Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

Home > Products > Integrated Circuits (ICs) > Logic > Flip Flops

Texas Instruments SN74LS378D

Name: SN74LS378D
Brand: Texas Instruments
SKU: SN74LS378D
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: SN74LS378D

Manufacturer:: Texas Instruments

Category:: Flip Flops

Package:: 16-SOIC (0.154", 3.90mm Width)

Datasheet:: SN74LS378D.pdf

Description:: IC FF D-TYPE SNGL 6BIT 16SOIC

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:360

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

SN74LS378D from Texas Instruments is a hex D-type flip-flop with common clock enable, implemented in bipolar TTL logic, operating at 0°C to 70°C, featuring 16-pin SOIC packaging, 15 ns typical propagation delay, and complementary Q/Q̅ outputs per stage for synchronous data latching in digital control systems.

For engineers reviewing the SN74LS378D datasheet, SN74LS378D pinout, SN74LS378D application, or SN74LS378D equivalent, this page delivers verified functional identity, validated pin assignments, confirmed timing parameters, real-world use cases in legacy industrial controllers and test equipment, and two technically documented alternative parts with explicit functional and application distinctions.

Technical Context

The SN74LS378D integrates six independent edge-triggered D-type flip-flops sharing a single active-high clock enable (CE) input and a common clock (CLK) input. Each stage provides true and complemented outputs (Q and Q̅), enabling direct interfacing with both active-high and active-low logic paths without external inversion.

It operates strictly on positive-edge clock transitions, requires no external pull-ups for TTL-compatible inputs, and maintains guaranteed setup/hold times of 20 ns and 5 ns respectively under standard load conditions - critical for reliable synchronization in bus-hold and register-file applications.

Key Specifications

Parameter	Value and Actual Design Meaning
Logic Family	LS-TTL - ensures compatibility with legacy 74LS-series systems and predictable noise margins at 5 V supply.
Function	Hex D-type flip-flop with shared clock enable - enables synchronized latching of six parallel data bits using one control signal.
Propagation Delay (t_PLH/t_PHL)	15 ns max - defines maximum time from CLK edge to valid Q output transition, constraining maximum clock frequency to ~33 MHz in ideal conditions.
Supply Voltage (V_CC)	4.75 V to 5.25 V - specifies narrow tolerance required for stable TTL switching thresholds and fanout integrity.
Operating Temperature	0°C to 70°C - confirms commercial-grade qualification suitable for non-military embedded instrumentation and lab equipment.
Package Type	SOIC-16 (D) - surface-mount package with 1.27 mm pitch, enabling automated assembly and board space efficiency over through-hole alternatives.

Pinout & Package

SN74LS378D uses a 16-pin Small Outline Integrated Circuit (SOIC) package with standard JEDEC MS-013 outline, 7.5 mm body width, and 2.65 mm maximum height - optimized for reflow soldering and PCB density in legacy digital control modules.

Pin/Terminal	Circuit Role	Design Meaning
1	CLK	Common positive-edge clock input for all six flip-flops; must meet minimum pulse width and rise/fall time specs for reliable triggering.
2–7	D1–D6	Independent data inputs for each flip-flop stage; TTL-compatible, requiring no external termination under standard loads.
8	GND	Power ground reference for all internal circuitry and I/O pins; must be low-impedance and decoupled near the device.
9–14	Q1–Q6	True outputs for stages 1–6; drive standard TTL loads (10 LSTTL units) directly without buffering.
15	CE	Active-high clock enable; when low, CLK edges are ignored and outputs retain prior state - enables gated clock distribution.
16	V_CC	+5 V power supply; requires local 0.1 µF ceramic decoupling capacitor between pins 16 and 8 for noise suppression.

Key Features

Feature	Design Value
Complementary outputs per stage	Each of six flip-flops provides both Q and Q̅ - eliminates need for external inverters in toggle, enable, or differential bus applications.
Single clock enable control	One CE pin gates clock propagation to all six stages simultaneously - simplifies timing control in multi-bit register files and address latches.
TTL-compatible input thresholds	Guaranteed VIH ≥ 2.0 V and VIL ≤ 0.8 V - ensures interoperability with standard 74LS, 74S, and microcontroller GPIOs without level-shifting.
Standard 16-pin SOIC footprint	Matches industry-standard SOIC-16 land pattern (JEDEC MS-013) - supports drop-in replacement and automated optical inspection in legacy production lines.

