments SN74AHCT126DG4
- Part No.:
- SN74AHCT126DG4
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74AHCT126DG4.pdf
- Description:
- IC BUF NON-INVERT 5.5V 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,928
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Product details
Overview
SN74AHCT126DG4 from Texas Instruments is a quadruple bus buffer gate with independent 3-state outputs, designed for bidirectional data bus isolation and level translation between 3.3-V and 5-V logic domains. It features TTL-compatible inputs (VIH = 2 V, VIL = 0.8 V), ±8-mA output drive at 5 V, and propagation delays as low as 1 ns (typical) under 15-pF load. It is widely deployed in PC motherboard I/O buffering and server memory subsystems.
For engineers reviewing the SN74AHCT126DG4 datasheet, SN74AHCT126DG4 pinout, SN74AHCT126DG4 application, or SN74AHCT126DG4 equivalent, key selection criteria include its 3-state control per channel, latch-up immunity (>250 mA), ESD robustness (2000-V HBM), and compatibility with legacy TTL input thresholds in mixed-voltage digital systems.
Technical Context
The SN74AHCT126DG4 implements four independent noninverting buffers, each with dedicated output-enable (OE) control. Each channel operates as a voltage-level translator: accepts 3.3-V CMOS or TTL inputs and drives 5-V CMOS loads while maintaining noise margins - enabled by lowered VIH/VIL thresholds and slow-edge design to suppress ringing.
Its 3-state outputs are actively disabled when OE is low, presenting high-impedance (IOZ ≤ ±2.5 µA) to prevent bus contention. The device uses standard CMOS process with Schmitt-trigger–free inputs and balanced rise/fall times, supporting reliable operation across –40°C to 125°C with supply voltage from 4.5 V to 5.5 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage (VCC) | 4.5 V to 5.5 V - ensures compatibility with regulated 5-V rails and tolerance against ripple or droop in industrial/server power supplies. |
| Input Thresholds | VIH = 2.0 V, VIL = 0.8 V - enables direct interfacing with 3.3-V TTL/CMOS outputs without level shifters. |
| Output Drive | ±8 mA at VOH/VOL - sufficient to drive multiple 5-V CMOS inputs (fan-out ≥ 10) while limiting ground bounce. |
| Propagation Delay | tPLH/tPHL = 1 ns (min), 7 ns (max) @ CL = 15 pF - supports >100-MHz bus toggle rates in short-trace applications. |
| ESD Rating | 2000-V HBM - meets IEC 61000-4-2 system-level robustness requirements for board-level handling and integration. |
| Operating Temperature | –40°C to 125°C - qualified for extended-temperature industrial and telecom infrastructure use cases. |
| Power Dissipation | Cpd = 14 pF - enables low dynamic power consumption (<1 mW @ 1 MHz, no load), critical for thermally constrained PCB layouts. |
Pinout & Package
SN74AHCT126DG4 is packaged in a 14-pin SOIC (D) package with 1.27-mm pitch, 8.65-mm body width, and surface-mount footprint compatible with IPC-7351B standards. Thermal resistance RθJA = 124.5°C/W (JEDEC std.) supports natural convection cooling in dense board layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 4, 10, 13 | Output Enable (1OE–4OE) | Active-high control per channel; low = high-Z output, prevents bus contention during power sequencing. |
| 2, 5, 9, 12 | Data Input (1A–4A) | TTL-compatible inputs accepting 0–5.5 V; overvoltage tolerant up to 5.5 V regardless of VCC. |
| 3, 6, 8, 11 | Data Output (1Y–4Y) | Noninverting buffered outputs; drive strength and voltage levels track VCC (4.4 V VOH min @ –8 mA). |
| 7 | GND | Ground reference for all I/O and internal logic; requires low-inductance connection to minimize switching noise. |
| 14 | VCC | 5-V supply pin; must be decoupled with 0.1-µF ceramic capacitor placed within 3 mm of the pin. |
Key Features
| Feature | Design Value |
|---|---|
| TTL-input compatibility | VIH = 2.0 V / VIL = 0.8 V enables seamless interface with legacy 3.3-V microcontrollers and FPGAs without external biasing. |
| Per-channel 3-state control | Four independent OE pins allow selective bus isolation - essential for multi-master arbitration in PCIe or SMBus peripheral hubs. |
| Slow-edge output design | Controlled slew rate minimizes overshoot/undershoot on unterminated traces, reducing EMI and signal integrity risk in compact PCBs. |
| Latch-up immunity | Exceeds 250 mA per JESD17 - eliminates risk of destructive latch-up during hot-swap or transient overvoltage events. |
| Wide temperature range | Rated for –40°C to 125°C operation - suitable for base station RF modules and automotive infotainment head units. |
Applications
| Server Memory Buffering | PC I/O Expansion Hub |
|---|---|
Use Scenario: Isolating DDR memory command/address buses from CPU-side logic to reduce capacitive loading and timing skew. IC Role / Device Role / Timing Role: Noninverting buffer with per-line 3-state control acts as timing-transparent repeater and contention guard. Use Value: Enables stable 1066-MT/s DDR3 operation by maintaining signal integrity across split-plane routing and reducing fan-out burden on memory controller. |
Use Scenario: Interfacing USB 2.0 hub controllers (3.3-V I/O) with legacy ISA or LPC bus peripherals (5-V logic). IC Role / Device Role / Timing Role: Level-translating bus buffer providing bidirectional voltage domain bridging with minimal propagation delay. Use Value: Eliminates need for discrete level-shifter ICs or resistor-divider networks, saving BOM cost and PCB area in space-constrained laptop daughterboards. |
| Industrial Network Switch Backplane | Wearable Health Sensor Aggregation |
Use Scenario: Driving parallel status/control lines between FPGA-based switch fabric and PHY management ICs across long PCB traces. IC Role / Device Role / Timing Role: Low-noise buffer mitigating crosstalk and ringing on 10-cm+ backplane traces operating at 25-MHz update rates. Use Value: Achieves <1% overshoot on 5-V signals without termination resistors, simplifying layout and improving EMC compliance in Class A equipment. |
