Texas Instruments SN74AHC125RGYR

Overview

SN74AHC125RGYR from Texas Instruments is a quadruple bus buffer gate with independent 3-state outputs, operating across 2 V to 5.5 V supply range, supporting industrial temperature (–40°C to 125°C), delivering ±8 mA output drive at 5 V, and featuring four dedicated OE pins for per-channel enable control - used in programmable logic controllers and PoE interface isolation.

For engineers reviewing the SN74AHC125RGYR datasheet, SN74AHC125RGYR pinout, SN74AHC125RGYR application, or SN74AHC125RGYR equivalent, key selection criteria include VQFN-14 package thermal performance (RθJA = 87.1°C/W), 3.8 ns typical propagation delay at 5 V/15 pF, high-impedance state control via individual OE inputs, and compatibility with mixed-voltage logic interfacing in motor drive I/O expansion.

Technical Context

The SN74AHC125RGYR implements four independent CMOS buffer gates, each with active-low output enable (OE) controlling high-impedance or pass-through operation. Each channel isolates its A input from Y output when OE is high, and buffers A→Y when OE is low - enabling selective signal routing without contention.

Its AHC logic family ensures TTL-compatible input thresholds, rail-to-rail output swing, and low static current (ICC ≤ 40 µA over full temperature range). The VQFN-14 (RGY) package provides exposed thermal pad for enhanced power dissipation in space-constrained industrial PCBs.

Key Specifications

Pinout & Package

VQFN-14 (RGY) package: 3.5 mm × 3.5 mm body, 0.5 mm pitch, exposed thermal pad (EP) on underside for soldering to PCB ground plane - optimized for thermal management in compact industrial modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar bus buffer applications.

Compared with SN74LVC125APWR and 74AHC125D, the SN74AHC125RGYR uniquely balances wide voltage support (2–5.5 V), compact VQFN thermal performance, and industrial temperature rating - making it optimal for new designs requiring mixed-voltage interoperability and space efficiency.

Availability

SN74AHC125RGYR is available at Aetrix Electronics and suitable for programmable logic controllers, Power over Ethernet interfaces, and motor drive I/O expansion requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74AHC125RGYR 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 decades of experience in industrial-grade logic and interface solutions.

The SN74AHC125RGYR belongs to TI's AHC logic family - designed specifically for robust, low-power bus interfacing in harsh industrial environments where voltage flexibility, thermal resilience, and long-term reliability are critical.

FAQ

What is the recommended power supply decoupling for SN74AHC125RGYR?

Place a 0.1 µF ceramic capacitor between VCC (pin 14) and GND (pin 7), mounted as close as possible to the SN74AHC125RGYR package. For multi-VCC systems or noisy environments, add a 1 µF bulk capacitor nearby. The VQFN-14 package's exposed thermal pad must be soldered to a PCB ground plane to ensure effective thermal and electrical return path - this also improves high-frequency noise rejection for the SN74AHC125RGYR.

Can SN74AHC125RGYR interface between 3.3 V and 5 V logic domains?

Yes - the SN74AHC125RGYR supports 2 V to 5.5 V operation and accepts input voltages up to 5.5 V regardless of VCC. When powered at 5 V, its VIH minimum is 3.85 V, so a 3.3 V logic HIGH may not register reliably unless VCC is reduced to 3.3 V. For guaranteed 3.3 V → 5 V translation, operate SN74AHC125RGYR at 3.3 V and use external pull-ups on outputs if 5 V levels are required - the SN74AHC125RGYR itself does not perform active level shifting.

How should unused OE and input pins be handled on SN74AHC125RGYR?

All unused OE pins (1, 4, 10, 13) must be tied to VCC through a pull-up resistor (≥10 kΩ) to ensure outputs remain in high-impedance state during power-up and prevent bus contention. Unused A inputs (2, 5, 9, 12) must be tied to either VCC or GND - floating inputs cause increased ICC, erratic behavior, and potential latch-up. TI explicitly warns against leaving any digital input unconnected on the SN74AHC125RGYR.

What is the maximum capacitive load SN74AHC125RGYR can drive reliably?

The SN74AHC125RGYR is characterized up to 50 pF load capacitance, with tPLH/tPHL ≤ 8.5 ns at VCC = 5 V. Driving >50 pF increases propagation delay nonlinearly and may exceed output current limits (±8 mA). For heavier loads (e.g., long traces, multiple inputs), add series termination or use a buffer with higher drive strength. The SN74AHC125RGYR's 10 pF input capacitance ensures minimal loading on upstream drivers.

Does SN74AHC125RGYR support hot-swap or live-insertion scenarios?

The SN74AHC125RGYR has no built-in hot-swap protection, but its 3-state outputs and high-impedance default (when OE is high) make it suitable for controlled hot-swap implementations. To safely insert into a live bus, ensure OE pins are held high (via pull-ups) until power and control signals stabilize - TI recommends tying OE to VCC through ≥10 kΩ resistors. The SN74AHC125RGYR's ±1500 V HBM ESD rating further enhances robustness during handling and insertion.