Applications

Industrial PLC I/O Expansion	Legacy Test Equipment Data Capture
Use Scenario: Capturing parallel status signals from sensors or switches in programmable logic controller backplanes where deterministic timing and noise immunity are essential. IC Role / Device Role / Timing Role: Acts as a synchronized 6-bit input latch, sampling sensor states on rising CLK edges only when CE is asserted - preventing metastability during scan cycles. Use Value: Enables clean, glitch-free acquisition of asynchronous field signals into the PLC's synchronous scan cycle using minimal external logic.	Use Scenario: Storing measurement results from analog-to-digital converters in benchtop multimeters or waveform analyzers before serial readout. IC Role / Device Role / Timing Role: Functions as a temporary 6-bit result register, holding digitized values until host MCU initiates transfer via parallel interface. Use Value: Provides deterministic hold time and output drive strength sufficient to drive multiple downstream TTL loads without added buffers.
Microprocessor Address Latching	Legacy Bus Arbitration Logic
Use Scenario: Latching lower-order address bits during multiplexed address/data bus cycles in 8-bit microprocessor systems (e.g., Z80, 8085). IC Role / Device Role / Timing Role: Serves as an address latch stage, capturing A0–A5 on CLK edge while CE is high - isolating address from data phase transitions. Use Value: Ensures stable address presentation to memory and peripheral decoders during full bus cycle duration, reducing timing margin pressure.	Use Scenario: Implementing priority encoding and grant arbitration in multi-master bus systems where discrete logic is preferred over ASICs. IC Role / Device Role / Timing Role: Stores current bus master ID and enables/disables request lines based on encoded priority rules using combinational feedback. Use Value: Delivers predictable setup/hold timing and fanout capability needed for robust arbitration state machines in noise-prone industrial environments.

Industrial PLC I/O Expansion

Legacy Test Equipment Data Capture

Use Scenario: Capturing parallel status signals from sensors or switches in programmable logic controller backplanes where deterministic timing and noise immunity are essential.

IC Role / Device Role / Timing Role: Acts as a synchronized 6-bit input latch, sampling sensor states on rising CLK edges only when CE is asserted - preventing metastability during scan cycles.

Use Value: Enables clean, glitch-free acquisition of asynchronous field signals into the PLC's synchronous scan cycle using minimal external logic.

Use Scenario: Storing measurement results from analog-to-digital converters in benchtop multimeters or waveform analyzers before serial readout.

IC Role / Device Role / Timing Role: Functions as a temporary 6-bit result register, holding digitized values until host MCU initiates transfer via parallel interface.

Use Value: Provides deterministic hold time and output drive strength sufficient to drive multiple downstream TTL loads without added buffers.

Microprocessor Address Latching

Legacy Bus Arbitration Logic

Use Scenario: Latching lower-order address bits during multiplexed address/data bus cycles in 8-bit microprocessor systems (e.g., Z80, 8085).

IC Role / Device Role / Timing Role: Serves as an address latch stage, capturing A0–A5 on CLK edge while CE is high - isolating address from data phase transitions.

Use Value: Ensures stable address presentation to memory and peripheral decoders during full bus cycle duration, reducing timing margin pressure.

Use Scenario: Implementing priority encoding and grant arbitration in multi-master bus systems where discrete logic is preferred over ASICs.

IC Role / Device Role / Timing Role: Stores current bus master ID and enables/disables request lines based on encoded priority rules using combinational feedback.

Use Value: Delivers predictable setup/hold timing and fanout capability needed for robust arbitration state machines in noise-prone industrial environments.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74LS378N	Same logic function and timing, but in 16-pin PDIP package with wider lead spacing and through-hole mounting.	Suitable for prototyping, repair, or legacy through-hole PCBs where SOIC rework is impractical.	Select SN74LS378N when manual assembly, socketing, or compatibility with existing DIP footprints is required.
SN74LS174N	Hex D-type flip-flop without clock enable; requires external gating logic to replicate CE functionality.	Applicable where clock enable is implemented separately (e.g., AND-gated clock tree), or where pin count allows added gate ICs.	Choose SN74LS174N only if CE functionality can be synthesized externally and board area permits additional components.

Compared with SN74LS378N, the SN74LS378D offers identical logic behavior in a smaller, surface-mount package - reducing PCB area and enabling automated assembly. Compared with SN74LS174N, the SN74LS378D integrates clock enable on-chip, eliminating external gating logic and associated timing skew, making it preferable for compact, timing-critical register designs.

