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Texas Instruments SN74AHCT125NSR
- Part No.:
- SN74AHCT125NSR
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHCT125NSR.pdf
- Description:
- IC BUFFER NON-INVERT 5.5V 14SOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,727
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Product details
Overview
SN74AHCT125NSR from Texas Instruments is a quadruple 3-state bus buffer gate IC with independent output-enable control per channel, TTL-compatible inputs (VIH = 2 V, VIL = 0.8 V), ±8 mA drive strength at 5 V, and propagation delay ≤6.5 ns (CL = 15 pF). It enables digital signal isolation in microcontroller GPIO expansion, LED driver control, and switch debouncing circuits.
For engineers reviewing the SN74AHCT125NSR datasheet, SN74AHCT125NSR pinout, SN74AHCT125NSR application, or SN74AHCT125NSR equivalent, key selection criteria include its 14-pin SOP package, 4.5–5.5 V operating range, high-impedance output state during power sequencing, and compatibility with legacy TTL logic levels in mixed-voltage systems.
Technical Context
The SN74AHCT125NSR implements four independent non-inverting buffers, each with dedicated active-low output-enable (OE) input. When OE is low, A→Y pass-through occurs; when OE is high, Y enters high-impedance state. This architecture supports bidirectional bus control and signal gating without contention.
It uses advanced CMOS technology with TTL-input thresholds, ensuring interoperability with 5 V TTL outputs while maintaining CMOS power efficiency. The device features latch-up immunity >250 mA per JESD 17 and operates across –40°C to +85°C, making it suitable for industrial-grade digital interface conditioning.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5–5.5 V - Ensures stable operation with standard 5 V rails and tolerance for supply ripple or droop. |
| Input Thresholds | VIH = 2 V, VIL = 0.8 V - Directly interfaces with 5 V TTL outputs without level shifting. |
| Output Drive | ±8 mA at VOH/VOL - Sufficient to drive multiple 74-series inputs or small LEDs directly. |
| Propagation Delay | tPLH/tPHL ≤ 6.5 ns (CL = 15 pF) - Supports 100+ MHz data rates in short-bus applications. |
| Quiescent Current | ICC ≤ 20 µA - Enables low-power standby in battery-backed or always-on systems. |
| Input Capacitance | Ci = 10 pF - Minimizes loading on upstream drivers and preserves signal integrity. |
| Thermal Resistance | θJA = 76 °C/W (NS package) - Allows reliable operation up to 85°C ambient without forced cooling. |
Pinout & Package
SN74AHCT125NSR is housed in a 14-pin SOP (Small Outline Package) with 1.27 mm pitch, JEDEC MS-012 compliant, and RoHS-compliant NiPdAu lead finish. Pin 1 is marked by a beveled corner or dot; the package is surface-mount, moisture-sensitive Level-1 (unlimited floor life).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 2OE, 3OE, 4OE | Active-low output enable | Individually disables each buffer's output to high-Z; tie all together for synchronous control. |
| 1A–4A | Buffer input | Non-inverting data input per channel; accepts TTL-level signals directly. |
| 1Y–4Y | Buffer output | 3-state output; drives loads only when corresponding OE is low. |
| VCC (Pin 14) | Power supply | 5 V nominal supply; requires local 0.1 µF bypass capacitor adjacent to pin. |
| GND (Pin 7) | Ground reference | Return path for all I/O and supply currents; connect to solid ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| TTL-compatible inputs | Accepts 5 V TTL logic levels (0.8 V/2 V thresholds) without external biasing or level shifters. |
| Independent 3-state control | Four separate OE pins allow selective isolation of individual data lines in multiplexed buses. |
| High noise immunity | Guaranteed VOL ≤ 0.44 V and VOH ≥ 3.8 V at 8 mA load ensures robust logic margins. |
| Power-up/down high-Z safety | OEs default to high-Z when un-driven; pull OE to VCC via resistor to ensure safe startup state. |
| Low dynamic power | Cpd = 14 pF enables <1 mW typical switching power at 1 MHz, reducing thermal load. |
Applications
| Microcontroller GPIO Expansion | LED Indicator Control |
|---|---|
Use Scenario: A microcontroller with limited GPIO pins routes shared signals (e.g., SPI MISO/MOSI) through SN74AHCT125NSR to isolate peripherals during reconfiguration. IC Role / Device Role / Timing Role: Acts as a digitally controlled signal gate, enabling/disabling data paths under firmware control with sub-7 ns latency. Use Value: Eliminates need for discrete MOSFET switches or complex PCB routing; reduces BOM count and layout area. |
Use Scenario: Driving multiple status LEDs from a single microcontroller port where current sourcing capability is insufficient. IC Role / Device Role / Timing Role: Functions as a current-boosting buffer with 3-state capability to turn LEDs on/off without sinking current through MCU pins. Use Value: Provides ±8 mA per channel-enough to drive standard 20 mA LEDs at 40% duty cycle-while preserving MCU I/O integrity. |
| Switch Debouncing Circuit | Noise-Immune Digital Signal Conditioning |
Use Scenario: Cleaning mechanical switch bounce in industrial HMI panels before feeding clean edges to interrupt inputs. IC Role / Device Role / Timing Role: Buffers and gates switch signals using synchronized OE control; eliminates slow/ringing transitions per TI application guidance. Use Value: Replaces RC + Schmitt-trigger solutions with deterministic, temperature-stable timing and no component aging drift. |
Use Scenario: Isolating noisy sensor interface lines (e.g., from encoders or relays) before entering sensitive logic or ADC sampling circuitry. IC Role / Device Role / Timing Role: Provides high-impedance isolation during inactive periods and fast edge transmission when enabled. Use Value: Prevents noise coupling between subsystems; maintains signal fidelity with <1 ns skew between channels (tsk(o) ≤ 1 ns). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC125APWR | Lower voltage range (1.65–3.6 V); CMOS-only inputs (no TTL compatibility); 24 mA drive. | Suitable for 3.3 V systems only; cannot replace SN74AHCT125NSR in 5 V TTL environments. | Select when migrating to 3.3 V logic families and requiring higher drive strength. |
| 74HC125D,653 | Wider supply range (2–6 V); slower max speed (tPD ≈ 18 ns); no guaranteed TTL input compatibility. | Acceptable for cost-sensitive 5 V designs where timing margin allows; lacks VIH/VIL guarantees for TTL interfacing. | Choose for legacy 74HC-based designs where timing slack exists and TTL interoperability is not required. |
Compared with SN74LVC125APWR and 74HC125D,653, the SN74AHCT125NSR uniquely delivers guaranteed TTL input compatibility at 5 V with sub-7 ns timing-critical for retrofitting into existing 5 V systems without redesigning upstream drivers or adding level shifters.
