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Texas Instruments SN74F125D
- Part No.:
- SN74F125D
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74F125D.pdf
- Description:
- IC BUF NON-INVERT 5.5V 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,214
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Product details
Overview
SN74F125D from Texas Instruments is a quadruple bus buffer gate with 3-state outputs, designed for bidirectional data bus isolation and memory address register buffering in TTL-compatible systems. It features four independent noninverting buffers, each with separate output-enable (OE) control, 5 V supply operation, 6.5 ns max propagation delay at 5 V/50 pF, and ±64 mA low-state output drive capability.
For engineers reviewing the SN74F125D datasheet, SN74F125D pinout, SN74F125D application, or SN74F125D equivalent, this device is selected for legacy TTL bus interfacing where controlled tri-state enable timing, deterministic output disable behavior, and compatibility with 74F logic families are required.
Technical Context
The SN74F125D implements four independent noninverting buffer stages, each with dedicated active-low output-enable control. Its 3-state outputs support high-impedance disconnection of data lines during bus arbitration or power-down sequencing.
It operates strictly within 4.5 V to 5.5 V supply range and is characterized for 0°C to 70°C ambient temperature. Input thresholds are fixed at VIH = 2 V (min) and VIL = 0.8 V (max), ensuring robust noise margin against TTL-level signals.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures compatibility with standard 5 V TTL systems and accommodates rail tolerance without functional degradation. |
| Propagation Delay (tPLH/tPHL) | 1.2 ns (min) to 6.5 ns (max) at VCC = 4.5–5.5 V, CL = 50 pF - Defines maximum timing budget for signal routing between source and destination on shared buses. |
| Output Drive (IOL) | 64 mA (max) - Supports driving multiple TTL inputs or moderate capacitive loads (≤50 pF) without external buffering. |
| 3-State Disable Time (tPZL) | 3.2 ns (min) to 9 ns (max) - Determines minimum interval required after OE assertion before bus contention risk is eliminated. |
| Input Clamp Current | –18 mA - Allows safe handling of transient overvoltage events up to –1.2 V at inputs without latch-up or damage. |
| Quiescent Supply Current (ICCL) | 28–40 mA at VCC = 5.5 V - Reflects worst-case static power draw when all outputs are actively driven low. |
Pinout & Package
SN74F125D is housed in a 14-pin SOIC (D) package with 1.27 mm pitch, 8.75 mm × 3.91 mm body, and 1.75 mm max height. Pin 1 is marked by a beveled corner or notch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 4, 10, 13 | OE (Output Enable) | Active-low control per buffer; high = high-Z output, low = enabled noninverting pass-through. |
| 2, 5, 11, 14 | A (Input) | Noninverting data input for corresponding buffer stage. |
| 3, 6, 12, 9 | Y (Output) | 3-state buffered output; mirrors A when OE is low, high-impedance when OE is high. |
| 7 | GND | Ground reference for logic and power return path. |
| 14 | VCC | +5 V supply connection; decoupling capacitor placement near this pin is critical for noise suppression. |
Key Features
| Feature | Design Value |
|---|---|
| Independent 3-state control per channel | Enables selective bus segment isolation without affecting other channels - essential for multi-master arbitration in legacy backplanes. |
| Guaranteed 5 V TTL compatibility | VIH/VIL thresholds and output voltage levels meet 74F family specs - eliminates level-shifting in mixed-F-series designs. |
| Low propagation delay variation | tPLH/tPHL mismatch ≤ 1.5 ns across channels - preserves skew-critical timing in parallel data paths like address latches. |
| High-current sink capability | 64 mA IOL supports direct drive of up to 10 standard TTL loads - reduces need for additional drivers in dense board layouts. |
| Robust input overvoltage tolerance | –1.2 V to 7 V input range with clamp diodes - protects against hot-plug transients and ESD events common in industrial rack systems. |
Applications
| Memory Address Buffering | Legacy Bus Isolation |
|---|---|
|
Use Scenario: Driving address lines from a microprocessor to multiple memory chips on a shared bus. IC Role / Device Role / Timing Role: Noninverting buffer with per-line OE control isolates address decoding logic from memory chip enable timing. Use Value: Prevents address bus contention during memory bank switching; enables clean transitions with <9 ns disable time. |
Use Scenario: Interfacing two independent 5 V TTL subsystems sharing a common data bus. IC Role / Device Role / Timing Role: Bidirectional bus buffer with independent OE pins allows direction-controlled data flow without external direction logic. Use Value: Eliminates bus conflicts during handshaking; supports deterministic arbitration using synchronized OE strobes. |
| Peripheral Interface Expansion | Industrial Control Backplane |
|
Use Scenario: Expanding I/O capacity of an 8-bit microcontroller by adding parallel peripheral devices. IC Role / Device Role / Timing Role: Data path buffer that gates peripheral access via software-controlled OE signals. Use Value: Enables dynamic peripheral enable/disable without hardware redesign; maintains signal integrity across 15 cm PCB traces. |
