Texas Instruments SN74AHC174NS

Overview

SN74AHC174NS from Texas Instruments is a hex D-type positive-edge-triggered flip-flop with asynchronous clear, designed for 2-V to 5.5-V operation. It contains six independent flip-flops with single-rail outputs, supports 110 MHz maximum clock frequency at 5 V, exhibits 4.1 ns typical propagation delay (CLK to Q), and meets JESD 17 latch-up immunity (>250 mA). It is used in synchronous buffer/register applications requiring deterministic edge-triggered storage.

For engineers reviewing the SN74AHC174NS datasheet, SN74AHC174NS pinout, SN74AHC174NS application, or SN74AHC174NS equivalent, key selection criteria include its 16-pin SOP-NS package, 5.5-V absolute max supply rating, ±8-mA output drive at 5 V, 0.5 ns hold time, and compatibility with AHC logic family voltage thresholds.

Technical Context

The SN74AHC174NS implements six identical D-type latches synchronized to the rising edge of CLK, with independent asynchronous active-low CLR inputs per stage. Each flip-flop transfers data from D to Q only on CLK's positive transition, provided setup (4.5 ns min at 5 V) and hold (0.5 ns min) timing constraints are met.

It uses CMOS AHC technology with rail-to-rail output swing, TTL-compatible input thresholds, and operates across –40°C to 85°C. Input clamping diodes and ESD protection (2000-V HBM, 200-V MM, 1000-V CDM) support robust board-level reliability without external protection components.

Key Specifications

Pinout & Package

SN74AHC174NS is housed in a 16-pin plastic small-outline package (SOP-NS), 5.3 mm wide, with 0.65 mm lead pitch and gull-wing leads. The package is RoHS-compliant, moisture-sensitive level 1, and rated for industrial temperature range (–40°C to 85°C).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHC174NS, SN74AHCT174N offers seamless integration into 5-V TTL environments via matched input thresholds, while SN74LV174AD trades clock speed for wider low-voltage support and higher output current-making each suitable for distinct supply and interface constraints.

Availability

SN74AHC174NS is available at Aetrix Electronics and suitable for industrial control panels, test equipment design, and embedded communication interfaces requiring stable component supply and long-term manufacturability.

Supply support for SN74AHC174NS 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 U.S.-based semiconductor company specializing in analog, embedded processing, and logic solutions, with decades of leadership in industry-standard logic families.

The SN74AHC174NS belongs to TI's advanced high-speed CMOS (AHC) logic portfolio, engineered for low-power, high-noise-immunity digital interfacing in industrial, computing, and communications infrastructure.

FAQ

What is the maximum clock frequency supported by SN74AHC174NS?

The SN74AHC174NS supports up to 110 MHz maximum clock frequency at VCC = 5 V and CL = 15 pF, as specified in the switching characteristics table. This value decreases to 80 MHz at 3.3 V and further drops under heavier capacitive loads (e.g., 50 pF). Designers must verify timing closure using actual board trace capacitance and worst-case voltage/temperature conditions before committing to 100+ MHz operation in the SN74AHC174NS.

Does SN74AHC174NS support mixed-voltage operation between 3.3 V and 5 V domains?

Yes, SN74AHC174NS operates across 2 V to 5.5 V, enabling direct connection between 3.3-V controllers and 5-V peripherals without level shifters. Its VIH threshold scales with VCC (e.g., 2.1 V at 3 V, 3.85 V at 5.5 V), ensuring reliable recognition of both 3.3-V high signals and 5-V logic levels. However, outputs swing rail-to-rail, so 3.3-V receivers must tolerate 5-V inputs unless current-limiting resistors or external clamping are applied.

Can SN74AHC174NS be used as a shift register without external feedback wiring?

No, SN74AHC174NS does not contain internal serial interconnects; it is a pure parallel-register IC with six independent D→Q paths. To implement a shift register, external PCB traces or wires must connect Qn to Dn+1 (e.g., 1Q→2D, 2Q→3D, etc.), and the unused D input (e.g., 1D) serves as serial data entry. This configuration is explicitly supported in TI's application guidance and matches standard 74-series shift register implementation practices.

What is the purpose of the NC pins on SN74AHC174NS?

SN74AHC174NS has no NC (No Connect) pins - all 16 pins are assigned functional roles (6×D, 6×Q, CLK, CLR, VCC, GND). The "NC" designation appears in the generic logic diagram footnote but does not apply to the NS package pinout. Pin 1 is CLR, Pin 2 is 1D, Pin 3 is 1Q, continuing through Pin 16 (VCC); no pin is internally unconnected or reserved. Misinterpretation may arise from other variants (e.g., D-package top view shows NC at Pins 3 and 12), but SN74AHC174NS uses full 16-pin utilization.

How does the asynchronous clear (CLR) function interact with clock timing in SN74AHC174NS?

In SN74AHC174NS, asserting CLR low forces all six Q outputs immediately to logic low, overriding any clock activity or data present at D inputs. This action occurs asynchronously - no CLK edge is required, and it takes effect within tPHL(CLR→Q) = 4.2 ns (typical at 5 V). When CLR returns high, the next CLK↑ captures the then-present D values; prior D states are not retained during CLR assertion. This behavior enables hard reset independent of clock domain timing.