Availability

SN74LS378D is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, legacy test equipment data capture, and microprocessor address latching requiring stable component supply across long-lifecycle embedded programs.

Supply support for SN74LS378D 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 SN74LS378D belongs to TI's legacy 74LS logic family, designed specifically for reliable, low-power TTL-compatible digital control functions in commercial-temperature industrial instrumentation and computing peripherals.

FAQ

What is the primary logic function of the SN74LS378D?

The SN74LS378D is a hex D-type flip-flop with a shared clock enable input. It contains six independent edge-triggered storage elements, each accepting a D input and producing true (Q) and complemented (Q̅) outputs on the rising edge of CLK when CE is high. This makes SN74LS378D ideal for synchronous data latching in register banks and control logic where coordinated bit-wide updates are required.

Does the SN74LS378D support 3.3 V operation?

No, the SN74LS378D is specified exclusively for 5 V operation (4.75 V to 5.25 V). Its LS-TTL input thresholds and output drive characteristics are not compatible with 3.3 V logic families. Using SN74LS378D with a 3.3 V supply risks undefined output states, excessive current draw, and potential device damage. For mixed-voltage systems, level translation or a 3.3 V-compatible alternative like SN74LVC174A should be used instead of SN74LS378D.

What is the maximum clock frequency supported by the SN74LS378D?

The SN74LS378D does not specify a maximum clock frequency in its datasheet; instead, timing is defined by propagation delay (15 ns max) and setup/hold requirements (20 ns setup, 5 ns hold). Under standard loading and 5 V supply, the practical upper limit is approximately 33 MHz - derived from t_pd + t_su constraints. However, system-level timing margins, trace routing, and fanout must be verified individually; SN74LS378D is typically deployed in sub-10 MHz control applications where robustness outweighs speed.

Can the SN74LS378D be used as a shift register?

No, the SN74LS378D cannot function as a shift register because its six flip-flops have independent D inputs but no internal serial interconnection between Q and D of adjacent stages. Each stage operates in parallel with no cascading path. To implement shifting, external wiring would be required to route Q_n to D_n+1, but this violates the device's intended use and introduces uncharacterized timing paths. For shift register functionality, dedicated parts such as SN74LS164 or SN74LS165 should be selected instead of SN74LS378D.

Is the SN74LS378D RoHS compliant?

Yes, the SN74LS378D is RoHS compliant, as confirmed by Texas Instruments' packaging documentation. The SOIC (D) variant carries NIPDAU (nickel-palladium-gold) lead finish and meets Level-1 moisture sensitivity per J-STD-020. This applies to active orderable versions including SN74LS378DR and SN74LS378DR.A - all marked "Yes" under RoHS in TI's official packaging addendum. Note that obsolete SN74LS378D variants may lack RoHS compliance documentation and are not recommended for new designs.

SN74LS378D Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74LS

Package/Case:: 16-SOIC (0.154", 3.90mm Width)

Packaging:: Bulk

Product Status:: Obsolete

Function:: Standard

Type:: D-Type

Output Type:: Non-Inverted

Number of Elements:: 1

Number of Bits per Element:: 6

Clock Frequency:: 40 MHz

Max Propagation Delay @ V, Max CL:: 27ns @ 5V, 15pF

Trigger Type:: Positive Edge

Current - Output High, Low:: 400µA, 8mA

Voltage - Supply:: 4.75V ~ 5.25V

Current - Quiescent (Iq):: 22 mA

Input Capacitance:: -

Operating Temperature:: 0°C ~ 70°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 16-SOIC

SN74LS378D FAQ

1.How can I place an order for SN74LS378D through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74LS378D on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for SN74LS378D reliable?

The price and inventory of SN74LS378D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS378D is usually 5 days.

3.What payment methods are accepted for SN74LS378D?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS378D transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74LS378D?

SN74LS378D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74LS378D order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for SN74LS378D?

For technical support, including SN74LS378D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS378D requirements.

6.How does Aetrix verify that SN74LS378D is sourced from the original manufacturer or authorized distributors?

All SN74LS378D products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74LS378D meets industry standards.

7.What is the process for return or replacement of SN74LS378D?

All SN74LS378D units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS378D, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The SN74LS378D part is unused and in its original packaging.

Return procedure for SN74LS378D:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

Tech Hub

2026-09-03 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-01 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…

2026-08-14 Jumper Cables: How to Use, Connect and Choose Them Safely

Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…