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Texas Instruments CD74HCT126E
- Part No.:
- CD74HCT126E
- Manufacturer:
- Texas Instruments
- Package:
- 14-DIP (0.300", 7.62mm)
- Datasheet:
-
CD74HCT126E.pdf
- Description:
- IC BUF NON-INVERT 5.5V 14DIP
- Quantity:
- Payment:
- Shipping:
Inventory:129
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Product details
Overview
CD74HCT126E from Texas Instruments is a quadruple non-inverting buffer with 3-state outputs, designed for bus interface and signal enable applications in digital logic systems. It operates across 2 V to 6 V supply voltage, supports –55°C to +125°C temperature range, delivers propagation delay as low as 17 ns at 6 V, and drives up to 10 LSTTL loads. It is commonly used to isolate or enable bidirectional data paths in microcontroller peripheral interfaces.
For engineers reviewing the CD74HCT126E datasheet, CD74HCT126E pinout, CD74HCT126E application, or CD74HCT126E equivalent, key selection criteria include its 3-state output control per channel, CMOS-compatible input thresholds, rail-to-rail output swing, and PDIP-14 package suitability for prototyping and legacy industrial PCBs.
Technical Context
This device implements four independent positive-logic buffers (Y = A), each with dedicated active-low output-enable (OE) control. Its 3-state outputs allow dynamic bus sharing without contention, while balanced CMOS drive ensures symmetrical sourcing/sinking capability up to ±7.8 mA per output at 6 V.
The CD74HCT126E uses standard CMOS inputs with VIH/VIL thresholds scaled to VCC (e.g., VIH = 3.15 V at VCC = 4.5 V), enabling direct interfacing with TTL and mixed-voltage logic families. Input transition time limits (≤400 ns at 6 V) prevent shoot-through current and oscillation during slow-edge transitions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 2 V to 6 V - enables interoperability with 3.3 V and 5 V logic domains without level shifters |
| Operating Temperature | –55°C to +125°C - qualified for extended industrial and automotive under-hood environments |
| Propagation Delay | 17 ns max at 6 V, CL = 50 pF - supports reliable operation in 20 MHz+ digital control loops |
| Output Drive | ±7.8 mA at 6 V - sufficient to drive 10 LSTTL loads or moderate capacitive buses (≤70 pF) |
| Input Leakage | ±1 µA max at 6 V - negligible loading on high-impedance sources such as microcontroller GPIOs |
| Three-State Leakage | ±10 µA max at 6 V - ensures stable high-impedance state during bus arbitration |
| Power Dissipation Cap. | 30 pF per gate - used to calculate dynamic power consumption in clocked applications |
Pinout & Package
CD74HCT126E is housed in a 14-pin Plastic Dual In-line Package (PDIP) with nominal body size 19.30 mm × 6.40 mm, through-hole mounting, and RoHS-compliant NiPdAu lead finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 2OE, 3OE, 4OE | Active-low output enable (per channel) | Drives corresponding Y output to high-impedance when logic HIGH; enables buffer pass-through when logic LOW |
| 1A, 2A, 3A, 4A | Buffer input (per channel) | Accepts CMOS/TTL-compatible logic signals; high-impedance input draws <1 µA |
| 1Y, 2Y, 3Y, 4Y | Buffered 3-state output (per channel) | Replicates input A when OE is active; enters high-Z state otherwise - prevents bus contention |
| VCC (Pin 14) | Positive supply | Provides operating voltage for all four channels; requires local 0.1 µF bypass capacitor |
| GND (Pin 7) | Ground reference | Common return path for all I/O and supply currents; must be low-impedance for noise immunity |
Key Features
| Feature | Design Value |
|---|---|
| Quadruple 3-state buffer architecture | Enables independent control of four signal paths - ideal for 4-bit data bus isolation or parallel peripheral enable |
| Rail-to-rail output swing | VOH ≥ 5.48 V and VOL ≤ 0.4 V at 6 V/7.8 mA - ensures robust noise margins against TTL and CMOS receivers |
| Wide supply voltage range | Operates from 2 V to 6 V - supports mixed-voltage system design and brown-out tolerant operation |
| Low quiescent current | ICC ≤ 160 µA at 6 V - minimizes static power in always-on control logic |
| ESD protection | ±2000 V HBM - meets industrial handling requirements without external protection circuitry |
Applications
| Microcontroller Bus Interface | Industrial Sensor Data Multiplexing |
|---|---|
Use Scenario: Isolating an 8-bit parallel sensor array from a microcontroller's GPIO port during firmware updates. IC Role / Device Role: Four CD74HCT126E channels enable/disable two 4-bit data lanes between sensors and MCU, preventing spurious writes. Use Value: Eliminates need for software-controlled tri-state management; hardware-level bus isolation reduces firmware complexity and timing-critical code paths. | Use Scenario: Sharing a single ADC input line among four analog sensors using discrete switching. IC Role / Device Role: Each buffer channel acts as a digitally controlled analog switch - enabled only when its sensor is active. Use Value: Prevents crosstalk and loading effects between sensors; avoids analog multiplexer IC cost and channel count limitations. |
| Legacy System Signal Conditioning | Test Equipment Digital I/O Expansion |
