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Texas Instruments SN74BCT125ADR
- Part No.:
- SN74BCT125ADR
- Manufacturer:
- Texas Instruments
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
SN74BCT125ADR.pdf
- Description:
- IC BUF NON-INVERT 5.5V 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,534
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Product details
Overview
SN74BCT125ADR 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 5-V TTL-compatible systems. It operates from 4.5 V to 5.5 V, delivers 128 mA low-level output current, and features BiCMOS architecture that reduces ICCZ standby current to 6–14 mA. Used in industrial control backplanes and legacy computing address latching.
For engineers reviewing the SN74BCT125ADR datasheet, SN74BCT125ADR pinout, SN74BCT125ADR application, or SN74BCT125ADR equivalent, key selection criteria include 3-state enable timing (tPZH/tPLZ ≤ 7.4 ns), output drive strength (IOL = 64 mA), input compatibility with TTL/CMOS logic families, and SOIC-14 packaging for high-density PCB layouts.
Technical Context
This device implements four independent non-inverting buffers, each with an active-low output-enable (OE) control line. Each buffer transitions to high-impedance when its OE is high, enabling bus sharing without contention. The BiCMOS design combines bipolar input stages for TTL-level recognition and CMOS output stages for low power and high speed.
Propagation delays are tightly specified: tPLH/tPHL ≤ 5.7 ns at VCC = 5 V, CL = 50 pF; enable/disable times (tPZH/tPLZ/tPZL) range from 3.0 ns to 10.3 ns. Input thresholds meet TTL standards (VIH = 2.0 V min, VIL = 0.8 V max), and outputs drive standard 50-Ω transmission lines under load.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures compatibility with regulated 5-V TTL and mixed-signal systems without level-shifting. |
| Output Drive (IOL) | 64 mA - Sustains robust signal integrity across loaded buses up to 12-inch FR-4 traces. |
| Propagation Delay | ≤5.7 ns (tPLH/tPHL) - Supports >100 MHz bus toggle rates in synchronous address/data paths. |
| 3-State Enable Time | tPZH ≤ 7.4 ns - Enables fast bus arbitration in multiprocessor or DMA-controlled architectures. |
| Input Thresholds | VIH ≥ 2.0 V, VIL ≤ 0.8 V - Guarantees reliable interfacing with legacy 74LS, 74F, and microcontroller GPIOs. |
| Quiescent Current (ICCZ) | 6–14 mA - Minimizes power in idle 3-state mode versus older bipolar-only buffers (e.g., 74LS125). |
| Package | SOIC-14 (D package) - Industry-standard 150-mil width, 1.27-mm pitch, RoHS-compliant NIPDAU finish. |
Pinout & Package
SN74BCT125ADR uses a 14-pin SOIC (D) package with 1.27-mm lead pitch and 1.75-mm maximum height. Pin 1 is marked by a beveled corner or notch on the top surface.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 4, 10, 13 | Output Enable (1OE, 2OE, 3OE, 4OE) | Active-low control per buffer; tie to VCC via pullup for power-up high-Z safety. |
| 2, 5, 11, 14 | Input (1A, 2A, 3A, 4A) | TTL-compatible inputs accepting 0.8 V / 2.0 V thresholds; must not float. |
| 3, 6, 12, 9 | Output (1Y, 2Y, 3Y, 4Y) | 3-state totem-pole outputs capable of sinking 64 mA or sourcing –15 mA. |
| 7 | GND | Ground reference for all logic and output stages; requires low-inductance connection. |
| 14 | VCC | 5-V supply rail; bypass with 0.1 µF ceramic capacitor near pin for noise suppression. |
Key Features
| Feature | Design Value |
|---|---|
| BiCMOS process technology | Reduces ICCZ quiescent current by >50% vs. pure bipolar 74BCT125, lowering system heat load. |
| Independent 3-state controls | Enables selective bus segment isolation-e.g., disable only memory address lines while keeping data lines active. |
| TTL-compatible input thresholds | Eliminates need for external level shifters when interfacing with 74LS, 74F, or 8051-family microcontrollers. |
| High sink current (64 mA) | Drives multiple TTL loads (fan-out ≥ 20) or terminates unterminated stubs in backplane applications. |
| SOIC-14 tape-and-reel packaging | Supports automated SMT assembly at 2500 units/reel with MSL Level-1 rating for unlimited floor life. |
Applications
| Industrial Backplane Bus Isolation | Memory Address Register Buffering |
|---|---|
Use Scenario: Isolating CPU address/data buses from peripheral expansion slots in programmable logic controllers. IC Role / Device Role / Timing Role: Quad buffer provides independent 3-state control per bus segment to prevent contention during hot-swap or configuration changes. Use Value: Enables deterministic bus arbitration with <7.4 ns enable delay and 64 mA drive to overcome trace capacitance up to 100 pF. |
Use Scenario: Latching and driving 16-bit address lines from a microcontroller to SRAM or EPROM in embedded instrumentation. IC Role / Device Role / Timing Role: Non-inverting buffer with TTL-compatible inputs translates MCU GPIO levels to full-rail 5-V address signals. Use Value: VIH/VIL specs ensure reliable sampling at 0–70°C; 5.7 ns propagation supports 10-MHz address setup/hold timing. |
| Legacy Computer System Interface | Test Equipment Signal Routing |
Use Scenario: Interfacing ISA-bus peripherals with modern FPGA-based controllers in retro-computing test rigs. IC Role / Device Role / Timing Role: Bidirectional bus transceiver replacement using discrete enable-controlled buffers for direction management. Use Value: 4.5–5.5 V operation matches ISA spec; 128 mA IOL handles legacy bus loading without external drivers. |
