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Texas Instruments SN74AHCT125BQAR
- Part No.:
- SN74AHCT125BQAR
- Manufacturer:
- Texas Instruments
- Package:
- 14-WFQFN Exposed Pad
- Datasheet:
-
SN74AHCT125BQAR.pdf
- Description:
- 4-CH 4.5-V TO 5.5-V BUFFERS
- Quantity:
- Payment:
- Shipping:
Inventory:2,298
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Product details
Overview
SN74AHCT125BQAR 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, and 5 V operation. It isolates or passes digital signals in data bus management, microcontroller GPIO expansion, and signal routing applications.
For engineers reviewing the SN74AHCT125BQAR datasheet, SN74AHCT125BQAR pinout, SN74AHCT125BQAR application, or SN74AHCT125BQAR equivalent, key selection criteria include its WQFN-14 package footprint, 3.8–6.5 ns propagation delay at 15 pF load, high-impedance output state during power sequencing, and compatibility with 5 V CMOS/TTL logic families.
Technical Context
The SN74AHCT125BQAR implements four independent non-inverting buffers, each with dedicated active-low output-enable (OE) control. Each channel transitions between transparent mode (OE = LOW) and high-impedance tri-state (OE = HIGH), enabling bidirectional bus arbitration and signal gating without contention.
It operates strictly within 4.5 V to 5.5 V supply range, supports TTL-level input thresholds, and delivers VOH ≥ 3.8 V and VOL ≤ 0.44 V under 8 mA load. Its latch-up immunity exceeds 250 mA per JESD 17, and it features 14 pF typical power dissipation capacitance for low dynamic power consumption.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - defines valid operating window; outside this range risks functional failure or damage |
| Input Thresholds | VIH = 2 V, VIL = 0.8 V - ensures reliable recognition of standard TTL logic levels |
| Output Drive | ±8 mA - supports direct interface to standard 5 V logic loads without external buffering |
| Propagation Delay | 3.8–6.5 ns (CL = 15 pF) - determines maximum data rate in synchronous bus applications |
| Power Dissipation Cap. | 14 pF - enables accurate dynamic power estimation at 1 MHz switching frequency |
| Thermal Resistance | θJA = 88.3 °C/W - informs thermal design margin for continuous operation at 85 °C ambient |
| Operating Temperature | –40 °C to +85 °C - qualifies for industrial-grade embedded systems deployment |
Pinout & Package
SN74AHCT125BQAR uses a 14-pin WQFN (BQA) package with wettable flanks, 3.5 mm × 3.5 mm body, 0.5 mm pitch, and exposed thermal pad. Pin 1 marked by top-side dot; pin numbering follows counter-clockwise sequence from top-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 OE | Active-low enable for Channel 1 | Drives Y1 high-impedance when HIGH; enables A1→Y1 pass-through when LOW |
| 2 A1 | Input for Channel 1 | Accepts TTL/CMOS logic; must be terminated to VCC or GND if unused |
| 3 Y1 | Output for Channel 1 | Non-inverting buffered output; high-Z when 1OE = HIGH |
| 4 OE | Active-low enable for Channel 2 | Independent control allows selective channel activation without affecting others |
| 5 A2 | Input for Channel 2 | Electrically identical to A1; no internal coupling between channels |
| 6 Y2 | Output for Channel 2 | Drives load only when 2OE = LOW; otherwise presents >10⁹ Ω impedance |
| 7 GND | Ground reference | Primary return path for all I/O and supply currents; requires low-inductance PCB connection |
| 8 VCC | Positive supply | Must be bypassed with 0.1 µF capacitor placed adjacent to pin for noise suppression |
| 9 A3 | Input for Channel 3 | Same electrical specs as A1/A2; supports independent signal conditioning |
| 10 3OE | Active-low enable for Channel 3 | Enables concurrent or staggered channel enable timing across all four gates |
| 11 Y3 | Output for Channel 3 | Valid output only when 3OE = LOW; otherwise electrically disconnected from bus |