Availability
SN74AHCT125NSR is available at Aetrix Electronics and suitable for industrial HMI, embedded controller I/O expansion, and LED driver applications requiring stable component supply and long-term production continuity.
Supply support for SN74AHCT125NSR 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 90 years of innovation in industrial, automotive, and communications markets.
The SN74AHCT logic family was designed specifically for seamless integration between legacy TTL systems and modern CMOS logic, delivering pin-compatible upgrades with improved power efficiency and noise immunity.
FAQ
What is the recommended power supply decoupling for SN74AHCT125NSR?
A 0.1 µF ceramic capacitor must be placed as close as possible to the VCC (Pin 14) and GND (Pin 7) pins of the SN74AHCT125NSR to suppress high-frequency noise and stabilize the supply during switching transients. TI recommends mounting it directly adjacent to the package with minimal trace length; paralleling with a 1 µF capacitor further improves broadband suppression across 10 kHz–100 MHz.
Can SN74AHCT125NSR drive LEDs directly?
Yes, SN74AHCT125NSR can drive standard 20 mA LEDs directly in sink or source configuration, as each output delivers ±8 mA at VOH ≥ 3.8 V and VOL ≤ 0.44 V (VCC = 5 V). For continuous operation, limit LED current to ≤6 mA per channel using series resistors to stay within SOA limits and avoid thermal derating at elevated ambient temperatures.
How should unused inputs be handled on SN74AHCT125NSR?
All unused inputs on SN74AHCT125NSR-including A and OE pins-must be terminated to either VCC or GND to prevent floating states that cause excessive ICC, oscillation, or ESD susceptibility. TI specifies a 10 kΩ pull-up or pull-down resistor as optimal for most cases, balancing leakage current, transition speed, and board space constraints.
Is SN74AHCT125NSR compatible with 3.3 V microcontrollers?
SN74AHCT125NSR is not 3.3 V–compatible as an input receiver: its VIH minimum is 2.0 V, but VIL maximum is 0.8 V-so 3.3 V logic HIGHs are accepted, yet 3.3 V logic LOWs may not meet VIL spec reliably. As an output driver, it produces 5 V logic levels, which may damage 3.3 V–only inputs unless clamped or level-shifted.
What is the maximum capacitive load SN74AHCT125NSR can drive while meeting datasheet timing specs?
SN74AHCT125NSR meets all switching specifications-including tPLH ≤ 6.5 ns and tPHL ≤ 6.5 ns-up to CL = 15 pF. At CL = 50 pF, delays increase to ≤8.5 ns, still functional but outside guaranteed spec limits. TI explicitly advises against exceeding 50 pF total load capacitance to maintain signal integrity and avoid excessive rise/fall time degradation.
SN74AHCT125NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- Package/Case:
- 14-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- Surface Mount
- Supplier Device Package:
- 14-SO
SN74AHCT125NSR FAQ
1.How can I place an order for SN74AHCT125NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT125NSR 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 SN74AHCT125NSR reliable?
The price and inventory of SN74AHCT125NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT125NSR is usually 5 days.
3.What payment methods are accepted for SN74AHCT125NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT125NSR transactions.
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4.How is shipping managed for SN74AHCT125NSR?
SN74AHCT125NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT125NSR 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 SN74AHCT125NSR?
For technical support, including SN74AHCT125NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT125NSR requirements.
6.How does Aetrix verify that SN74AHCT125NSR is sourced from the original manufacturer or authorized distributors?
All SN74AHCT125NSR 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 SN74AHCT125NSR meets industry standards.
7.What is the process for return or replacement of SN74AHCT125NSR?
All SN74AHCT125NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT125NSR, 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 SN74AHCT125NSR part is unused and in its original packaging.
Return procedure for SN74AHCT125NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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