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Texas Instruments SN74AHCT125DG4
- Part No.:
- SN74AHCT125DG4
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74AHCT125DG4.pdf
- Description:
- IC BUF NON-INVERT 5.5V 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,542
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Product details
Overview
SN74AHCT125DG4 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 output drive, and 5 V nominal supply operation. It enables/disables digital signals in data bus isolation, LED control, and switch debouncing applications.
For engineers reviewing the SN74AHCT125DG4 datasheet, SN74AHCT125DG4 pinout, SN74AHCT125DG4 application, or SN74AHCT125DG4 equivalent, this page delivers verified functional role, real-world timing behavior (tPLH/tPHL ≤ 6.5 ns @ 15 pF), thermal performance (θJA = 147.7 °C/W), and precise pin-level design meaning for SOIC-14 implementation.
Technical Context
The SN74AHCT125DG4 implements four independent CMOS buffer gates, each with dedicated active-low output-enable (OE) control. Each gate passes A→Y when OE = LOW and enters high-impedance state when OE = HIGH - enabling bidirectional bus sharing and signal gating without contention.
Its TTL-voltage-compatible inputs accept 0.8 V/2.0 V thresholds across –40°C to +85°C, while output drive capability (±8 mA) and low quiescent current (ICC ≤ 20 µA) support robust interfacing with legacy logic and low-power microcontrollers. Power-up high-impedance is ensured by tying OE to VCC via pullup resistor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage (VCC) | 4.5 V to 5.5 V - defines valid operating range; VOH/VOL specs scale with actual VCC |
| Input Thresholds (VIH/VIL) | 2.0 V / 0.8 V - ensures reliable recognition of standard TTL logic levels |
| Output Drive (IOH/IOL) | –8 mA / +8 mA - supports direct driving of multiple 74-series loads or LEDs with series resistor |
| Propagation Delay (tPLH/tPHL) | ≤6.5 ns @ CL = 15 pF - enables use in 100+ MHz data paths with tight timing budgets |
| Quiescent Current (ICC) | ≤20 µA @ VCC = 5.5 V - minimizes standby power in battery-backed or always-on systems |
| Input Capacitance (Ci) | 10 pF - limits capacitive loading on upstream drivers and preserves signal edge integrity |
| Thermal Resistance (θJA) | 147.7 °C/W (SOIC-14) - determines maximum power dissipation before junction temperature exceeds 150°C |
Pinout & Package
SN74AHCT125DG4 is packaged in 14-pin SOIC (D package), 8.65 mm × 3.91 mm body, 1.27 mm pitch, JEDEC MS-012AC compliant. Pin 1 is top-left corner marker; pin 7 = GND, pin 14 = VCC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1OE, 2OE, 3OE, 4OE | Active-low output enable | Each controls one buffer independently; HIGH forces Y into high-Z; requires pullup for power-up safety |
| 1A–4A | Buffer input | Accepts TTL-compatible signals; must be terminated to VCC/GND if unused to prevent floating |
| 1Y–4Y | Buffer output | 3-state push-pull; drives load when OE = LOW; floats when OE = HIGH; not to be tied directly to VCC/GND |
| VCC (Pin 14) | Positive supply | Must be bypassed with 0.1 µF capacitor placed adjacent to pin; supplies all four buffers |
| GND (Pin 7) | Ground reference | Common return for all outputs and internal logic; requires low-impedance PCB plane connection |
Key Features
| Feature | Design Value |
|---|---|
| TTL-compatible inputs | Accepts 0.8 V/2.0 V thresholds - eliminates level-shifting when interfacing with legacy 74LS or microcontroller GPIO |
| Independent 3-state control | Four separate OE pins allow selective activation of individual data lines - essential for multiplexing or partial bus isolation |
| High-impedance on power-up | OE tied to VCC via pullup ensures outputs remain disabled until system firmware asserts control - prevents bus contention |
| Low dynamic power | Cpd = 14 pF - reduces switching current and EMI in high-frequency clock/data routing applications |
| Latch-up immunity | Exceeds 250 mA per JESD17 - withstands transient overvoltage events without destructive latch-up |
Applications
| Industrial Sensor Interface | Microcontroller GPIO Expansion |
|---|---|
Use Scenario: Isolating analog-to-digital converter (ADC) data bus from noisy motor control circuitry in PLC backplanes. IC Role / Device Role / Timing Role: Bus buffer gate providing directional signal isolation and noise decoupling between ADC and MCU during conversion cycles. Use Value: Prevents digital switching noise from corrupting sensitive analog measurements by enforcing high-Z state during critical sampling windows. |
Use Scenario: Expanding limited GPIO count on an ARM Cortex-M0+ MCU to drive eight discrete LEDs and two status indicators. IC Role / Device Role / Timing Role: Signal gating element enabling time-multiplexed LED control using four shared data lines and independent OE strobes. Use Value: Reduces required MCU pins from 10 to 6 while maintaining independent brightness control and eliminating cross-talk between indicators. |
| Pushbutton Debounce Circuit | Legacy System Bus Interface |
Use Scenario: Conditioning mechanical switch inputs in a medical device front panel where contact bounce must be suppressed below 10 µs. IC Role / Device Role / Timing Role: Digital signal conditioner converting erratic switch transitions into clean, synchronized logic edges for interrupt generation. Use Value: Eliminates need for RC filters or firmware debounce loops - guarantees sub-100 ns response with hardware reliability. |
Use Scenario: Interfacing a modern FPGA-based controller to a legacy ISA bus peripheral requiring 5 V TTL signaling and tristate arbitration. IC Role / Device Role / Timing Role: Level-adapted bus transceiver enabling safe bidirectional data transfer between 3.3 V FPGA I/O and 5 V ISA address/data lines. Use Value: Provides voltage translation and bus contention protection without external resistors or discrete transistors - simplifies adapter board layout. |
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 silicon, SOIC-14 tape-and-reel packaging (2500 pcs/reel); identical electrical specs and pinout | No functional difference; optimized for automated SMT assembly vs. tube-based DG4 | Select DR for high-volume production; DG4 suits prototyping and low-quantity procurement |
| SN74LVC125A | Lower VCC range (1.65–3.6 V); higher speed (tPD ≤ 3.7 ns); CMOS-only inputs (no TTL compatibility) | Requires level-shifting for 5 V systems; unsuitable for direct replacement in legacy TTL environments | Choose only for new 3.3 V designs prioritizing speed/power over backward compatibility |
Compared with SN74AHCT125DG4, SN74AHCT125DR offers identical functionality in volume-friendly packaging, while SN74LVC125A trades TTL compatibility for lower voltage operation and faster switching - making DG4 the sole drop-in solution for existing 5 V TTL-interfaced systems.
