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Texas Instruments SN74HC126N
- Part No.:
- SN74HC126N
- Manufacturer:
- Texas Instruments
- Package:
- 14-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74HC126N.pdf
- Description:
- IC BUFFER NON-INVERT 6V 14DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,990
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Product details
Overview
SN74HC126N from Texas Instruments is a quadruple 3-state buffer IC used for digital signal enabling and bus isolation in TTL- and CMOS-compatible systems. It operates across 2 V–6 V supply, supports –40°C to +85°C ambient, delivers ≤31 ns propagation delay at 6 V, and drives up to 10 LSTTL loads. It is commonly deployed in 4-bit data bus control where independent channel enable/disable is required.
For engineers reviewing the SN74HC126N datasheet, SN74HC126N pinout, SN74HC126N application, or SN74HC126N equivalent, key selection considerations include its 14-pin PDIP package, per-channel 3-state output control, CMOS input compatibility, and guaranteed performance over industrial temperature range without derating.
Technical Context
The SN74HC126N implements four independent non-inverting buffers, each with dedicated active-low output-enable (OE) control and Boolean function Y = A. Its balanced CMOS 3-state outputs support bidirectional current sourcing/sinking up to ±35 mA per pin while maintaining high-impedance states with ≤±0.5 µA leakage at 6 V.
It uses standard CMOS inputs with ≤10 pF capacitance and requires input transition times ≤400 ns at 6 V to prevent shoot-through current. The device complies with HCMOS logic levels and interfaces directly with LSTTL, HC, HCT, and AC families without level-shifting.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2 V to 6 V - enables direct interface with 3.3 V and 5 V logic domains without external regulators |
| Operating Temperature | –40°C to +85°C - qualified for industrial-grade embedded control and instrumentation applications |
| Propagation Delay | 11 ns (typ) at 6 V, CL = 50 pF - ensures timing integrity in 30+ MHz bus enable/disable cycles |
| Output Drive | ±6 mA at VOH/VOL = 3.98 V/0.26 V (4.5 V VCC) - sufficient to drive 10 LSTTL loads or fan out to multiple CMOS inputs |
| 3-State Leakage | ±0.5 µA max at 6 V - minimizes unintended loading during high-Z state in shared-bus architectures |
| Input Capacitance | 10 pF max - reduces capacitive loading on upstream drivers and preserves signal edge rates |
| Power Dissipation Cap. | 45 pF per gate - enables accurate dynamic power estimation using CMOS switching equations |
Pinout & Package
SN74HC126N is housed in a 14-pin plastic dual in-line package (PDIP) with 19.30 mm × 6.40 mm body size and through-hole mounting. Pin 1 is top-left corner when notch faces upward.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 4, 10, 13 | Channel OE (active-low) | Independent 3-state enable control per buffer; low = output active, high = high-Z |
| 2, 5, 9, 12 | Channel A (input) | Non-inverting data input; CMOS-compatible threshold, ≤10 pF load |
| 3, 6, 8, 11 | Channel Y (output) | Buffered, 3-state output; sinks/sources ±35 mA, high-Z leakage ≤0.5 µA |
| 7 | GND | Logic ground reference and primary return path for all output sink currents |
| 14 | VCC | Positive supply rail; must be bypassed with 0.1 µF ceramic capacitor near pin |
Key Features
| Feature | Design Value |
|---|---|
| Quadruple independent buffers | Four isolated channels allow concurrent or staggered bus enable control without crosstalk |
| Wide supply voltage range | 2 V–6 V operation eliminates need for separate voltage rails in mixed-supply systems |
| Industrial temperature rating | –40°C to +85°C guarantee ensures reliability in uncontrolled environments like factory automation |
| Balanced 3-state outputs | Symmetric drive strength (±6 mA) simplifies PCB trace design and termination for bidirectional buses |
| Low dynamic power | ICC ≤ 80 µA at 6 V enables use in low-power wake-up or standby signal routing paths |
Applications
| Microcontroller I/O Expansion | Legacy Bus Interface |
|---|---|
Use Scenario: Expanding GPIO count of an MCU by connecting parallel peripherals (e.g., ADCs, DACs, sensors) to a shared data bus. IC Role / Device Role / Timing Role: SN74HC126N acts as a controllable buffer between MCU port pins and peripheral data lines, isolating inactive devices. Use Value: Enables software-selectable peripheral access without hardware contention; leverages active-low OE for direct GPIO control. | Use Scenario: Interfacing modern microcontrollers with legacy 8-bit parallel peripherals (e.g., EPROMs, LCD controllers) requiring 3-state bus drivers. IC Role / Device Role / Timing Role: SN74HC126N provides level-compatible buffering and bus arbitration between mismatched logic families. Use Value: Eliminates need for discrete pull-ups or level shifters; supports clean bus release via high-Z state during idle cycles. |
| Test Equipment Signal Gating | Industrial Control Backplane |
Use Scenario: Enabling/disabling test signals in automated test equipment (ATE) to route stimulus or capture responses without short-circuit risk. IC Role / Device Role / Timing Role: SN74HC126N serves as a digitally controlled gate for analog/digital test paths, synchronized to system clock edges. Use Value: Prevents signal injection into powered-down DUT sections; high-Z state avoids loading sensitive measurement nodes. | Use Scenario: Isolating modular I/O cards on a shared backplane in PLC or motion controller chassis. IC Role / Device Role / Timing Role: SN74HC126N buffers card-local address/data lines to the main backplane bus, with OE tied to slot-select logic. Use Value: Supports hot-swap-safe bus arbitration; prevents fault propagation between modules during insertion/removal. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 3-state buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT126N | TTL-compatible input thresholds (VIH = 2.0 V min), identical pinout and 3-state behavior | Better suited for mixed 5 V TTL/HCMOS systems where input noise margin is critical | Select when interfacing with legacy 5 V TTL outputs; otherwise SN74HC126N offers wider VCC flexibility |
