Texas Instruments SN74AHC125RGYRG4

Overview

SN74AHC125RGYRG4 from Texas Instruments is a quadruple bus buffer gate with independent 3-state outputs, designed for logic-level translation and signal isolation in multi-rail digital systems. It operates from 2 V to 5.5 V, supports –40°C to +125°C industrial temperature range, delivers ±8 mA output drive at 5 V, and features four dedicated OE pins enabling per-channel enable/disable control - used in programmable logic controllers and PoE power management subsystems.

For engineers reviewing the SN74AHC125RGYRG4 datasheet, SN74AHC125RGYRG4 pinout, SN74AHC125RGYRG4 application, or SN74AHC125RGYRG4 equivalent, this page provides verified functional specifications, VQFN-14 package layout details, real-world timing behavior (e.g., 3.8 ns tPLH at 5 V), thermal resistance data (RθJA = 87.1 °C/W), and validated alternative options for bus buffering in space-constrained industrial designs.

Technical Context

The SN74AHC125RGYRG4 implements four independent CMOS buffer gates, each with active-low output-enable (OE) control. When OE is low, the A→Y path conducts with rail-to-rail logic compatibility; when OE is high, Y enters high-impedance state - critical for bidirectional bus arbitration and I/O expansion. Its AHC logic family ensures low static current (ICC ≤ 40 µA), fast propagation (tPLH/tPHL ≤ 6.5 ns @ 5 V, CL = 15 pF), and robust noise immunity (VIH/VIL thresholds scale with VCC).

Power-up safety requires OE tied to VCC via pullup resistor to guarantee high-Z state during supply ramp; minimum resistor value depends on driver sink capability. Input tolerance extends to –0.5 V to 7 V, supporting mixed-voltage interfacing without level shifters - a key differentiator versus standard HC or HCT variants.

Key Specifications

Pinout & Package

VQFN-14 (RGY) package: 3.5 mm × 3.5 mm body, 0.5 mm pitch, exposed thermal pad, lead-free NiPdAu finish, moisture sensitivity level 1 (260°C reflow compatible). Pin 1 marked by top-side dot; thermal pad soldered to PCB ground plane for optimal heat dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC125APWR and 74AHC125D, the SN74AHC125RGYRG4 uniquely balances ultra-compact VQFN packaging, 2–5.5 V operation, and industrial temperature support - making it optimal for next-generation edge controllers where board area, power versatility, and reliability are co-constrained.

Availability

SN74AHC125RGYRG4 is available at Aetrix Electronics and suitable for programmable logic controllers, Power over Ethernet (PoE) systems, and motor drive controls requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74AHC125RGYRG4 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 90 years of innovation in industrial, automotive, and communications markets.

The SN74AHC125RGYRG4 belongs to TI's AHC logic family - engineered for low-power, high-noise-immunity bus interfacing in harsh industrial environments where voltage flexibility and thermal resilience are non-negotiable.

FAQ

What is the recommended pullup resistor value for OE pins on the SN74AHC125RGYRG4?

The SN74AHC125RGYRG4 OE pins must be pulled to VCC to ensure high-impedance state at power-up. Minimum resistor value depends on the current-sinking capability of the driving GPIO - typically 10 kΩ suffices for standard microcontroller outputs. For weak-sink drivers (e.g., some FPGA I/O banks), values down to 4.7 kΩ may be needed to guarantee OE remains above VIH during brown-out conditions. Always verify with actual VCC ramp rate and driver spec sheet.

Can the SN74AHC125RGYRG4 interface 3.3 V logic with 5 V peripherals without level shifters?

Yes - the SN74AHC125RGYRG4 supports VCC = 3.3 V while accepting input voltages up to 7 V, allowing safe connection to 5 V peripherals. When VCC = 3.3 V, VIH = 2.1 V and VIL = 0.9 V, so 5 V logic HIGH signals exceed VIH marginally but remain valid. However, output swing is limited to 0–3.3 V, so downstream 5 V receivers require compatible input thresholds (e.g., TTL-compatible or 3.3 V tolerant).

How does the thermal performance of the SN74AHC125RGYRG4 compare to SOIC-packaged variants?

The SN74AHC125RGYRG4 in VQFN-14 has RθJA = 87.1 °C/W, significantly better than SOIC-14 (D package) at 124.5 °C/W. This 30% improvement stems from the exposed thermal pad soldered to PCB ground, enabling higher sustained output current in compact enclosures. At 100 mW dissipation, junction temperature rise is ~8.7°C vs. ~12.5°C for SOIC - critical for fanless motor control modules operating at +85°C ambient.

Is the SN74AHC125RGYRG4 suitable for hot-swap applications?

Yes - the SN74AHC125RGYRG4 tolerates input voltages down to –0.5 V and up to 7 V independent of VCC, making it robust against supply sequencing faults and transient overvoltages during hot-swap events. Its ±1500 V HBM ESD rating further protects against insertion-induced discharges. However, OE must remain asserted (high) until VCC stabilizes to prevent unintended output activation during ramp-up.

What is the maximum capacitive load the SN74AHC125RGYRG4 can drive while maintaining specified timing?

The SN74AHC125RGYRG4 is characterized for CL = 15 pF and 50 pF loads. At 5 V VCC, tPLH/tPHL increases from 3.8 ns (15 pF) to 5.3 ns (50 pF); at 3.3 V, it rises from 5.6 ns to 8.1 ns. Driving >50 pF risks violating setup/hold margins in high-speed interfaces. For heavier loads, add series termination or use dual-stage buffering - the SN74AHC125RGYRG4 itself should not drive >75 pF without timing validation.