Texas Instruments SN74HC125PWR

Overview

SN74HC125PWR from Texas Instruments is a quadruple 3-state buffer IC used for digital signal enablement and bus isolation in logic-level interfacing circuits. It operates across 2 V to 6 V supply, supports –40°C to +85°C ambient, delivers propagation delay as low as 11 ns at 6 V, and features balanced CMOS outputs capable of sourcing/sinking ±6 mA. It is commonly deployed in 4-bit data bus control applications where output disable capability is required.

For engineers reviewing the SN74HC125PWR datasheet, SN74HC125PWR pinout, SN74HC125PWR application, or SN74HC125PWR equivalent, key selection considerations include its 3-state output behavior, supply voltage flexibility (2–6 V), thermal performance in TSSOP-14 (R_θJA = 151.7°C/W), and compatibility with LSTTL fanout loads while consuming significantly less power.

Technical Context

The SN74HC125PWR implements four independent non-inverting buffers, each with an active-low 3-state output enable (OE) input. Each channel performs Y = A in positive logic, with no internal inversion or logic combination. Its CMOS inputs exhibit high impedance (≤±1 µA leakage at 6 V) and require fast edge rates (≤400 ns transition time at 6 V) to avoid shoot-through current.

Outputs are fully buffered CMOS with symmetrical drive strength: VOH ≥ 5.48 V and VOL ≤ 0.33 V at 6 V/7.8 mA, enabling reliable interfacing with both HC and HCT families. The device uses standard silicon-gate CMOS process technology and does not incorporate Schmitt-trigger inputs, clamp diodes beyond standard ESD protection, or internal pull resistors.

Key Specifications

Pinout & Package

TSSOP-14 package (5.00 mm × 4.40 mm body size), 14-pin thin shrink small-outline package with exposed pad not present; RoHS-compliant, NIPDAU lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 3-state buffer applications.

Compared with SN74HCT125PWR, the SN74HC125PWR provides broader supply flexibility and lower static power but requires external level shifting for pure 5 V TTL inputs; versus 74LVC125APW,118, it trades speed and 3.3 V optimization for universal 2–6 V operation and proven industrial temperature reliability.

Availability

SN74HC125PWR is available at Aetrix Electronics and suitable for industrial bus isolation, microcontroller I/O expansion, legacy TTL system interface, and test equipment signal gating requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74HC125PWR 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 company headquartered in Dallas, Texas, designing and manufacturing analog and embedded processing chips for industrial, automotive, and consumer applications.

The SN74HC125PWR belongs to TI's industry-standard 74HC logic family, engineered for low-power, high-noise-immunity digital interfacing in resource-constrained embedded systems where predictable 3-state behavior and wide supply tolerance are critical.

FAQ

What is the maximum capacitive load the SN74HC125PWR can reliably drive?

The SN74HC125PWR is characterized for optimal performance with ≤70 pF total load capacitance, including trace and receiver input capacitance. At 6 V supply, it maintains specified VOL ≤ 0.33 V and t_pd ≤ 31 ns up to 7.8 mA sink current. Driving larger loads may increase transition time and cause ringing; a series resistor is recommended if exceeding this limit. The SN74HC125PWR datasheet specifies CL = 50 pF and CL = 150 pF test conditions to illustrate performance boundaries.

Does the SN74HC125PWR have built-in ESD protection, and what are its ratings?

Yes, the SN74HC125PWR includes integrated ESD protection diodes on all pins. It is rated for ±2000 V per Human Body Model (HBM) and ±500 V per Charged-Device Model (CDM), compliant with JEDEC standards JS-001 and JESD22-C101. These ratings apply under standard handling conditions; proper ESD-safe practices (grounded workstations, ionizers, conductive packaging) remain essential during assembly. The SN74HC125PWR absolute maximum ratings also define ±20 mA clamp current limits to prevent damage during transient events.

Can unused inputs on the SN74HC125PWR be left floating?

No, unused inputs on the SN74HC125PWR must never be left floating. CMOS inputs have high impedance and undefined voltage states when unconnected, which can cause excessive current draw, logic instability, or device malfunction. Each unused input should be terminated to either VCC or GND using a direct connection or a pull-up/pull-down resistor (e.g., 10 kΩ). The SN74HC125PWR function table confirms that OE and A inputs directly control output state; floating OE pins may inadvertently enable or disable channels unpredictably.

What is the thermal resistance (RθJA) of the SN74HC125PWR in its TSSOP-14 package?

For the SN74HC125PWR in TSSOP-14 (PW) package, the junction-to-ambient thermal resistance RθJA is 151.7°C/W under standard JEDEC test conditions (1s pulse, no copper pour). This value assumes a 1-inch² 2-oz copper pad on a single-layer board. Real-world PCB layout - especially use of internal ground/power planes and thermal vias - can reduce effective RθJA by 20–40%. The SN74HC125PWR maximum junction temperature remains 150°C; at 6 V/7.8 mA worst-case loading, power dissipation stays well below thermal limits even in compact enclosures.

Is the SN74HC125PWR pin-compatible with other 74HC125 variants like SN74HC125DR or SN74HC125DBR?

Yes, the SN74HC125PWR is functionally and pinout-compatible with all 14-pin 74HC125 variants (e.g., SOIC SN74HC125DR, SSOP SN74HC125DBR), sharing identical pin numbering, signal assignments, and electrical behavior. Differences lie solely in package type (TSSOP vs. SOIC vs. SSOP), thermal metrics, and moisture sensitivity level. No PCB redesign is needed when substituting SN74HC125PWR for another 14-pin variant, provided footprint and soldering profile accommodate TSSOP-14 dimensions (5.00 mm × 4.40 mm) and fine-pitch leads.