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

Texas Instruments SN74LS377DWR

Name: SN74LS377DWR
Brand: Texas Instruments
SKU: SN74LS377DWR
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74LS377DWR

Manufacturer:: Texas Instruments

Category:: Flip Flops

Package:: 20-SOIC (0.295", 7.50mm Width)

Datasheet:: SN74LS377DWR.pdf

Description:: IC FF D-TYPE SNGL 8BIT 20SOIC

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Product details

Overview

SN74LS377DWR from Texas Instruments is an octal D-type flip-flop with clock enable, designed for synchronous data latching in TTL-level digital systems. It features 8 independent edge-triggered storage elements, a common clock input, and a single active-high enable control. Typical use includes address/data register buffering in microprocessor bus interfaces operating at ≤35 MHz.

For engineers reviewing the SN74LS377DWR datasheet, SN74LS377DWR pinout, SN74LS377DWR application, or SN74LS377DWR equivalent, key selection considerations include its 20-pin SOIC package, 0°C to 70°C commercial temperature range, TTL-compatible input thresholds, and guaranteed setup/hold timing relative to clock edge.

Technical Context

This device implements eight positive-edge-triggered D-type flip-flops with a shared clock (CLK) and a global asynchronous enable (G). Each flip-flop captures the logic state at its D input on the rising edge of CLK only when G is high; otherwise, outputs retain their previous state. No internal reset or preset is provided.

It belongs to the 74LS logic family and operates strictly within standard TTL voltage levels: V_CC = 4.75–5.25 V, input high ≥ 2.0 V, input low ≤ 0.8 V, output high ≥ 2.7 V (I_OH = –0.4 mA), output low ≤ 0.5 V (I_OL = 8 mA). Propagation delay t_PLH/t_PHL is specified at 25 ns max under typical load conditions.

Key Specifications

Parameter	Value and Actual Design Meaning
Logic Family	74LS (Low-power Schottky TTL) - ensures compatibility with legacy TTL bus systems and predictable noise margins.
Function	Octal D-type flip-flop with enable - provides eight parallel, edge-triggered data registers controlled by one clock and one enable signal.
Propagation Delay	25 ns max (t_PD) - supports reliable operation up to ~35 MHz clock frequency in buffered bus applications.
Supply Voltage	4.75 V to 5.25 V - requires tightly regulated +5 V rail; not tolerant of wider V_CC excursions.
Operating Temperature	0°C to 70°C - rated for commercial-grade environments only; unsuitable for extended industrial or automotive use.
Output Drive	8 mA sink / 0.4 mA source - sufficient to drive standard TTL inputs but insufficient for direct LED or relay loads without buffering.
Package	SOIC-20 (DW) - surface-mount, 0.300" wide body, RoHS-compliant NiPdAu lead finish, MSL Level-1.

Pinout & Package

SN74LS377DWR uses a 20-pin Small Outline Integrated Circuit (SOIC) package with 0.300" body width and 1.27 mm pitch. Pin 1 is located at the top-left corner with a beveled edge marker; pin numbering proceeds counterclockwise.

Pin/Terminal	Circuit Role	Design Meaning
1 (G)	Enable input	Active-high global enable: enables clocking of all eight flip-flops when high; no effect on stored data when low.
2–9 (D1–D8)	Data inputs	Independent asynchronous data inputs for each of the eight flip-flops; sampled on rising CLK edge if G = high.
10 (GND)	Ground	Reference return path for all internal circuitry and I/O; must be connected to system ground plane.
11–18 (Q1–Q8)	Outputs	Complementary registered outputs corresponding to D1–D8; retain state when G = low or CLK inactive.
19 (CLK)	Clock input	Positive-edge-triggered master clock; all eight flip-flops sample D inputs simultaneously on rising edge if G = high.
20 (V_CC)	Power supply	+5 V DC supply pin; requires local 0.1 µF ceramic decoupling capacitor placed within 5 mm of this pin.