Use Scenario: Signal conditioning and isolation in programmable logic controller (PLC) backplane modules. IC Role / Device Role / Timing Role: Level-consistent repeater for status and command signals between isolated rack segments. Use Value: Provides noise-immune signal regeneration with guaranteed 2 V VIH margin - critical in electrically noisy factory environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS125N | Slower propagation (15 ns max), lower drive (8 mA IOL), higher ICCZ (10 mA), compatible pinout. | Lower speed/power trade-off; suitable only where timing margins exceed 10 ns. | Select when legacy LS-family compatibility is mandatory and system clock rate ≤ 10 MHz. |
| SN74ACT125D | Faster (3.5 ns max tPLH), CMOS input (1 µA IIH), wider VCC range (4.5–5.5 V), same pinout. | Improved noise immunity and reduced static power, but requires careful handling of unused inputs. | Choose for new designs needing higher speed and lower quiescent current while retaining layout compatibility. |
Compared with SN74F125D, SN74LS125N offers lower cost and proven reliability in slow-speed industrial controls but sacrifices timing performance; SN74ACT125D delivers superior speed and input leakage control but demands stricter input biasing per TI SCBA004 guidelines.
Availability
SN74F125D is available at Aetrix Electronics and suitable for memory address buffering, legacy bus isolation, and peripheral interface expansion requiring stable component supply and long-term obsolescence management.
Supply support for SN74F125D 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 founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74F125D belongs to TI's 74F logic family, engineered for high-speed TTL-compatible digital interfacing in systems where predictable timing, bus contention avoidance, and backward compatibility with 74-series logic are design priorities.
FAQ
What is the function of the OE pin on the SN74F125D?
The OE (output-enable) pin on the SN74F125D is an active-low control input for each of the four independent buffer channels. When OE is low, the corresponding Y output follows the A input; when OE is high, the Y output enters high-impedance (3-state) mode. This behavior is confirmed in the function table and logic diagram of the SN74F125D datasheet, enabling precise bus arbitration and signal isolation.
Can SN74F125D operate at 3.3 V supply voltage?
No, SN74F125D is not rated for 3.3 V operation. Its recommended operating conditions specify a minimum supply voltage of 4.5 V and maximum of 5.5 V. Operating below 4.5 V may result in undefined logic thresholds, increased propagation delay, or failure to drive TTL loads reliably. For 3.3 V systems, consider SN74LVC125A or similar LVCMOS-compatible alternatives.
What is the maximum capacitive load the SN74F125D can drive reliably?
The SN74F125D is characterized for CL = 50 pF in its switching specifications, with propagation delays and timing parameters guaranteed under that condition. While it may drive higher capacitance, exceeding 50 pF increases propagation delay nonlinearly and risks setup/hold violations. For loads >50 pF, add series termination or use a driver with higher IOL, such as SN74F244.
How does SN74F125D handle unused inputs?
All unused inputs of the SN74F125D must be tied to either VCC or GND to prevent floating states that cause excessive ICC current and potential oscillation. This requirement is explicitly stated in Note 3 of the SN74F125D datasheet and applies to both A and OE inputs. Leaving them unconnected violates recommended operating conditions and compromises device reliability.
Is SN74F125D pin-compatible with SN74F126D?
No, SN74F125D is not pin-compatible with SN74F126D. Although both are quad buffers, SN74F126D features inverting outputs and different pin assignments: its OE pins are located at pins 1, 4, 10, and 13 (same as SN74F125D), but its input/output pairing differs - for example, SN74F126D pin 2 is Y (inverted), not A. Substituting them without board revision will cause logic inversion errors.
SN74F125D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74F
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Bulk
- 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:
- 15mA, 64mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SOIC
SN74F125D FAQ
1.How can I place an order for SN74F125D through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74F125D 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 SN74F125D reliable?
The price and inventory of SN74F125D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74F125D is usually 5 days.
3.What payment methods are accepted for SN74F125D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74F125D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74F125D?
SN74F125D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74F125D 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 SN74F125D?
For technical support, including SN74F125D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74F125D requirements.
6.How does Aetrix verify that SN74F125D is sourced from the original manufacturer or authorized distributors?
All SN74F125D 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 SN74F125D meets industry standards.
7.What is the process for return or replacement of SN74F125D?
All SN74F125D units undergo pre-shipment inspection (PSI). If there is an issue with SN74F125D, 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 SN74F125D part is unused and in its original packaging.
Return procedure for SN74F125D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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