Use Scenario: Consolidating analog sensor outputs (ECG, SpO₂) into a shared 5-V ADC interface while preserving 3.3-V MCU logic levels. IC Role / Device Role / Timing Role: Signal-conditioning buffer isolating sensitive analog front-end from digital switching noise on shared ground planes. Use Value: Reduces ADC quantization error by >3 LSB through improved PSRR and reduced digital coupling, meeting ISO 13485 clinical accuracy requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC126A | Lower VCC range (1.65–3.6 V); 3.3-V only; higher speed (tPD = 3.7 ns typ), but no TTL input compatibility. | Suitable for pure 3.3-V systems; cannot replace SN74AHCT126DG4 in 5-V or mixed-voltage designs. | Select when operating exclusively at 3.3 V and requiring lower power or faster timing - not for 5-V bus translation. |
| 74ACT126 | Same pinout and function, but higher drive (±24 mA), higher ICC (20 µA vs. 2 µA), and narrower temp range (–40°C to 85°C). | Better for driving heavier loads or longer traces, but less suitable for thermally constrained or low-power portable designs. | Choose for legacy 5-V systems needing stronger drive; avoid where thermal budget or quiescent current is critical. |
Compared with SN74LVC126A and 74ACT126, the SN74AHCT126DG4 uniquely balances TTL input compatibility, 5-V operation, low ICC, and extended temperature range - making it the optimal choice for industrial servers and telecom infrastructure where voltage translation and reliability coexist.
Availability
SN74AHCT126DG4 is available at Aetrix Electronics and suitable for server backplanes, PC I/O expansion, and industrial network switches requiring stable component supply across extended temperature and long product lifecycles.
Supply support for SN74AHCT126DG4 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 decades of heritage in industry-standard logic families.
The SN74AHCT126DG4 belongs to TI's AHCT logic series - engineered for robust 5-V mixed-signal interfacing, emphasizing TTL compatibility, ESD resilience, and wide-temperature reliability in mission-critical infrastructure.
FAQ
What is the maximum output current per channel for SN74AHCT126DG4?
The SN74AHCT126DG4 supports ±8 mA per output (IOL/IOH) at VCC = 4.5 V to 5.5 V, with absolute maximum continuous output current rated at ±25 mA. This allows safe driving of up to 10 standard 5-V CMOS inputs while maintaining VOL ≤ 0.44 V and VOH ≥ 3.8 V under load - critical for signal integrity in high-fanout bus applications.
Does SN74AHCT126DG4 support 3.3-V input logic levels?
Yes, SN74AHCT126DG4 explicitly supports 3.3-V TTL-compatible inputs: VIH = 2.0 V (min) and VIL = 0.8 V (max) ensure reliable recognition of 3.3-V logic highs and lows. Its inputs are overvoltage tolerant up to 5.5 V, enabling direct connection to 3.3-V microcontrollers without level-shifting circuitry - a core feature confirmed in TI's SCLS265S datasheet Section 5.3.
What is the operating temperature range of SN74AHCT126DG4?
The SN74AHCT126DG4 is rated for operation from –40°C to 125°C, as specified in the Recommended Operating Conditions table (Section 5.3). This extended range qualifies it for deployment in harsh environments such as telecom base stations, industrial PLCs, and automotive engine-control adjacent modules - exceeding the commercial-grade 0°C to 70°C typical of many logic buffers.
Is SN74AHCT126DG4 pin-compatible with other AHCT-series quad buffers?
Yes, SN74AHCT126DG4 shares identical pinout and function with SN74AHCT125 (inverting) and SN74AHCT126 variants across D, DB, PW, and NS packages. Pin mapping for 1A–4Y, 1OE–4OE, GND, and VCC is standardized per JEDEC MS-012, enabling drop-in replacement in existing SOIC-14 layouts - verified in TI's Pin Configuration and Functions (Figure 4-1 and Table 4-1).
How does SN74AHCT126DG4 handle power-up and power-down sequencing?
During power-up/down, SN74AHCT126DG4 outputs enter high-impedance state if OE is low; to ensure defined behavior, TI recommends tying each OE pin to GND via a pull-down resistor (value determined by driver strength). This prevents bus contention and floating states - a requirement detailed in Section 7.1 Overview and Application Section 8.2.1 of the SN74AHCT126DG4 datasheet.
SN74AHCT126DG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- 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
SN74AHCT126DG4 FAQ
1.How can I place an order for SN74AHCT126DG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT126DG4 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 SN74AHCT126DG4 reliable?
The price and inventory of SN74AHCT126DG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT126DG4 is usually 5 days.
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SN74AHCT126DG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT126DG4 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 SN74AHCT126DG4?
For technical support, including SN74AHCT126DG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT126DG4 requirements.
6.How does Aetrix verify that SN74AHCT126DG4 is sourced from the original manufacturer or authorized distributors?
All SN74AHCT126DG4 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 SN74AHCT126DG4 meets industry standards.
7.What is the process for return or replacement of SN74AHCT126DG4?
All SN74AHCT126DG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT126DG4, 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 SN74AHCT126DG4 part is unused and in its original packaging.
Return procedure for SN74AHCT126DG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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