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Texas Instruments SN74HCT125DR
- Part No.:
- SN74HCT125DR
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74HCT125DR.pdf
- Description:
- IC BUF NON-INVERT 5.5V 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:7,781
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Product details
Overview
SN74HCT125DR from Texas Instruments is a quadruple 3-state bus buffer gate IC with TTL-compatible inputs and independent enable control per channel, operating at 4.5–5.5 V, delivering ±6-mA output drive, 12-ns typical propagation delay (CL = 50 pF), and 80-µA max supply current - used for bidirectional data bus isolation and memory address buffering in industrial control and embedded systems.
For engineers reviewing the SN74HCT125DR datasheet, SN74HCT125DR pinout, SN74HCT125DR application, or SN74HCT125DR equivalent, key selection criteria include 3-state output timing (ten/tdis ≤ 35 ns), SOIC-14 thermal resistance (RθJA = 138.7 °C/W), input voltage compatibility (VIH = 2 V min, VIL = 0.8 V max), and high-current drive capability for LSTTL loads.
Technical Context
This device implements four independent non-inverting buffers (Y = A) with individual 3-state output-enable (OE) inputs, each disabling its output to high-impedance when OE = HIGH. The logic family is HCT (High-Speed CMOS with TTL input thresholds), ensuring direct replacement of legacy 74LS125 in 5-V systems without level-shifting.
Each channel operates with rail-to-rail output swing (VOH ≥ 3.7 V, VOL ≤ 0.33 V at IO = ±6 mA), supports CL = 50 pF and CL = 150 pF load conditions, and maintains stable operation across –40°C to +85°C ambient temperature with no floating-input tolerance - all unused inputs must be tied to VCC or GND.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - ensures compatibility with standard 5-V TTL and CMOS logic rails without regulation overhead. |
| Propagation Delay (tpd) | 10–22 ns (VCC = 5.5 V, CL = 50 pF) - enables reliable 45-MHz bus operation with margin for setup/hold timing. |
| Output Drive | ±6 mA at 5 V - directly drives up to 15 LSTTL loads without external buffers, reducing BOM count. |
| Input Compatibility | TTL-voltage thresholds (VIH = 2 V, VIL = 0.8 V) - allows seamless interfacing with legacy 74LS/74ALS outputs. |
| Quiescent Current (ICC) | 80 µA max - supports low-static-power system design in always-on industrial monitoring nodes. |
| 3-State Enable/Disable Time | ten ≤ 31 ns, tdis ≤ 30 ns (VCC = 5.5 V, CL = 50 pF) - ensures clean bus arbitration with minimal contention window. |
| Operating Temperature | –40°C to +85°C - qualified for extended-temperature industrial automation and motor control applications. |
Pinout & Package
SN74HCT125DR is housed in a 14-pin SOIC (D) package measuring 8.65 mm × 3.90 mm with 1.27-mm lead pitch and 1.75-mm max height, optimized for automated SMT assembly and thermal performance (RθJA = 138.7 °C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 4, 10, 13 | OE₁–OE₄ (Active-Low Output Enable) | Individually disables corresponding Y output to high-impedance; tie to VCC via pullup for power-up safety. |
| 2, 5, 11, 14 | A₁–A₄ (Input) | TTL-compatible digital input; must not float - connect unused inputs to VCC or GND. |
| 3, 6, 12, 9 | Y₁–Y₄ (3-State Output) | Non-inverting buffered output; presents high-Z state when OE = HIGH, full drive otherwise. |
| 7 | GND | Ground reference for all logic and power domains; requires low-inductance connection to PCB ground plane. |
| 14 | VCC | 5-V supply input; requires local 0.1-μF ceramic bypass capacitor placed within 3 mm of pin. |
Key Features
| Feature | Design Value |
|---|---|
| Independent 3-state control per channel | Enables selective bus segment isolation without affecting other channels - critical for multi-master arbitration. |
| TTL-compatible input thresholds | Eliminates need for level translators when interfacing with 74LS, 74ALS, or microcontroller GPIOs in 5-V systems. |
| Low ICC (80 µA max) | Reduces system standby power in battery-backed or energy-sensitive industrial controllers. |
| High-output current (±6 mA) | Drives heavy capacitive loads (e.g., long PCB traces, multiple inputs) without signal degradation or added drivers. |
| Guaranteed timing over full temp/voltage range | Ensures deterministic bus handshaking in real-time PLC I/O modules where jitter or delay variation is unacceptable. |
Applications
| Industrial Bus Isolation | Memory Address Buffering |
|---|---|
|
Use Scenario: Isolating RS-485 transceiver data lines from MCU GPIOs in programmable logic controllers to prevent bus contention during reset. IC Role / Device Role / Timing Role: SN74HCT125DR acts as a direction-controlled bidirectional buffer, enabling clean half-duplex data flow with sub-35-ns enable/disable transitions. Use Value: Prevents data corruption during power sequencing by forcing high-Z state on transceiver side until MCU firmware initializes control pins. |
Use Scenario: Driving 16-bit address lines from an 8-bit microcontroller to external SRAM in a compact industrial HMI panel. IC Role / Device Role / Timing Role: SN74HCT125DR provides four parallel non-inverting buffers with matched propagation delay to maintain address setup/hold integrity. Use Value: Eliminates skew-induced address glitches that could cause memory read/write errors at 10-MHz bus speeds. |
| Legacy System Interface | Digital I/O Expansion |
|
Use Scenario: Interfacing modern ARM-based controller GPIOs to legacy 74LS-based peripheral cards in test equipment racks. IC Role / Device Role / Timing Role: SN74HCT125DR serves as a level- and timing-compatible bridge, translating 3.3-V logic levels to 5-V TTL while preserving edge rates. Use Value: Avoids redesign of aging backplane wiring by maintaining original 74LS125 timing margins and fanout capability. |
