Texas Instruments SN74LS374NE4

Overview

SN74LS374NE4 from Texas Instruments is an octal positive-edge-triggered D-type flip-flop with 3-state bus-driver outputs, designed for synchronous data latching in TTL-compatible digital systems. It features independent clock-enable control, high-impedance output disable (OC), and operates at 5 V with 24 mA sink capability per output. It is used in address/data bus buffering, I/O port expansion, and register file implementation in legacy industrial controllers and embedded instrumentation.

For engineers reviewing the SN74LS374NE4 datasheet, SN74LS374NE4 pinout, SN74LS374NE4 application, or SN74LS374NE4 equivalent, key selection criteria include its edge-triggered capture timing (20 ns setup, 5 ns hold), 35 MHz max clock frequency, 3-state output enable/disable latency (12–28 ns), and PDIP-20 package compatibility with through-hole PCB assembly and legacy test fixtures.

Technical Context

The SN74LS374NE4 implements eight independent D-type flip-flops synchronized to the rising edge of CLK, with asynchronous output control via low-active OC. Its internal latch structure ensures deterministic state capture only on clock transitions - not during level-sensitive windows - enabling reliable synchronization across parallel data paths.

All eight outputs share a common 3-state control (OC), allowing full bus isolation without affecting internal register state. The device uses standard TTL input thresholds (VIH = 2.0 V, VIL = 0.8 V) and drives loads up to 24 mA low / –2.6 mA high, supporting direct connection to terminated 50 Ω or capacitive bus lines without external pull-ups or buffers.

Key Specifications

Pinout & Package

SN74LS374NE4 is housed in a 20-pin plastic dual in-line package (PDIP-N), with 0.3-inch body width and through-hole mounting. Pin spacing follows JEDEC MS-001 standard.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS374N, SN74LS374NE4 offers identical performance with modern RoHS-compliant lead finish and traceable sourcing; versus SN74LS273N, it adds essential 3-state bus arbitration but omits asynchronous clear - making it superior for bus-oriented systems but unsuitable where global reset is mandatory.

Availability

SN74LS374NE4 is available at Aetrix Electronics and suitable for industrial control panels, legacy test equipment, and aerospace ground support systems requiring stable component supply and long-term obsolescence management.

Supply support for SN74LS374NE4 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 SN74LS374NE4 belongs to TI's legacy 74LS logic family, engineered for robust 5 V TTL system interfacing, bus loading, and synchronous data capture in cost-sensitive, high-reliability applications.

FAQ

What is the function of the OC pin on the SN74LS374NE4?

The OC (Output Control) pin on the SN74LS374NE4 is an active-low 3-state enable that places all eight Q outputs into high-impedance mode when asserted low. It has no effect on internal flip-flop states - data can still be clocked in via CLK while outputs remain isolated. This enables safe bus sharing in multi-master systems. The SN74LS374NE4 requires OC to be high for normal output operation.

Does the SN74LS374NE4 support asynchronous reset or clear functionality?

No, the SN74LS374NE4 does not include an asynchronous reset (CLR) or preset input. It is a pure edge-triggered D flip-flop with no provision for forced state initialization outside the normal CLK/D capture sequence. For applications requiring reset, external logic or a different part such as SN74LS273N must be used. The SN74LS374NE4 relies entirely on synchronous data loading.

What is the maximum clock frequency supported by the SN74LS374NE4?

The SN74LS374NE4 supports a maximum clock frequency of 35 MHz under standard test conditions (VCC = 5 V, TA = 25°C, RL = 667 Ω, CL = 45 pF). This rating assumes all outputs are loaded and timing margins meet datasheet minima (20 ns setup, 5 ns hold). At elevated temperatures or with heavier capacitive loads, derating is required to maintain reliable operation of the SN74LS374NE4.

Can the SN74LS374NE4 be used with 3.3 V logic systems?

No, the SN74LS374NE4 is strictly a 5 V TTL device with VIH = 2.0 V minimum and VIL = 0.8 V maximum - it is not 3.3 V tolerant. Driving its inputs from 3.3 V logic may result in marginal or failed high-level recognition, and applying 3.3 V to VCC violates its 4.75–5.25 V operating range. Interfacing with 3.3 V systems requires level-shifting circuitry or a 3.3 V–compatible alternative. The SN74LS374NE4 must operate at 5 V.

How does the SN74LS374NE4 differ from the SN74LS373N?

The SN74LS374NE4 is an edge-triggered D flip-flop (CLK↑ capture), whereas the SN74LS373N is a transparent latch (C high = pass-through, C low = latch). Their control logic, timing behavior, and use cases differ fundamentally: SN74LS374NE4 suits synchronous systems needing precise clock-aligned capture, while SN74LS373N fits level-sensitive gating. They share pinout and 3-state architecture but are not functionally interchangeable. The SN74LS374NE4 replaces SN74LS373N only with redesign.