Use Scenario: Multiplexing stimulus signals between DUT pins and ATE channel resources in automated functional testers. IC Role / Device Role / Timing Role: 3-state output gating routes calibrated analog/digital signals while preventing backdrive into source ICs. Use Value: High-Z leakage <±50 µA ensures signal integrity during off-state; fast disable (<10.3 ns) minimizes crosstalk windows. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS125N | Lower drive (IOL = 24 mA), higher ICCZ (36 mA), slower tPLH (15 ns), PDIP-14 only. | Suitable for low-speed, low-power legacy designs where fan-out ≤ 10 is acceptable. | Choose SN74LS125N only if board space allows PDIP and timing budget permits >2× delay penalty. |
| SN74AHCT125DR | CMOS input (VIH = 3.5 V), same SOIC-14, lower ICCZ (2 µA), but reduced IOL (8 mA). | Better for 3.3-V system interfacing with 5-V tolerant inputs; insufficient for heavy bus loading. | Select SN74AHCT125DR when interfacing with 3.3-V controllers and bus loads < 4 TTL units. |
Compared with SN74LS125N, SN74BCT125ADR delivers 2.7× higher drive and 5× faster timing; versus SN74AHCT125DR, it trades ultra-low standby current for 8× greater sink capability-critical for legacy 5-V bus termination.
Availability
SN74BCT125ADR is available at Aetrix Electronics and suitable for industrial backplane bus isolation, memory address register buffering, and legacy computer system interface applications requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74BCT125ADR 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 SN74BCT125ADR belongs to TI's legacy BCT logic family, engineered specifically for high-drive, 5-V TTL-compatible bus interfacing in mission-critical industrial and defense systems requiring reliability across temperature extremes.
FAQ
What is the recommended power-up sequence for SN74BCT125ADR to avoid bus contention?
TI recommends tying all OE pins to VCC through a pullup resistor (value determined by driver sink capability) before applying VCC. This ensures all outputs enter high-impedance state at power-on. For SN74BCT125ADR, a 4.7-kΩ resistor suffices given its IIH ≤ 25 µA. Failure to do so may cause transient bus conflicts during voltage ramp-up.
Can SN74BCT125ADR interface directly with 3.3-V microcontrollers?
No-SN74BCT125ADR inputs require VIH ≥ 2.0 V, which is compatible with 3.3-V logic high levels, but its outputs swing rail-to-rail (0 V to 5 V). Direct connection to 3.3-V inputs risks overvoltage damage unless current-limiting resistors or level translators are used. SN74BCT125ADR is intended for 5-V systems only.
What is the maximum capacitive load SN74BCT125ADR can drive while maintaining specified timing?
Per the datasheet, SN74BCT125ADR switching characteristics (tPLH/tPHL ≤ 5.7 ns) are guaranteed with CL = 50 pF. Driving >100 pF increases delay nonlinearly and may exceed 10 ns; for heavier loads, add series termination or reduce trace length. Output rise/fall times remain <3 ns up to 75 pF.
Does SN74BCT125ADR support hot-swap insertion into a live 5-V bus?
SN74BCT125ADR is not hot-swap rated. Its absolute maximum ratings allow VO = –0.5 V to 5.5 V only in disabled or power-off states. During live insertion, uncontrolled VCC ramp and floating OE pins risk latch-up or excessive ICCZ. Use dedicated hot-swap controllers or buffer-enable sequencing circuits when required.
How does the BiCMOS architecture of SN74BCT125ADR improve performance over standard bipolar BCT devices?
SN74BCT125ADR's BiCMOS design replaces bipolar output transistors with CMOS totem-pole stages, cutting ICCZ from ~30 mA (in 74BCT125) to 6–14 mA. This reduces self-heating and improves noise margin without sacrificing 64 mA sink current or 5.7 ns propagation-achieving both speed and efficiency unattainable in pure bipolar processes.
SN74BCT125ADR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74BCT
- 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:
- 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
SN74BCT125ADR FAQ
1.How can I place an order for SN74BCT125ADR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74BCT125ADR 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 SN74BCT125ADR reliable?
The price and inventory of SN74BCT125ADR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT125ADR is usually 5 days.
3.What payment methods are accepted for SN74BCT125ADR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74BCT125ADR transactions.
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4.How is shipping managed for SN74BCT125ADR?
SN74BCT125ADR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74BCT125ADR 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 SN74BCT125ADR?
For technical support, including SN74BCT125ADR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT125ADR requirements.
6.How does Aetrix verify that SN74BCT125ADR is sourced from the original manufacturer or authorized distributors?
All SN74BCT125ADR 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 SN74BCT125ADR meets industry standards.
7.What is the process for return or replacement of SN74BCT125ADR?
All SN74BCT125ADR units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT125ADR, 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 SN74BCT125ADR part is unused and in its original packaging.
Return procedure for SN74BCT125ADR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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