Use Scenario: Adapting modern 3.3 V FPGA outputs to legacy 5 V TTL logic in avionics maintenance testers. IC Role / Device Role: Buffers translate voltage levels while providing fanout gain and 3-state control for shared backplane lines. Use Value: Enables drop-in replacement of obsolete 74LS126 without redesigning PCB layout or adding discrete level shifters. | Use Scenario: Expanding digital stimulus/response capability of benchtop test equipment with user-configurable I/O banks. IC Role / Device Role: Multiple CD74HCT126E devices provide programmable enable/disable of grouped DUT signals during automated test sequences. Use Value: Supports reconfigurable test fixtures via simple GPIO control - no FPGA or CPLD required for basic signal gating. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buffer-with-3-state-output applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT125N | Quad buffer with active-high OE (vs. active-low OE in CD74HCT126E); identical timing, drive, and voltage specs | Requires inverted OE control logic; unsuitable where existing firmware assumes active-low enable | Select when system-level OE signals are active-HIGH and board layout allows OE signal inversion |
| CD74HC126E | Same pinout and function but HC (not HCT) family - VIH/VIL thresholds scale with VCC, not fixed TTL levels | Less compatible with 5 V TTL inputs; may misread marginal 3.3 V logic HIGH in mixed-signal systems | Prefer for pure CMOS systems or where lower ICC (<80 µA) and wider VCC tolerance (2–6 V) outweigh TTL compatibility needs |
Compared with SN74HCT125N and CD74HC126E, the CD74HCT126E provides guaranteed TTL-input compatibility at 5 V while retaining CMOS power efficiency - making it optimal for bridging legacy and modern logic domains without signal integrity compromise.
Availability
CD74HCT126E is available at Aetrix Electronics and suitable for industrial control panels, aerospace test instrumentation, and automotive diagnostic tools requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for CD74HCT126E 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 connectivity solutions for industrial, automotive, and consumer applications.
The CD74HCT126E belongs to TI's 74HCT logic family, engineered specifically to combine TTL-compatible input thresholds with CMOS power efficiency - targeting mixed-voltage digital interface and bus isolation use cases.
FAQ
What is the maximum capacitive load the CD74HCT126E can drive while maintaining specified timing?
The CD74HCT126E is characterized for CL = 50 pF in switching specifications, with typical performance verified up to 70 pF. Driving loads beyond 70 pF increases propagation delay and transition time nonlinearly and may violate setup/hold timing in synchronous systems. For loads >70 pF, add a series resistor to limit peak output current per Section 6.1 absolute maximum ratings.
Can the CD74HCT126E operate reliably at 3.3 V supply voltage?
Yes, the CD74HCT126E is fully specified from 2 V to 6 V, including 3.3 V. At 3.3 V, VIH = 2.0 V min and VIL = 0.8 V max ensure compatibility with 3.3 V CMOS outputs, while VOH ≥ 3.15 V and VOL ≤ 0.36 V maintain adequate noise margins. Propagation delay increases to ~25 ns (typical) at 3.3 V/50 pF.
How should unused inputs and outputs be handled on the CD74HCT126E?
Unused inputs must be terminated to VCC or GND - floating CMOS inputs cause excessive current draw and potential oscillation. Unused outputs may be left unconnected (floating) since the 3-state architecture isolates them when disabled. Do not tie outputs directly to VCC or GND, as this violates absolute maximum ratings during active output states.
Does the CD74HCT126E support hot insertion or live insertion into a powered backplane?
No, the CD74HCT126E lacks explicit hot-swap protection features such as power-up sequencing control, Ioff partial-power-down mode, or back-drive immunity. Applying VCC before GND or enabling outputs before supply stabilization risks latch-up or ESD damage. Use external current-limiting resistors and controlled power sequencing for backplane applications.
What is the thermal resistance (RθJA) of the CD74HCT126E in its PDIP package?
The CD74HCT126E in PDIP (N) package has RθJA = 62.2°C/W, measured per JEDEC JESD51 standards. This value assumes a standard 2-layer PCB with 1 in² copper pour under the package. Actual junction temperature rise depends on airflow, board copper area, and adjacent heat sources - derate power dissipation accordingly for operation above 70°C ambient.
CD74HCT126E Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 14-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- 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:
- 6mA, 6mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 14-PDIP
CD74HCT126E FAQ
1.How can I place an order for CD74HCT126E through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HCT126E 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 CD74HCT126E reliable?
The price and inventory of CD74HCT126E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HCT126E is usually 5 days.
3.What payment methods are accepted for CD74HCT126E?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HCT126E transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HCT126E?
CD74HCT126E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HCT126E 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 CD74HCT126E?
For technical support, including CD74HCT126E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HCT126E requirements.
6.How does Aetrix verify that CD74HCT126E is sourced from the original manufacturer or authorized distributors?
All CD74HCT126E 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 CD74HCT126E meets industry standards.
7.What is the process for return or replacement of CD74HCT126E?
All CD74HCT126E units undergo pre-shipment inspection (PSI). If there is an issue with CD74HCT126E, 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 CD74HCT126E part is unused and in its original packaging.
Return procedure for CD74HCT126E:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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