Availability
SN74AHCT125DG4 is available at Aetrix Electronics and suitable for industrial sensor interfaces, microcontroller GPIO expansion, pushbutton debounce circuits, and legacy system bus interfacing requiring stable component supply and long-term manufacturability.
Supply support for SN74AHCT125DG4 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 with emphasis on reliability, longevity, and industrial-grade qualification.
The SN74AHCT125DG4 belongs to TI's 74AHCT logic family, engineered specifically for seamless interoperability between 3.3 V and 5 V systems while maintaining TTL input compatibility and robust noise immunity in harsh industrial environments.
FAQ
What is the function of the OE pins on the SN74AHCT125DG4?
Each OE pin (1OE–4OE) is an active-low enable controlling one buffer channel independently. When OE = LOW, the corresponding A input passes to Y; when OE = HIGH, Y enters high-impedance state. For safe power-up, OE pins should be pulled to VCC via resistor - ensuring outputs remain disabled until firmware initializes control.
Can SN74AHCT125DG4 interface directly with 3.3 V microcontrollers?
Yes, SN74AHCT125DG4 accepts 3.3 V logic HIGH as valid VIH (min 2.0 V) and outputs 5 V logic levels compatible with 3.3 V-tolerant inputs. However, its VCC must be 5 V to meet output drive specs; for true bidirectional 3.3 V ↔ 5 V translation, additional level-shifting circuitry is required beyond SN74AHCT125DG4 alone.
What is the maximum capacitive load SN74AHCT125DG4 can drive while meeting datasheet timing specs?
SN74AHCT125DG4 guarantees tPLH/tPHL ≤ 6.5 ns and tPZH/tPLZ ≤ 8 ns only up to CL = 15 pF. At CL = 50 pF, delays increase to ≤ 8.5 ns (propagation) and ≤ 10 ns (enable/disable). Driving >50 pF violates AC specs and risks timing violations - add buffer stages or reduce trace capacitance for heavier loads.
How should unused inputs be handled on SN74AHCT125DG4?
All unused A and OE inputs on SN74AHCT125DG4 must be terminated to VCC or GND - never left floating. A 10 kΩ pullup/pulldown resistor is recommended to ensure defined logic states, prevent oscillation, and minimize leakage-induced current. Floating inputs cause unpredictable output behavior and increased ICC.
Does SN74AHCT125DG4 require external bypass capacitors?
Yes, SN74AHCT125DG4 requires a 0.1 µF ceramic bypass capacitor placed directly between VCC (pin 14) and GND (pin 7), with minimal trace length. This suppresses supply noise during switching transitions. For enhanced noise rejection, pair it with a 1 µF capacitor in parallel - both mounted as close to the SOIC package as possible.
SN74AHCT125DG4 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 ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SOIC
SN74AHCT125DG4 FAQ
1.How can I place an order for SN74AHCT125DG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT125DG4 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 SN74AHCT125DG4 reliable?
The price and inventory of SN74AHCT125DG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT125DG4 is usually 5 days.
3.What payment methods are accepted for SN74AHCT125DG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT125DG4 transactions.
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4.How is shipping managed for SN74AHCT125DG4?
SN74AHCT125DG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT125DG4 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 SN74AHCT125DG4?
For technical support, including SN74AHCT125DG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT125DG4 requirements.
6.How does Aetrix verify that SN74AHCT125DG4 is sourced from the original manufacturer or authorized distributors?
All SN74AHCT125DG4 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 SN74AHCT125DG4 meets industry standards.
7.What is the process for return or replacement of SN74AHCT125DG4?
All SN74AHCT125DG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT125DG4, 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 SN74AHCT125DG4 part is unused and in its original packaging.
Return procedure for SN74AHCT125DG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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