Key Features

Feature	Design Value
Single-clock, single-enable architecture	Reduces control signal routing complexity in bus interface designs versus per-bit enable schemes.
No internal reset/preset	Eliminates unintended state clearing during power-up or noise events; initial state depends on power-on D input levels.
TTL-compatible input thresholds	Ensures interoperability with 74LS, 74S, and 74F logic families without level-shifting circuitry.
Guaranteed AC timing parameters	Specified setup (20 ns) and hold (5 ns) times enable deterministic timing closure in synchronous bus designs.
SOIC-20 RoHS-compliant packaging	Supports automated SMT assembly with standard reflow profiles (Level-1, 260°C peak); eliminates lead-based solder concerns.

Applications

Microprocessor Address Latching	Parallel Data Capture Interface
Use Scenario: Holding 8-bit address segments during multiplexed bus cycles in 8-bit microcontrollers like Z80 or 8085. IC Role / Device Role / Timing Role: Acts as an address latch that freezes A0–A7 signals after address valid assertion and before data transfer begins. Use Value: Eliminates need for discrete gating logic by providing synchronized, enable-controlled storage with minimal propagation skew across all bits.	Use Scenario: Capturing parallel sensor data (e.g., 8-channel ADC output) into a microcontroller's data bus. IC Role / Device Role / Timing Role: Serves as a synchronous input register, sampling external data on a system clock edge under software-controlled enable. Use Value: Provides deterministic setup/hold timing and eliminates metastability risk compared to direct GPIO sampling.
Bus Isolation Buffer	State-Holding Control Register
Use Scenario: Isolating two TTL bus segments where bidirectional flow is unnecessary but unidirectional data staging is required. IC Role / Device Role / Timing Role: Functions as a transparent, clock-gated buffer that prevents bus contention by holding last valid data until next update cycle. Use Value: Maintains stable bus states during arbitration gaps or processor wait states without requiring tri-state logic or additional control lines.	Use Scenario: Storing configuration bits (e.g., peripheral mode select, interrupt mask) in embedded controllers with infrequent updates. IC Role / Device Role / Timing Role: Implements a non-volatile shadow register updated only on explicit write pulses, retaining state between operations. Use Value: Delivers glitch-free, edge-triggered updates with no race conditions-unlike combinational latches vulnerable to enable timing jitter.

Microprocessor Address Latching

Parallel Data Capture Interface

Use Scenario: Holding 8-bit address segments during multiplexed bus cycles in 8-bit microcontrollers like Z80 or 8085.

IC Role / Device Role / Timing Role: Acts as an address latch that freezes A0–A7 signals after address valid assertion and before data transfer begins.

Use Value: Eliminates need for discrete gating logic by providing synchronized, enable-controlled storage with minimal propagation skew across all bits.

Use Scenario: Capturing parallel sensor data (e.g., 8-channel ADC output) into a microcontroller's data bus.

IC Role / Device Role / Timing Role: Serves as a synchronous input register, sampling external data on a system clock edge under software-controlled enable.

Use Value: Provides deterministic setup/hold timing and eliminates metastability risk compared to direct GPIO sampling.

Bus Isolation Buffer

State-Holding Control Register

Use Scenario: Isolating two TTL bus segments where bidirectional flow is unnecessary but unidirectional data staging is required.

IC Role / Device Role / Timing Role: Functions as a transparent, clock-gated buffer that prevents bus contention by holding last valid data until next update cycle.

Use Value: Maintains stable bus states during arbitration gaps or processor wait states without requiring tri-state logic or additional control lines.

Use Scenario: Storing configuration bits (e.g., peripheral mode select, interrupt mask) in embedded controllers with infrequent updates.

IC Role / Device Role / Timing Role: Implements a non-volatile shadow register updated only on explicit write pulses, retaining state between operations.

Use Value: Delivers glitch-free, edge-triggered updates with no race conditions-unlike combinational latches vulnerable to enable timing jitter.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74LS373N	Octal transparent latch (not edge-triggered); outputs follow inputs when LE is high, hold when LE goes low.	Better suited for address/data demultiplexing where latch-enable timing aligns with bus control signals rather than clock edges.	Select SN74LS373N when asynchronous capture or gated transparency is needed instead of strict clock-synchronous registration.
SN74LS574N	Octal D flip-flop with three-state outputs and separate output-enable (OE) control; identical clock/enable behavior to SN74LS377DWR.	Required when bus-sharing capability (e.g., connecting multiple devices to same data lines) is necessary alongside synchronous latching.	Choose SN74LS574N if tri-state outputs are essential; otherwise, SN74LS377DWR offers lower quiescent current and simpler enable logic.