Use Scenario: Expanding GPIO count for sensor polling in a DIN-rail mounted IoT gateway using shared I²C/SPI buses. IC Role / Device Role / Timing Role: SN74HCT125DR isolates sensor enable lines from main bus, preventing capacitive loading and signal integrity loss. Use Value: Enables simultaneous activation of eight analog sensors without degrading SPI clock edge fidelity or increasing MCU software overhead. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT125N | Same logic function and electrical specs, but in 14-pin PDIP (19.31 mm × 6.35 mm) with higher thermal mass and RθJA = 75.3 °C/W. | Preferred for prototyping, through-hole assembly, or high-temperature environments requiring lower junction rise per watt. | Select SN74HCT125N when manual soldering, breadboarding, or thermal derating above 138.7 °C/W is required. |
| 74LVC125APW | Lower VCC range (1.65–3.6 V), 3.3-V native logic, 3.5-ns tpd, but incompatible TTL input thresholds (VIH = 2 V only at VCC = 3.3 V). | Suitable for modern low-voltage mixed-signal systems but requires level-shifting or redesign if replacing 5-V TTL interfaces. | Choose 74LVC125APW only when migrating fully to 3.3-V architecture and verifying input threshold compatibility with upstream drivers. |
Compared with SN74HCT125N and 74LVC125APW, SN74HCT125DR offers optimal balance of 5-V TTL interoperability, SOIC-14 manufacturability, and thermal performance for volume industrial PCBs - neither alternative matches its exact 5-V/3-state/TTL-input niche without trade-offs in voltage, package, or interface compatibility.
Availability
SN74HCT125DR is available at Aetrix Electronics and suitable for industrial bus isolation, memory address buffering, legacy system interface, and digital I/O expansion requiring stable component supply and long-term production continuity.
Supply support for SN74HCT125DR 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 connectivity technologies, with over 50 years of innovation in logic and interface solutions.
The SN74HCT125DR belongs to TI's legacy 74HCT logic family, designed specifically for drop-in replacement of bipolar TTL in 5-V industrial and automotive systems while delivering CMOS power efficiency and noise immunity.
FAQ
What is the maximum capacitive load SN74HCT125DR can drive while maintaining specified timing?
SN74HCT125DR is characterized for CL = 50 pF and CL = 150 pF loads. At CL = 150 pF and VCC = 5.5 V, propagation delay remains within spec (tpd ≤ 48 ns), and transition time stays ≤ 57 ns. For loads exceeding 150 pF, timing margins degrade - use series termination or reduce trace length to stay within 150-pF limit for guaranteed operation.
Can SN74HCT125DR operate reliably at 4.2 V supply?
No - SN74HCT125DR has a minimum recommended supply voltage of 4.5 V per TI's datasheet. At 4.2 V, VIH and VOL specifications are not guaranteed, input thresholds may shift, and output drive falls below ±6 mA, risking misreads in TTL-connected systems. Use only within 4.5–5.5 V range.
How should unused inputs be handled on SN74HCT125DR?
All unused inputs on SN74HCT125DR - including A and OE pins - must be tied to either VCC or GND. Floating inputs cause increased ICC, unpredictable output states, and potential oscillation. For OE pins, tie to VCC via 10-kΩ pullup to ensure high-Z default on power-up; for unused A inputs, tie to GND or VCC based on desired default output state.
Is SN74HCT125DR RoHS compliant and lead-free?
Yes - SN74HCT125DR is RoHS-compliant with NIPDAU (nickel/palladium/gold) lead finish and meets JEDEC Level-1 moisture sensitivity (260°C peak reflow). The part marking "HCT125" and tape-and-reel packaging (2500 units per reel) confirm full compliance per TI's Package Option Addendum dated November 2025.
Does SN74HCT125DR support hot-swap or live-insertion?
No - SN74HCT125DR lacks hot-swap protection circuitry. Applying VCC before GND, or connecting outputs to a powered bus, risks latch-up or damage due to back-powering through ESD diodes. Always power GND first, then VCC, and ensure OE is held HIGH until power stabilization to avoid bus contention.
SN74HCT125DR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 14-SOIC (0.154", 3.90mm 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:
- 6mA, 6mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SOIC
SN74HCT125DR FAQ
1.How can I place an order for SN74HCT125DR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HCT125DR 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 SN74HCT125DR reliable?
The price and inventory of SN74HCT125DR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HCT125DR is usually 5 days.
3.What payment methods are accepted for SN74HCT125DR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HCT125DR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HCT125DR?
SN74HCT125DR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HCT125DR 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 SN74HCT125DR?
For technical support, including SN74HCT125DR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HCT125DR requirements.
6.How does Aetrix verify that SN74HCT125DR is sourced from the original manufacturer or authorized distributors?
All SN74HCT125DR 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 SN74HCT125DR meets industry standards.
7.What is the process for return or replacement of SN74HCT125DR?
All SN74HCT125DR units undergo pre-shipment inspection (PSI). If there is an issue with SN74HCT125DR, 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 SN74HCT125DR part is unused and in its original packaging.
Return procedure for SN74HCT125DR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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