Texas Instruments SN74S74NS

Overview

SN74S74NS from Texas Instruments is a dual D-type positive-edge-triggered flip-flop IC used for synchronous data storage and clocked logic control in TTL-based digital systems. It features two independent D flip-flops with complementary Q and Q̅ outputs, 14-pin PDIP package, operating supply voltage of 4.75 V to 5.25 V, and propagation delay of 4.5 ns typical at V_CC = 5 V. It is commonly deployed in address latching, state machine sequencing, and clock-domain synchronization in legacy industrial controllers.

For engineers reviewing the SN74S74NS datasheet, SN74S74NS pinout, SN74S74NS application, or SN74S74NS equivalent, key selection considerations include its TTL-compatible input thresholds, guaranteed setup/hold timing (t_su = 2.0 ns, t_h = 0.5 ns), direct replacement status for SN54S74J/SNJ54S74J in military-grade designs, and compatibility with 5-V-only logic families requiring fast edge-triggered storage.

Technical Context

The SN74S74NS implements two identical, independent D-type flip-flops, each with separate Data (D), Clock (CLK), Set (SD), and Reset (RD) inputs, plus true and complemented outputs (Q, Q̅). All inputs are TTL-compatible, and both flip-flops trigger on the rising edge of CLK with no internal gating between sections.

It uses bipolar Schottky TTL (S-series) technology, delivering higher speed and lower power-delay product than standard LS variants. Its guaranteed operation across –55°C to 125°C confirms qualification for extended-temperature military applications when packaged in CDIP or CFP variants - though SN74S74NS itself is the plastic DIP version rated for 0°C to 70°C.

Key Specifications

Pinout & Package

SN74S74NS is supplied in a 14-pin plastic dual in-line package (PDIP), 0.300-inch wide body, with standard through-hole mounting and JEDEC MS-001 compliant footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74S74N, SN74S74NS offers identical logic behavior and timing but optimized for high-volume automated assembly via tape-and-reel delivery; versus SNJ54S74J, it trades military qualification and temperature range for lower cost and commercial logistics support.

Availability

SN74S74NS is available at Aetrix Electronics and suitable for industrial automation, legacy test equipment refurbishment, and military-grade system sustainment requiring stable component supply and long-term traceability.

Supply support for SN74S74NS 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 founded in 1930, specializing in analog, embedded processing, and logic ICs with broad industrial and aerospace heritage.

The SN74S74NS belongs to TI's legacy 74S logic family, designed specifically for high-speed, 5-V TTL systems where propagation delay and fanout capability were prioritized over power efficiency.

FAQ

What is the maximum clock frequency supported by the SN74S74NS?

The SN74S74NS has a maximum toggle frequency of 100 MHz under typical conditions (V_CC = 5 V, T_A = 25°C), derived from its 4.5 ns propagation delay and 2.0 ns setup time. At elevated temperatures or reduced supply voltage, derating is required - consult TI's SDLS119 datasheet Figure 4 for frequency vs. temperature curves. The SN74S74NS does not specify a hard "maximum clock" limit but relies on meeting t_su/t_h and t_pd constraints in the target design.

Can SN74S74NS replace SN74LS74A in an existing design?

SN74S74NS can replace SN74LS74A only if the design accommodates higher supply current (I_CC ≈ 34 mA vs. 14 mA for LS) and tighter timing margins - its 4.5 ns t_pd is nearly 3× faster, but setup time is reduced to 2.0 ns (vs. 20 ns for LS), which may violate existing clock-to-data timing. Voltage thresholds and pinout are identical, but layout-level noise immunity and decoupling must be revalidated due to increased di/dt.

Does SN74S74NS support mixed-voltage interfacing, such as 3.3-V microcontrollers?

No, SN74S74NS does not support direct 3.3-V interfacing. Its inputs require TTL thresholds (V_IL ≤ 0.8 V, V_IH ≥ 2.0 V), and outputs swing fully to 5 V. Driving it from a 3.3-V device risks marginal high-level recognition; driving 3.3-V inputs with SN74S74NS outputs violates absolute maximum ratings. Level-shifting circuitry or a 5-V-tolerant buffer is required for interoperability.

What is the meaning of "NS" in SN74S74NS?

The "NS" suffix in SN74S74NS denotes Texas Instruments' packaging and packaging-related configuration: "N" indicates plastic dual in-line package (PDIP), and "S" specifies tape-and-reel delivery format (2000 units per reel). This distinguishes it from SN74S74N (same PDIP, tube packaging) and SN74S74D (SOIC package). The core logic function and electrical specs remain unchanged across these variants.

Is SN74S74NS RoHS-compliant?

Yes, SN74S74NS is RoHS-compliant per TI's documentation: it uses green molding compound (≤1000 ppm Br/Cl), NiPdAu lead finish, and meets EU RoHS Directive 2011/65/EU for all ten restricted substances. Its exemption status is "Green (RoHS & no Sb/Br)", confirmed in TI's Package Option Addendum dated 9-Oct-2020. No lead exemptions apply - it is fully lead-free.