| 12 A4 | Input for Channel 4 | Final input; shares same VIH/VIL and Ci = 10 pF characteristics as other inputs |
| 13 4OE | Active-low enable for Channel 4 | Allows full quad-channel isolation or partial enable for mixed-signal routing |
| 14 Y4 | Output for Channel 4 | Delivers same VOH/VOL performance as Y1–Y3; supports parallel output driving |
Key Features
| Feature | Design Value |
|---|---|
| TTL-compatible inputs | Accepts 0.8 V / 2 V thresholds - eliminates need for level-shifting when interfacing legacy TTL systems |
| Independent 3-state control | Four separate OE pins - enables per-channel bus arbitration and avoids contention in multi-master designs |
| High noise immunity | VOL(P) ≤ 0.8 V, VOH(V) ≥ 4.4 V - maintains robust logic margins under dynamic switching noise |
| Latch-up immunity | >250 mA per JESD 17 - ensures survivability in transient overcurrent events on PCB |
| Low input capacitance | Ci = 10 pF - minimizes loading on upstream drivers and preserves signal edge integrity |
Applications
| Industrial Bus Isolation | Microcontroller GPIO Expansion |
|---|---|
|
Use Scenario: Isolating multiple sensor data lines sharing a common I²C or SPI bus to prevent cross-talk and contention during fault conditions. IC Role / Device Role / Timing Role: Quad buffer acts as programmable signal gate; each OE pin controlled by MCU to selectively connect/disconnect sensors. Use Value: Enables hot-plug capability and fault containment without hardware redesign; leverages existing 5 V bus voltage. |
Use Scenario: Expanding limited GPIO count on an ARM Cortex-M0+ MCU to drive eight discrete LEDs and two push-button inputs. IC Role / Device Role / Timing Role: SN74AHCT125BQAR provides four buffered outputs for LEDs and repurposes its inputs as debounced switch interfaces via software-controlled OE toggling. Use Value: Reduces BOM count by eliminating discrete transistors and pull-up resistors; simplifies firmware logic for LED multiplexing. |
| Switch Debouncing | Noise-Immune Signal Conditioning |
|
Use Scenario: Cleaning mechanical switch bounce in a factory HMI panel where contact chatter causes false triggers in PLC input modules. IC Role / Device Role / Timing Role: One buffer channel accepts raw switch signal; OE held LOW while A input is sampled synchronously by MCU after RC filter settling. Use Value: Achieves sub-millisecond debounce using only passive RC + single gate - no timer resources or firmware overhead required. |
Use Scenario: Driving long PCB traces (>10 cm) from a high-speed microcontroller to an ADC clock input susceptible to ringing and ground bounce. IC Role / Device Role / Timing Role: SN74AHCT125BQAR buffers and reshapes the clock edge; its 3.8 ns tPLH ensures jitter < 100 ps at 10 MHz. Use Value: Eliminates need for series termination or ferrite beads; maintains clean 50% duty cycle into 15 pF load. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus buffer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC125AQPWRQ1 | 1.65–3.6 V supply range; lower drive (±24 mA); automotive AEC-Q100 qualified | Required for 3.3 V systems or automotive environments; not pin-compatible due to different VCC/GND pinout | Select when operating below 4.5 V or requiring automotive qualification; verify layout changes for pin mapping |
| 74AHC125BQ | Wider supply range (2–5.5 V); higher speed (tPD = 3.2 ns); same WQFN-14 package | Preferred for mixed-voltage systems or higher-frequency buses (≥25 MHz); identical pinout enables drop-in replacement | Use for 3.3 V or 5 V designs needing faster propagation; confirmed pin-to-pin compatible with SN74AHCT125BQAR |
Compared with SN74LVC125AQPWRQ1, SN74AHCT125BQAR offers guaranteed 5 V TTL compatibility and simpler power rail design; compared with 74AHC125BQ, it trades minor speed reduction for tighter input threshold control and broader noise margin in legacy 5 V systems.
