Texas Instruments SN74S374DW

Overview

SN74S374DW from Texas Instruments is an octal edge-triggered D-type flip-flop with 3-state bus-driving outputs, clock-enable input with hysteresis for noise rejection, and P-N-P inputs to reduce DC loading on data lines. It operates at 5 V, supports up to 100 MHz clock frequency (RL = 280 Ω, CL = 15 pF), and features 8-bit parallel data latching synchronized on the positive clock edge - used in bus-organized systems for I/O port expansion and bidirectional bus control.

For engineers reviewing the SN74S374DW datasheet, SN74S374DW pinout, SN74S374DW application, or SN74S374DW equivalent, this device is selected for high-speed digital interface buffering where precise timing control, bus isolation via 3-state outputs, and robust noise immunity at clock/enable inputs are required in industrial and legacy computing designs.

Technical Context

The SN74S374DW implements eight independent positive-edge-triggered D-type flip-flops with synchronous latch behavior: Q outputs update only on the rising edge of CLK, retaining state otherwise. Its buffered OC (output control) input places all eight outputs simultaneously into high-impedance mode without affecting internal register operation - enabling dynamic bus sharing.

Input hysteresis on CLK and OC pins improves ac/dc noise rejection by ~400 mV versus standard TTL, while P-N-P input structure reduces input current draw (IIL = –250 µA max) and minimizes loading on upstream drivers. The device uses bipolar Schottky (S-series) technology for higher speed and lower propagation delay than LS variants.

Key Specifications

Pinout & Package

SN74S374DW is housed in a 20-pin SOIC (DW) package with 0.300-inch body width and standard gull-wing leads. Pin numbering follows JEDEC MS-013, with GND at pin 10 and VCC at pin 20.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS374DW and SN74ACT374DW, the SN74S374DW delivers superior noise immunity via hysteresis, faster timing (100 MHz vs 50 MHz/75 MHz), and lower input loading - making it the preferred choice for robust, high-speed TTL bus interfacing where signal integrity is compromised.

Availability

SN74S374DW is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, legacy computer bus interface, and automated test fixture data capture requiring stable component supply across long-lifecycle embedded programs.

Supply support for SN74S374DW 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 solutions for industrial, automotive, and communications markets.

The SN74S374DW belongs to TI's legacy TTL logic portfolio, designed specifically for high-speed, noise-resilient digital interfacing in bus-organized systems where reliability and timing precision are critical.

FAQ

What is the primary function of the SN74S374DW in a digital system?

The SN74S374DW functions as an octal positive-edge-triggered D-type flip-flop with 3-state outputs. It captures and holds 8-bit parallel data on the rising edge of its CLK input, then drives or isolates that data onto a shared bus via its active-low OC control. This makes SN74S374DW ideal for synchronous I/O buffering, register file implementation, and bus arbitration in TTL-based systems.

Does the SN74S374DW support true bidirectional data flow?

No, the SN74S374DW is unidirectional: it latches data from D inputs to Q outputs on CLK↑ and provides 3-state output control via OC, but does not support automatic direction sensing or internal data path reversal. For bidirectional bus driving, SN74S374DW must be paired with complementary devices like SN74S245 or used in master-slave configurations - unlike transceivers, SN74S374DW itself only drives Q from D.

What is the significance of hysteresis on the CLK and OC inputs of the SN74S374DW?

Hysteresis on CLK and OC inputs provides ~400 mV noise margin, meaning the input threshold rises after a low-to-high transition and falls after a high-to-low transition. This prevents multiple unintended toggles from slow-rising edges or EMI-induced voltage fluctuations - a key reliability feature for SN74S374DW in industrial control cabinets or electrically noisy test benches where signal integrity cannot be guaranteed.

Can the SN74S374DW operate reliably at 5.5 V supply?

Yes, the SN74S374DW is rated for VCC = 4.5 V to 5.5 V per its recommended operating conditions. At 5.5 V, parameters such as VOH (min 2.4 V), VOL (max 0.5 V), and fmax remain within specification, though ICC increases to 180 mA (outputs high). Designers should ensure adequate thermal management and use proper decoupling, as SN74S374DW's SOIC-DW package has θJA = 58°C/W.

How does the P-N-P input structure of the SN74S374DW improve system design?

The P-N-P input structure reduces low-level input current (IIL = –250 µA max) compared to standard TTL inputs (–0.4 mA for LS), significantly lowering DC loading on upstream drivers. This allows SN74S374DW to interface directly with high-impedance sources - such as certain DAC outputs or sensor buffers - without signal degradation or excessive fan-out limitations, enhancing compatibility in mixed-signal subsystems.