onsemi 74ACT174SC

Overview

74ACT174SC from Fairchild Semiconductor is a hex D-type edge-triggered flip-flop with master reset, designed as a 6-bit synchronous storage register. It operates at 4.5–5.5 V, supports 140 MHz max clock frequency, features TTL-compatible inputs, and delivers ±24 mA output drive. It is used in digital control logic, address latching, and data buffering where simultaneous reset and precise edge-triggered capture are required.

For engineers reviewing the 74ACT174SC datasheet, pinout, applications, or equivalent options, this page provides verified functional role, SOIC-16 package mapping, AC/ACT family timing boundaries, and validated alternatives for industrial logic design and legacy system replacement.

Technical Context

The 74ACT174SC implements six independent D-type flip-flops sharing a common clock (CP) and active-low master reset (MR), triggered on LOW-to-HIGH CP transitions. All outputs (Q0–Q5) reflect D-input states after each valid clock edge, while MR forces all Q outputs LOW regardless of CP or D state.

It belongs to the ACT logic family, guaranteeing TTL-compatible input thresholds (VIH = 2.0 V min, VIL = 0.8 V max at VCC = 5.5 V), 140 MHz maximum clock frequency over −40°C to +85°C, and propagation delays as low as 1.5 ns (tPLH/tPHL typ at VCC = 5.0 V, CL = 50 pF).

Key Specifications

Pinout & Package

74ACT174SC is housed in a 16-lead Small Outline Integrated Circuit (SOIC), JEDEC MS-012, 0.150" narrow body package (Package Number M16A).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT174N and 74VHC174M, the 74ACT174SC offers optimal balance of speed, drive strength, and SOIC-16 surface-mount compatibility for industrial control boards requiring reliable 5 V logic synchronization without layout changes.

Availability

74ACT174SC is available at Aetrix Electronics and suitable for industrial PLCs, digital test equipment, legacy system upgrades, and motor control logic requiring stable component supply and long-term obsolescence mitigation.

Supply support for 74ACT174SC 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

Fairchild Semiconductor was a leading designer of high-performance analog and logic ICs, acquired by ON Semiconductor in 2016; its legacy ACT/AC logic portfolio remains widely deployed in industrial infrastructure.

The 74ACT174SC belongs to Fairchild's ACT advanced CMOS logic family, engineered specifically for drop-in replacement of TTL in high-speed, noise-immune 5 V digital control systems.

FAQ

What is the recommended operating voltage range for the 74ACT174SC?

The 74ACT174SC is specified for 4.5 V to 5.5 V operation. Operation outside this range violates datasheet limits and may cause unreliable switching or increased ICC. The device does not support 3.3 V logic levels - use 74AC174 variants for dual-voltage designs. Always maintain VCC within ±5% tolerance using regulated supplies and local 0.1 µF ceramic decoupling per device.

Does the 74ACT174SC provide complementary (Q̅) outputs?

No, the 74ACT174SC provides only true outputs (Q0–Q5); it does not include inverted outputs. This simplifies routing in applications where only registered data is needed, such as address latches or control word storage. If both Q and Q̅ are required, designers must add external inverters or select alternative parts like 74ACT175 (which includes Q̅) - but note that 74ACT175 has different pinout and reset behavior.

How does the master reset (MR) function interact with the clock signal in the 74ACT174SC?

The MR input in the 74ACT174SC is asynchronous and active-low: asserting MR LOW forces all Q outputs LOW immediately, overriding any ongoing clock activity or D-input state. MR requires a minimum pulse width of 3.0 ns (guaranteed) at VCC = 5.0 V. Once MR returns HIGH, the next rising CP edge captures D-input data - no special recovery timing is needed beyond the standard tREC (0.5 ns min) from MR release to CP.

Can the 74ACT174SC be used in place of a 74LS174 in an existing design?

Yes, the 74ACT174SC is a direct functional and pinout-compatible replacement for 74LS174 in 5 V systems, offering higher speed (140 MHz vs. 30 MHz), lower power, and improved noise immunity. However, verify that board layout accommodates SOIC-16 dimensions and that output loading remains within ±24 mA limits - LS devices typically sink less current. No schematic changes are required, but decoupling should be reviewed for higher-frequency operation.

What is the minimum setup and hold time requirement for D inputs relative to CP in the 74ACT174SC?

At VCC = 5.0 V, the 74ACT174SC requires a minimum setup time (tS) of 1.5 ns and hold time (tH) of 2.0 ns for D inputs relative to the rising CP edge. These values are guaranteed over −40°C to +85°C. Violating either spec risks metastability or incorrect data capture. For robust timing closure, allocate ≥3 ns margin in FPGA- or microcontroller-driven clock domains where jitter or skew may exist.