Compared with SN74LS373N and SN74LS574N, SN74LS377DWR provides pure edge-triggered storage without transparency or output control-making it optimal for clock-synchronized register stages where deterministic timing and minimal pin count are priorities.

Availability

SN74LS377DWR is available at Aetrix Electronics and suitable for microprocessor bus interfacing, parallel data acquisition, industrial control I/O expansion, and legacy TTL system upgrades requiring stable component supply and long-term sourcing assurance.

Supply support for SN74LS377DWR 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 automotive portfolio coverage.

SN74LS377DWR belongs to TI's legacy 74LS logic family, engineered for reliability and interoperability in TTL-based digital systems deployed from the 1970s through modern retro-design and maintenance contexts.

FAQ

What is the maximum clock frequency supported by SN74LS377DWR?

The SN74LS377DWR has a maximum clock frequency of approximately 35 MHz, derived from its 25 ns maximum propagation delay and guaranteed setup/hold timing margins. This limit assumes nominal V_CC = 5 V, T_A = 25°C, and standard capacitive loading (CL = 15 pF). At temperature extremes or higher loads, derating is required.

Does SN74LS377DWR have built-in reset or preset functionality?

No, SN74LS377DWR does not include asynchronous reset (CLR) or preset (PRE) inputs. Its eight flip-flops retain their last latched state when the enable (G) signal is deasserted or the clock is inactive. Initial power-on state depends entirely on D-input levels present during first valid clock edge.

Can SN74LS377DWR directly drive LEDs or relays?

No, SN74LS377DWR cannot directly drive LEDs or relays. Its outputs provide only 8 mA sink current and 0.4 mA source current-sufficient for TTL logic loading but inadequate for typical indicator LEDs (requiring 5–20 mA) or relay coils (often >50 mA). External drivers such as ULN2003 or discrete transistors are required.

Is SN74LS377DWR pin-compatible with SN74LS374 or SN74LS574?

SN74LS377DWR is not pin-compatible with SN74LS374 or SN74LS574. While all three are 20-pin octal D flip-flops, SN74LS377DWR places its enable (G) on pin 1 and lacks output-enable (OE) pins. SN74LS574 uses pin 1 for OE and pin 11 for G, and SN74LS374 uses different pin assignments entirely. PCB layout changes are required for substitution.

What is the meaning of the part marking "(LS374, LS377)" on SN74LS377DWR devices?

The marking "(LS374, LS377)" on SN74LS377DWR indicates dual-marking used by Texas Instruments for die-sharing or wafer-level identification purposes. It confirms the device is functionally and electrically identical to the SN74LS377 specification-not a hybrid or variant-and should be treated as SN74LS377DWR in all design, qualification, and documentation contexts.

SN74LS377DWR Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74LS

Package/Case:: 20-SOIC (0.295", 7.50mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Active

Function:: Standard

Type:: D-Type

Output Type:: Non-Inverted

Number of Elements:: 1

Number of Bits per Element:: 8

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):: 28 mA

Input Capacitance:: -

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 20-SOIC

SN74LS377DWR FAQ

1.How can I place an order for SN74LS377DWR through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74LS377DWR 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 SN74LS377DWR reliable?

The price and inventory of SN74LS377DWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS377DWR is usually 5 days.

3.What payment methods are accepted for SN74LS377DWR?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS377DWR transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74LS377DWR?

SN74LS377DWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74LS377DWR 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 SN74LS377DWR?

For technical support, including SN74LS377DWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS377DWR requirements.

6.How does Aetrix verify that SN74LS377DWR is sourced from the original manufacturer or authorized distributors?

All SN74LS377DWR 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 SN74LS377DWR meets industry standards.

7.What is the process for return or replacement of SN74LS377DWR?

All SN74LS377DWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS377DWR, 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 SN74LS377DWR part is unused and in its original packaging.

Return procedure for SN74LS377DWR:

1.Submit a request within 90 days.

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

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