| 74LCX126N | Lower VCC range (2.0 V–3.6 V), higher speed (tpd = 5.5 ns typ @ 3.3 V), same PDIP-14 footprint | Optimized for 3.3 V-only systems with tighter timing budgets and lower power | Choose for 3.3 V designs requiring sub-6 ns delay; not suitable for 5 V operation or mixed-voltage buses |
Compared with SN74HCT126N and 74LCX126N, the SN74HC126N uniquely balances broad supply voltage support (2–6 V), industrial temperature range, and proven robustness in mixed-logic bus isolation-making it the default choice for general-purpose 3-state buffering where voltage flexibility and reliability outweigh marginal speed gains.
Availability
SN74HC126N is available at Aetrix Electronics and suitable for industrial control backplanes, test equipment signal gating, microcontroller I/O expansion, and legacy bus interface applications requiring stable component supply across extended product lifecycles.
Supply support for SN74HC126N 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 delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74HC126N belongs to TI's 74HC logic family, designed specifically for robust, low-power, voltage-flexible digital interfacing in industrial and commercial systems where reliability and long-term availability are essential.
FAQ
What is the maximum capacitive load the SN74HC126N can drive while meeting datasheet timing specs?
The SN74HC126N is characterized for CL ≤ 50 pF in switching specifications, with propagation delay up to 31 ns at 6 V. Driving >70 pF may increase tpd beyond spec limits and cause ringing; TI recommends adding a series resistor if larger loads are unavoidable. The SN74HC126N datasheet specifies CL = 50 pF and CL = 150 pF test conditions to clarify performance boundaries under varying loads.
Can the SN74HC126N operate reliably at 3.3 V supply voltage?
Yes, the SN74HC126N is fully specified from 2 V to 6 V, including 3.3 V. At 3.3 V, it delivers VOH ≥ 3.15 V and VOL ≤ 0.33 V under 6 mA load, meets VIH/VIL thresholds for 3.3 V CMOS, and achieves ~18 ns typical propagation delay. All electrical and switching characteristics in the SN74HC126N datasheet apply across this full range.
How should unused inputs and outputs be handled on the SN74HC126N?
Unused inputs must be terminated to VCC or GND (not left floating) to prevent oscillation and excess current draw; 10 kΩ pull-up/down resistors are recommended. Unused outputs may be left unconnected (floating) since the SN74HC126N has no internal clamps that require termination. This guidance is explicitly stated in the SN74HC126N datasheet Section 9.2.1.2 and Figure 11-1 layout example.
Does the SN74HC126N support hot-swap or live-insertion on a powered bus?
No, the SN74HC126N does not include hot-swap protection circuitry. Its absolute maximum ratings specify that VCC must be powered before applying input signals, and IOZ leakage (≤0.5 µA) is only guaranteed when VCC is present. Inserting the SN74HC126N into a live 5 V bus risks violating VI or VO limits and damaging inputs/outputs per Section 6.1 of the SN74HC126N datasheet.
What is the thermal resistance (RθJA) of the SN74HC126N in its PDIP package?
The SN74HC126N in PDIP (N) package has a junction-to-ambient thermal resistance (RθJA) of 62.5°C/W, as published in Table 6.3 of the official SN74HC126N datasheet. This value assumes standard JEDEC 2S2P board conditions and confirms suitability for natural-convection cooling in industrial enclosures without forced airflow or heatsinks.
SN74HC126N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 14-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- Product Status:
- Active
- 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:
- 7.8mA, 7.8mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 14-PDIP
SN74HC126N FAQ
1.How can I place an order for SN74HC126N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC126N 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 SN74HC126N reliable?
The price and inventory of SN74HC126N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC126N is usually 5 days.
3.What payment methods are accepted for SN74HC126N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC126N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC126N?
SN74HC126N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC126N 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 SN74HC126N?
For technical support, including SN74HC126N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC126N requirements.
6.How does Aetrix verify that SN74HC126N is sourced from the original manufacturer or authorized distributors?
All SN74HC126N 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 SN74HC126N meets industry standards.
7.What is the process for return or replacement of SN74HC126N?
All SN74HC126N units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC126N, 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 SN74HC126N part is unused and in its original packaging.
Return procedure for SN74HC126N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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