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Texas Instruments SN74AHCT125N
- Part No.:
- SN74AHCT125N
- Manufacturer:
- Texas Instruments
- Package:
- 14-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74AHCT125N.pdf
- Description:
- IC BUF NON-INVERT 5.5V 14DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,800
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Product details
Overview
SN74AHCT125N from Texas Instruments is a quadruple bus buffer gate with independent 3-state outputs, designed for digital signal routing and isolation in 5-V logic systems. It features TTL-voltage-compatible inputs (VIH = 2 V, VIL = 0.8 V), ±8 mA output drive, 6.5 ns typical propagation delay (CL = 15 pF), and operates across –40°C to +85°C - used in microcontroller GPIO expansion, LED control, and switch debouncing circuits.
For engineers reviewing the SN74AHCT125N datasheet, SN74AHCT125N pinout, SN74AHCT125N application, or SN74AHCT125N equivalent, key selection criteria include its 14-pin PDIP package, individual OE-controlled 3-state outputs, 5-V supply compatibility, and robust noise immunity (VOL(P) = 0.8 V, VOH(V) = 4.4 V) in mixed-signal board interfaces.
Technical Context
The SN74AHCT125N implements four independent CMOS buffer gates, each with dedicated output-enable (OE) control enabling per-channel tri-state operation. Its TTL-compatible input thresholds allow direct interfacing with legacy 5-V TTL logic without level shifting.
Each gate passes A→Y when OE is low (active-low enable), and presents high-impedance output when OE is high. Power-up/down high-Z behavior requires OE tied to VCC via pullup resistor (value determined by driver sink capability), ensuring safe bus contention avoidance during sequencing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures stable operation across industrial 5-V rail tolerances |
| Output Drive | ±8 mA - sufficient to directly drive LEDs, small capacitive loads, or fan-out to multiple 74AHCT inputs |
| Propagation Delay | 1 ns to 6.5 ns (CL = 15 pF) - supports >100 MHz data rates in short-bus applications |
| Input Thresholds | VIH = 2 V, VIL = 0.8 V - guarantees interoperability with standard TTL logic families |
| Quiescent Current | ICC = 20 µA max - enables low-static-power operation in always-on control paths |
| Thermal Resistance | θJA = 80 °C/W (PDIP) - defines maximum power dissipation before thermal derating at ambient |
| ESD Rating | ≥250 mA latch-up immunity (JESD 17) - provides robustness against board-level transients |
Pinout & Package
SN74AHCT125N uses a 14-pin plastic dual in-line package (PDIP, N package), with 0.3-inch body width and through-hole mounting. Pin 1 is marked with a notch or dot; pin numbering follows standard DIP convention (counterclockwise from top-left).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 4, 10, 13 (OE1–OE4) | Active-low output enable | Individually disables corresponding buffer output to high-impedance state; tie to VCC for default disable |
| 2, 5, 9, 12 (A1–A4) | Buffer input | Accepts TTL-compatible logic signals; must be terminated to VCC or GND if unused |
| 3, 6, 8, 11 (Y1–Y4) | Buffer output | Drives downstream logic or loads; floats when OE is high; no external pullup required |
| 7 (GND) | Ground reference | Primary return path for all I/O and supply currents; must connect to system ground plane |
| 14 (VCC) | Power supply | 5-V nominal supply; requires local 0.1-µF bypass capacitor placed adjacent to pin |
Key Features
| Feature | Design Value |
|---|---|
| TTL-compatible inputs | Accepts 0.8 V / 2.0 V thresholds - eliminates need for external level translators when interfacing with legacy TTL |
| Independent 3-state control | Four separate OE pins enable selective bus isolation - critical for multi-master or shared-bus architectures |
| High-impedance on power-up | OE-high default state prevents bus contention during power sequencing - simplifies system reset design |
| Low quiescent current | 20 µA max ICC - reduces standby power in battery-backed or energy-sensitive control modules |
| Noise-immune switching | VOL(P) = 0.8 V, VOH(V) = 4.4 V - maintains ≥1.2 V noise margin under dynamic load conditions |
Applications
| Microcontroller GPIO Expansion | LED Indicator Control |
|---|---|
Use Scenario: Expanding limited MCU GPIO count to drive multiple peripherals without multiplexing delays. IC Role / Device Role / Timing Role: Bus buffer isolating MCU pins from peripheral loads while enabling/disabling signal paths per function. Use Value: Enables simultaneous control of up to four independent lines using single IC; avoids software overhead of bit-banged timing. |
Use Scenario: Driving discrete status LEDs from low-drive-capability MCU outputs. IC Role / Device Role / Timing Role: Level-shifting and current-boosting buffer between MCU GPIO and LED anode/cathode. Use Value: Delivers ±8 mA per channel - sufficient for bright visible-light LEDs without external transistors. |
| Pushbutton Switch Debouncing | Digital Signal Enable/Disable |
Use Scenario: Cleaning mechanical switch bounce in user-interface panels or industrial controls. IC Role / Device Role / Timing Role: Input conditioning gate with controlled propagation delay filtering rapid transitions. Use Value: 6.5 ns typical tPLH/tPHL ensures clean edge delivery while rejecting sub-10 ns glitches. |
