Texas Instruments SN74F378DR

Overview

SN74F378DR from Texas Instruments is a positive-edge-triggered 6-bit D-type flip-flop with common clock enable (CLKEN), designed for synchronous data latching in digital logic systems. It operates at 5 V, supports up to 110 MHz clock frequency, features 20 mA low-level output drive, and is rated for 0°C to 70°C industrial temperature range. It is used in buffer/storage registers and pattern generators.

For engineers reviewing the SN74F378DR datasheet, SN74F378DR pinout, SN74F378DR application, or SN74F378DR equivalent, key selection criteria include clock enable architecture, single-rail Q outputs, SOIC-16 package compatibility, TTL-level input thresholds (VIL = 0.8 V, VIH = 2 V), and guaranteed 110 MHz maximum clock frequency across temperature.

Technical Context

The SN74F378DR implements six independent D-type flip-flops sharing one CLKEN input and one CLK input, with no common clear-distinguishing it from SN74F174. Each flip-flop transfers D-input data to Q-output on the positive-going edge of CLK only when CLKEN is low.

It uses standard TTL-compatible input thresholds and output drive capability (IOL = 20 mA, IOH = −1 mA), with propagation delays tPLH/tPHL ≤ 6.7 ns (max) at VCC = 4.5–5.5 V and CL = 50 pF. Setup time varies with CLKEN state (5 ns when CLKEN low, 3.5 ns when high).

Key Specifications

Pinout & Package

SN74F378DR is packaged in a 16-pin SOIC (D package), 300-mil width, with standard pin spacing and gull-wing leads compatible with automated SMT assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74F378DR, SN74F174N adds reset capability at the cost of enable flexibility, while SN74ALS378AN trades speed for lower power and enhanced noise margin-making each alternative appropriate only under specific design constraints rather than as drop-in replacements.

Availability

SN74F378DR is available at Aetrix Electronics and suitable for buffer/register design, pattern generation, and synchronous control logic requiring stable component supply in legacy 5-V TTL systems.

Supply support for SN74F378DR 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 with broad industrial and automotive reach.

The SN74F378DR belongs to TI's 74F TTL logic family, engineered for high-speed, 5-V digital systems where compatibility with legacy TTL interfaces and predictable timing behavior are essential.

FAQ

What is the function of the CLKEN pin on the SN74F378DR?

The CLKEN pin on the SN74F378DR is an active-low clock enable input that gates the clock signal to all six D-type flip-flops. When CLKEN is high, the flip-flops ignore CLK edges and retain their current Q outputs. Only when CLKEN is low does a positive-going CLK edge transfer data from D inputs to corresponding Q outputs. This allows synchronous, group-wise data capture without individual enable lines, and differentiates the SN74F378DR from variants like SN74F174 that use a common clear instead.

Does the SN74F378DR have a reset or clear function?

No, the SN74F378DR does not include an asynchronous or synchronous reset/clear input. Unlike the SN74F174, which features a common clear (CLR) pin, the SN74F378DR relies solely on clocked data loading via CLK and CLKEN. To initialize all outputs to a known state, external circuitry (e.g., pull-down resistors on D inputs combined with a controlled clock pulse) must be used. This absence of CLR is a deliberate design choice to prioritize enable-controlled operation over hard reset capability in the SN74F378DR.

What is the maximum clock frequency supported by the SN74F378DR?

SN74F378DR supports a maximum clock frequency of 110 MHz under recommended operating conditions (VCC = 4.5 V to 5.5 V, TA = 0°C to 70°C). This value is guaranteed across temperature and voltage extremes, with timing verified using CL = 50 pF and RL = 500 Ω loads. At 25°C and VCC = 5 V, typical performance reaches 125 MHz, but system design must adhere to the 110 MHz limit for full-spec compliance. The SN74F378DR's speed makes it suitable for high-throughput register and pattern-generation tasks in legacy TTL-based systems.

Can the SN74F378DR operate from a 3.3-V supply?

No, the SN74F378DR cannot operate reliably from a 3.3-V supply. Its recommended operating supply voltage is strictly 4.5 V to 5.5 V, and absolute maximum ratings specify −0.5 V to 7 V-however, functional operation below 4.5 V is not characterized or guaranteed. Input thresholds (VIH = 2 V, VIL = 0.8 V) and output drive (VOH ≥ 2.5 V at IOL = 20 mA) are specified only within the 5-V range. Using 3.3 V risks marginal or failed logic transitions, undefined timing, and potential damage due to improper biasing of internal TTL circuitry. For 3.3-V systems, consider modern CMOS alternatives such as SN74LVC374A.

Is the SN74F378DR pin-compatible with SN74F174 or SN74ALS378A?

The SN74F378DR is pin-compatible with both SN74F174N and SN74ALS378AN in the 16-pin DIP and SOIC packages (D/N drawings), sharing identical pinouts for VCC, GND, CLK, CLKEN/CLR, and all D/Q signals. However, functional differences exist: SN74F174N substitutes CLKEN with CLR on Pin 1, and SN74ALS378AN retains CLKEN but exhibits different AC characteristics (e.g., 60 MHz max clock). Thus, while physical replacement is possible, electrical and timing behavior differs-requiring validation of enable/reset logic and timing margins before substitution in existing designs using SN74F378DR.