STMicroelectronics 74ACT125TTR

Overview

74ACT125TTR from STMicroelectronics is a quad 3-state bus buffer IC designed for high-speed bidirectional data routing in TTL- and CMOS-compatible digital systems. It features 5 ns typical propagation delay at 5 V, ±24 mA symmetrical output drive, 4.5–5.5 V operating range, and 2 kV ESD protection. It is used in address/data bus isolation in industrial microcontroller peripherals.

For engineers reviewing the 74ACT125TTR datasheet, 74ACT125TTR pinout, 74ACT125TTR application, or 74ACT125TTR equivalent, key selection criteria include 3-state enable timing (tPZL/tPHZ ≤ 10 ns), transmission-line driving capability (50 Ω), VIH/VIL compatibility with legacy TTL, and TSSOP-14 thermal performance under continuous 24 mA switching loads.

Technical Context

The 74ACT125TTR implements four independent non-inverting buffers, each with active-low 3-state control (G1–G4). Each channel operates with matched tPLH ≈ tPHL propagation delays and symmetrical |IOH| = IOL ≥ 24 mA drive strength, enabling clean signal integrity on controlled-impedance PCB traces.

Its C2MOS sub-micron process delivers low ICC = 4 µA (max) quiescent current while maintaining TTL-compatible input thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V at VCC = 4.5 V) and rail-to-rail output swing (VOH ≥ 3.86 V at IOH = –24 mA, VOL ≤ 0.5 V at IOL = 24 mA).

Key Specifications

Pinout & Package

TSSOP-14 package: 4.9 × 6.4 mm body, 0.65 mm pitch, 1.2 mm height, lead-free, moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT125PW and 74VHC125FT, the 74ACT125TTR uniquely combines 50 Ω line driving, 5 ns speed, and industrial temperature support in a standard TSSOP-14, making it optimal for high-reliability 5 V bus isolation where signal integrity and layout simplicity are critical.

Availability

74ACT125TTR is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive body control modules, and medical diagnostic imaging interfaces requiring stable component supply across multi-year production cycles.

Supply support for 74ACT125TTR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, digital, and mixed-signal ICs for industrial, automotive, and consumer markets.

The 74ACT logic family targets high-speed, low-power 5 V digital interfacing-optimized for bus buffering, level translation, and signal conditioning in noise-sensitive embedded systems.

FAQ

What is the maximum output current per channel, and under what conditions is it guaranteed?

The 74ACT125TTR guarantees ±24 mA output current per channel when VOH ≥ 3.86 V (at VCC = 4.5 V, IOH = –24 mA) and VOL ≤ 0.5 V (at VCC = 5.5 V, IOL = 24 mA). This rating applies across the full operating temperature range (–55°C to +125°C) and ensures reliable 50 Ω transmission-line driving without external buffers.

Can the 74ACT125TTR operate reliably at 4.5 V supply with TTL-level inputs?

Yes. At VCC = 4.5 V, VIH is guaranteed ≥ 1.5 V (min) and VIL ≤ 0.8 V (max), fully satisfying standard TTL output voltage levels (VOH ≥ 2.4 V, VOL ≤ 0.4 V). The device maintains 5 ns typical propagation delay and 24 mA drive even at the lower supply limit.

Is the TSSOP-14 package RoHS-compliant and lead-free?

Yes. The 74ACT125TTR uses a lead-free, halogen-free TSSOP-14 package compliant with RoHS Directive 2011/65/EU and JEDEC J-STD-020 moisture sensitivity level 1. Reflow profile follows IPC/JEDEC J-STD-020D, with peak temperature ≤ 260°C.

How does the 3-state enable timing affect bus arbitration in multi-master systems?

tPZL and tPHZ are both ≤ 10 ns (max) across temperature, ensuring rapid, deterministic bus release. This allows tight turnaround windows (< 20 ns) between master transmissions-critical for synchronous protocols like IEEE 1149.1 JTAG or proprietary daisy-chained diagnostics buses.