Use Scenario: Enabling/disabling clock or data signals in test equipment or programmable logic interfaces. IC Role / Device Role / Timing Role: Active-low gated buffer inserting controllable break in signal path. Use Value: High-impedance output when OE high prevents loading or back-driving of source circuitry. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AHCT125DR | Same logic function and specs; SOIC-14 package instead of PDIP-14 | Better thermal performance (θJA = 124.5 °C/W vs. 80 °C/W) but surface-mount only | Select SN74AHCT125DR for automated PCB assembly; SN74AHCT125N remains optimal for prototyping, through-hole boards, or socket-based testing. |
| SN74LVC125A | Lower voltage operation (1.65–3.6 V), higher speed (tPD = 3.5 ns), but not TTL-compatible | Requires level translation when interfacing with 5-V TTL sources; unsuitable for direct replacement | Choose SN74LVC125A only in 3.3-V systems where speed and power efficiency outweigh compatibility needs. |
Compared with SN74AHCT125DR and SN74LVC125A, the SN74AHCT125N uniquely balances 5-V TTL compatibility, through-hole manufacturability, and proven industrial temperature range - making it the preferred choice for legacy-system upgrades and lab-grade validation hardware.
Availability
SN74AHCT125N is available at Aetrix Electronics and suitable for microcontroller interface design, LED driver staging, and switch debouncing applications requiring stable component supply across long-lifecycle industrial programs.
Supply support for SN74AHCT125N 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 and automotive electronics.
The SN74AHCT125N belongs to TI's 74AHCT logic family, engineered for seamless interoperability between TTL and CMOS systems in cost-sensitive, reliability-critical 5-V digital interfaces.
FAQ
What is the operating temperature range for SN74AHCT125N?
The SN74AHCT125N is rated for commercial operation from –40°C to +85°C. This range supports deployment in industrial control panels, test instrumentation, and indoor embedded systems where ambient temperatures remain within standard environmental limits. The device does not meet extended or automotive temperature grades.
Can SN74AHCT125N drive LEDs directly?
Yes, SN74AHCT125N can drive standard indicator LEDs directly: each output delivers up to 8 mA sink/source current at VOL ≤ 0.44 V and VOH ≥ 3.8 V (VCC = 4.5 V). For red/green/yellow LEDs with ~2 V forward voltage, a series resistor of ~390 Ω yields ~8 mA - well within SN74AHCT125N's specified IOL/IOH limits.
How should unused inputs be handled on SN74AHCT125N?
All unused inputs on SN74AHCT125N must be terminated to either VCC or GND - never left floating. TI specifies this to prevent undefined logic states, increased power consumption, and potential oscillation. A 10-kΩ pullup or pulldown resistor is recommended when flexibility is needed; direct connection suffices for permanently fixed logic levels.
Is SN74AHCT125N pin-compatible with other 74-series buffers?
SN74AHCT125N shares identical pinout and function with SN74HCT125, SN74LS125, and SN74ALS125 in the 14-pin PDIP package. However, electrical differences exist: SN74AHCT125N offers TTL-compatible inputs and CMOS outputs, while LS/ALS variants draw higher supply current and have different drive strength. Direct substitution requires verification of VIH/VIL and loading requirements.
What bypass capacitor value is recommended for SN74AHCT125N?
A 0.1-µF ceramic capacitor is recommended for SN74AHCT125N, placed as close as possible to the VCC pin (Pin 14) and GND pin (Pin 7). TI's layout guidelines specify this value to suppress high-frequency noise and stabilize the 5-V supply during output switching transients. Parallel use of a 1-µF capacitor is acceptable for broader frequency coverage.
SN74AHCT125N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- 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:
- 8mA, 8mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 14-PDIP
SN74AHCT125N FAQ
1.How can I place an order for SN74AHCT125N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT125N 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 SN74AHCT125N reliable?
The price and inventory of SN74AHCT125N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT125N is usually 5 days.
3.What payment methods are accepted for SN74AHCT125N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT125N transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHCT125N?
SN74AHCT125N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT125N 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 SN74AHCT125N?
For technical support, including SN74AHCT125N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT125N requirements.
6.How does Aetrix verify that SN74AHCT125N is sourced from the original manufacturer or authorized distributors?
All SN74AHCT125N 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 SN74AHCT125N meets industry standards.
7.What is the process for return or replacement of SN74AHCT125N?
All SN74AHCT125N units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT125N, 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 SN74AHCT125N part is unused and in its original packaging.
Return procedure for SN74AHCT125N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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