Availability
SN74AHCT125BQAR is available at Aetrix Electronics and suitable for industrial bus isolation, microcontroller GPIO expansion, switch debouncing, and noise-immune signal conditioning requiring stable component supply across production lifecycles.
Supply support for SN74AHCT125BQAR 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 and embedded processing solutions, with over 90 years of innovation in precision logic, power management, and signal chain technologies.
The SN74AHCT125BQAR belongs to TI's AHCT logic family, engineered for seamless interoperability between TTL and CMOS systems in industrial control, instrumentation, and legacy-compatible digital subsystems.
FAQ
What is the recommended power supply bypassing for SN74AHCT125BQAR?
A 0.1 µF ceramic capacitor must be placed between VCC and GND pins as close as possible to the SN74AHCT125BQAR package. This minimizes high-frequency supply noise and prevents output instability. For systems with heavy switching loads, paralleling a 1 µF capacitor improves low-frequency decoupling. The exposed thermal pad should be soldered to a solid ground plane for optimal thermal and electrical performance.
Can SN74AHCT125BQAR operate at 3.3 V supply?
No, SN74AHCT125BQAR is not specified for 3.3 V operation. Its recommended operating conditions require VCC = 4.5 V to 5.5 V. At 3.3 V, input thresholds (VIH = 2 V, VIL = 0.8 V) may not be met reliably, and output drive strength degrades significantly. For 3.3 V systems, consider SN74LVC125A or 74AHC125 instead.
How should unused inputs be handled on SN74AHCT125BQAR?
All unused inputs on SN74AHCT125BQAR must be tied to either VCC or GND - never left floating. Floating inputs cause undefined logic states, increased ICC current, and potential oscillation. A 10 kΩ pull-up or pull-down resistor is recommended if the input may be reconfigured later; direct connection is acceptable for permanently unused pins.
Is SN74AHCT125BQAR pin-compatible with SN74AHCT125DR (SOIC-14)?
No - SN74AHCT125BQAR (WQFN-14) and SN74AHCT125DR (SOIC-14) share identical logic functionality and signal pin assignments (e.g., Pin 1 = 1OE, Pin 2 = 1A), but their physical pinouts differ: BQA has GND at Pin 7 and VCC at Pin 8, whereas SOIC places GND at Pin 7 and VCC at Pin 14. PCB layout redesign is required for substitution.
What is the maximum capacitive load SN74AHCT125BQAR can drive while meeting datasheet timing specs?
SN74AHCT125BQAR guarantees full switching specifications (tPLH, tPHL, tPZH, etc.) up to CL = 15 pF. At CL = 50 pF, propagation delays increase to 8.5 ns max but remain functional. Driving loads >50 pF is not recommended - it degrades edge rates, increases power consumption, and may violate setup/hold timing in synchronous systems.
SN74AHCT125BQAR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHCT
- Package/Case:
- 14-WFQFN Exposed Pad
- 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-WQFN (3x2.5)
SN74AHCT125BQAR FAQ
1.How can I place an order for SN74AHCT125BQAR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHCT125BQAR 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 SN74AHCT125BQAR reliable?
The price and inventory of SN74AHCT125BQAR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHCT125BQAR is usually 5 days.
3.What payment methods are accepted for SN74AHCT125BQAR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHCT125BQAR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHCT125BQAR?
SN74AHCT125BQAR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHCT125BQAR 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 SN74AHCT125BQAR?
For technical support, including SN74AHCT125BQAR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHCT125BQAR requirements.
6.How does Aetrix verify that SN74AHCT125BQAR is sourced from the original manufacturer or authorized distributors?
All SN74AHCT125BQAR 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 SN74AHCT125BQAR meets industry standards.
7.What is the process for return or replacement of SN74AHCT125BQAR?
All SN74AHCT125BQAR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHCT125BQAR, 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 SN74AHCT125BQAR part is unused and in its original packaging.
Return procedure for SN74AHCT125BQAR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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