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

Texas Instruments SN74LS273NE4

Name: SN74LS273NE4
Brand: Texas Instruments
SKU: SN74LS273NE4
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74LS273NE4

Manufacturer:: Texas Instruments

Category:: Flip Flops

Package:: 20-DIP (0.300", 7.62mm)

Datasheet:: SN74LS273NE4.pdf

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

Quantity:: RFQ Add To RFQ list

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Product details

Overview

SN74LS273NE4 from Texas Instruments is an octal D-type positive-edge-triggered flip-flop with asynchronous clear, implemented in low-power Schottky TTL logic. It features eight independent D inputs, eight Q outputs, a shared clock (CLK), and a direct-clear (CLR) input. Each flip-flop transfers data on the rising edge of CLK while CLR forces all Q outputs low regardless of clock state - used in synchronous register storage and pattern generation circuits.

For engineers reviewing the SN74LS273NE4 datasheet, SN74LS273NE4 pinout, SN74LS273NE4 application, or SN74LS273NE4 equivalent, this page delivers verified electrical specs (V_IL = 0.8 V, t_su = 20 ns, f_max = 40 MHz), PDIP-20 package mapping, functional pin roles, real-world use cases in legacy industrial control and test equipment, and two validated alternative parts with documented parameter differences.

Technical Context

This device implements eight independent D-type latches synchronized to a common positive-edge clock and controlled by a single active-low asynchronous clear. Its TTL-compatible inputs accept standard 5 V logic levels, and outputs drive standard TTL loads with I_OL = 8 mA and I_OH = –400 µA at V_CC = 5 V.

Propagation delays are tightly specified: t_PLH/t_PHL ≤ 27 ns (CL = 15 pF, R_L = 2 kΩ), and minimum pulse widths for CLK and CLR are both 20 ns. The device operates across 0°C to 70°C and draws only 17–27 mA typical supply current under full load.

Key Specifications

Parameter	Value and Actual Design Meaning
V_CC Range	4.75 V to 5.25 V - ensures stable operation within standard 5 V TTL supply tolerance.
Max Clock Frequency	30 MHz guaranteed, 40 MHz typical - supports high-speed synchronous register transfer in legacy digital systems.
Input Thresholds	V_IL = 0.8 V max, V_IH = 2.0 V min - compatible with standard TTL and LS-family logic interfaces.
Output Drive	I_OL = 8 mA, I_OH = –400 µA - sufficient to drive multiple TTL inputs or small LED indicators directly.
Propagation Delay	t_PLH/t_PHL ≤ 27 ns - enables precise timing alignment in multi-stage pipeline registers.
Power Dissipation	Typical 27 mA ICC at V_CC = 5.5 V - low static power for LS-series, critical in dense board layouts.
Operating Temperature	0°C to 70°C - qualified for commercial-grade embedded and instrumentation applications.

Pinout & Package

SN74LS273NE4 is housed in a 20-pin plastic dual in-line package (PDIP-N), with 0.3-inch body width and 0.1-inch lead pitch. Pin 1 is marked by a notch or dot; leads are tin-lead (NIPDAU) finish, RoHS-compliant.

Pin/Terminal	Circuit Role	Design Meaning
1	CLR	Active-low asynchronous clear - forces all Q outputs low immediately, overriding clock and data.
2–9	1D–8D	Eight independent D inputs - each feeds one flip-flop's data latch prior to clock edge.
10	GND	Ground reference - return path for all internal currents and output loads.
11–18	1Q–8Q	Eight complementary Q outputs - registered data appears here after positive CLK edge.
19	CLK	Positive-edge-triggered clock - sampling occurs only on rising transition; level-insensitive.
20	V_CC	+5 V supply - powers all internal TTL circuitry and output drivers.

Key Features

Feature	Design Value
Octal D-type architecture	Eight independent, edge-triggered storage elements in one IC - reduces board space vs. discrete flip-flops.
Asynchronous clear	Single-pin global reset - eliminates need for external gating logic to initialize register banks.
LS-TTL compatibility	Meets standard TTL voltage thresholds and fanout - interoperable with 74LS, 74S, and 74F families without level shifting.
Low power consumption	27 mA typical ICC - ~70% lower than original 74273, enabling higher density in power-constrained designs.
Rising-edge clock sensitivity	Triggering defined at voltage threshold, not transition rate - immune to slow-rising clock edges in noisy environments.

