STMicroelectronics 74AC174MTR

Overview

74AC174MTR from STMicroelectronics is a high-speed CMOS hex D-type flip-flop with asynchronous clear, operating from 2V to 6V supply, featuring 250MHz max clock frequency (at 5V), 24mA output drive, and 28% VCC noise immunity. It transfers data on the rising edge of CLOCK and resets all Q outputs low when CLEAR is asserted low - used in synchronous logic control, address latching, and register staging in industrial microcontroller interfaces.

For engineers reviewing the 74AC174MTR datasheet, 74AC174MTR pinout, 74AC174MTR application, or 74AC174MTR equivalent, key selection criteria include propagation delay matching (tPLH/tPHL ≈ 6–8 ns at 5V), 50Ω transmission line drive capability, symmetrical output impedance, latch-up immunity, and compatibility with legacy 74-series timing and control systems.

Technical Context

The 74AC174 implements six independent edge-triggered D flip-flops sharing a common CLOCK and asynchronous CLEAR input. Its sub-micron C2MOS process enables fast switching with balanced tPLH and tPHL delays and guaranteed operation across -55°C to +125°C.

All inputs tolerate 2kV ESD per HBM, and outputs deliver ±24mA into resistive loads while maintaining VOL ≤ 0.5V and VOH ≥ 3.7V at 4.5V supply - enabling direct interfacing with TTL, CMOS, and 50Ω transmission lines without external termination.

Key Specifications

Pinout & Package

74AC174MTR is supplied in a 16-pin SOIC (Small Outline Integrated Circuit) package with 1.27 mm pitch, JEDEC MS-012 compliant, body size 9.8 × 5.8 mm, and gull-wing leads suitable for reflow soldering.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar hex D-type flip-flop with clear applications.

Compared with SN74AC174N and 74VHC174M, the 74AC174MTR offers superior high-speed performance in SOIC packaging, broader voltage tolerance (2–6V), and stronger 50Ω line drive - making it optimal for industrial control and mixed-voltage embedded designs requiring compact surface-mount layout and robust timing.

Availability

74AC174MTR is available at Aetrix Electronics and suitable for industrial PLC I/O staging, microcontroller address latching, digital test equipment pattern storage, and legacy bus interface synchronization requiring stable component supply across extended temperature ranges.

Supply support for 74AC174MTR 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 automotive, industrial, and consumer markets.

The 74AC logic family targets high-speed, low-power, mixed-voltage digital interfacing - engineered for robustness in harsh environments and seamless integration with legacy TTL and modern CMOS systems.

FAQ

Is 74AC174MTR compatible with 74LS174 in pinout and function?

Yes - 74AC174MTR is pin- and function-compatible with 74LS174, including identical pin numbering, CLEAR-active-low behavior, and rising-edge clock triggering. However, it operates at higher speed (250 MHz vs. 30 MHz), draws less quiescent current (4 µA vs. 19 mA), and supports wider supply (2–6V vs. 4.75–5.25V), enabling direct replacement with performance gains.

What is the minimum pulse width required on CLEAR for reliable reset?

The minimum CLEAR pulse width is 5.0 ns at VCC = 5V (–40°C to +85°C). At full temperature range (–55°C to +125°C), it increases to 7.0 ns. This ensures complete metastability-free reset of all six flip-flops even under worst-case process/voltage/temperature corners.

Can 74AC174MTR drive a 50Ω transmission line directly without series termination?

Yes - its guaranteed ±24 mA output drive at VCC = 4.5V and symmetrical output impedance allow direct connection to 50Ω PCB traces. Measured VOL ≤ 0.5V and VOH ≥ 3.7V under 24mA load confirm compliance with 50Ω line driving requirements per JEDEC standards.

Does 74AC174MTR support partial power-down or I/O isolation when VCC = 0V?

No - the device lacks Ioff or power-down isolation features. When VCC = 0V, inputs and outputs may draw excessive current or behave unpredictably due to internal protection diodes. For hot-swap or partial-power systems, external isolation (e.g., series resistors or dedicated bus switches) is required.