Applications

Industrial Control Register	Test Equipment Pattern Generator
Use Scenario: Storing parallel I/O states in programmable logic controllers (PLCs) for scan-cycle synchronization. IC Role / Device Role / Timing Role: Acts as an 8-bit synchronous latch bank, capturing sensor or actuator status on system clock edge. Use Value: Ensures deterministic timing between input sampling and output update, preventing metastability in cyclic control loops.	Use Scenario: Generating fixed test vectors for digital circuit validation in automated test equipment (ATE). IC Role / Device Role / Timing Role: Stores and sequences predefined bit patterns across eight channels using cascaded clocking. Use Value: Delivers repeatable, jitter-free stimulus waveforms with sub-30 ns timing resolution for high-accuracy fault detection.
Legacy Bus Interface Buffer	Digital Signal Processing Pipeline Stage
Use Scenario: Isolating and synchronizing data between mismatched bus domains (e.g., CPU address/data bus and peripheral controller). IC Role / Device Role / Timing Role: Functions as a transparent 8-bit register stage, aligning asynchronous writes to local clock domain. Use Value: Eliminates setup/hold violations during bus handshaking, enabling reliable communication with slower peripherals.	Use Scenario: Holding intermediate results in fixed-point FIR filter implementations on vintage DSP boards. IC Role / Device Role / Timing Role: Provides pipeline delay stages between arithmetic units, timed by master system clock. Use Value: Enables throughput improvement via instruction-level parallelism without requiring custom ASIC logic.

Industrial Control Register

Test Equipment Pattern Generator

Use Scenario: Storing parallel I/O states in programmable logic controllers (PLCs) for scan-cycle synchronization.

IC Role / Device Role / Timing Role: Acts as an 8-bit synchronous latch bank, capturing sensor or actuator status on system clock edge.

Use Value: Ensures deterministic timing between input sampling and output update, preventing metastability in cyclic control loops.

Use Scenario: Generating fixed test vectors for digital circuit validation in automated test equipment (ATE).

IC Role / Device Role / Timing Role: Stores and sequences predefined bit patterns across eight channels using cascaded clocking.

Use Value: Delivers repeatable, jitter-free stimulus waveforms with sub-30 ns timing resolution for high-accuracy fault detection.

Legacy Bus Interface Buffer

Digital Signal Processing Pipeline Stage

Use Scenario: Isolating and synchronizing data between mismatched bus domains (e.g., CPU address/data bus and peripheral controller).

IC Role / Device Role / Timing Role: Functions as a transparent 8-bit register stage, aligning asynchronous writes to local clock domain.

Use Value: Eliminates setup/hold violations during bus handshaking, enabling reliable communication with slower peripherals.

Use Scenario: Holding intermediate results in fixed-point FIR filter implementations on vintage DSP boards.

IC Role / Device Role / Timing Role: Provides pipeline delay stages between arithmetic units, timed by master system clock.

Use Value: Enables throughput improvement via instruction-level parallelism without requiring custom ASIC logic.

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
SN74LS374N	Tri-state outputs, separate OE control; identical timing and voltage specs.	Required when bus-sharing or bidirectional data routing is needed.	Select SN74LS374N if output contention management or multiplexed bus loading is required.
SN74HC273N	CMOS technology: V_CC = 2–6 V, I_OL = 4 mA, t_pd ≈ 25 ns, lower ICC (~4 µA).	Suitable for mixed-voltage systems or battery-powered designs where power is critical.	Choose SN74HC273N for wider supply range, lower static power, or 3.3 V compatibility - but verify noise margin with TTL inputs.

Compared with SN74LS273NE4, SN74LS374N adds output enable for bus isolation but requires additional control logic, while SN74HC273N offers CMOS efficiency and voltage flexibility at the cost of reduced drive strength and different input thresholds - both require layout and timing revalidation.

Availability

SN74LS273NE4 is available at Aetrix Electronics and suitable for industrial control systems, legacy test equipment, and digital signal processing pipelines requiring stable component supply and long-term obsolescence mitigation.

Supply support for SN74LS273NE4 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 and embedded processing technologies with broad industrial, automotive, and aerospace product lines.

SN74LS273NE4 belongs to TI's legacy 74LS logic family, designed specifically for reliable, low-power synchronous data storage in commercial-grade digital systems operating at 5 V.

FAQ

What is the maximum clock frequency supported by SN74LS273NE4?

The SN74LS273NE4 guarantees operation up to 30 MHz across its full temperature and voltage range, with typical performance reaching 40 MHz at V_CC = 5 V and T_A = 25°C. This makes SN74LS273NE4 suitable for high-speed register applications in legacy digital systems where timing margins must be maintained under worst-case conditions.

Does SN74LS273NE4 have tri-state outputs?

No, SN74LS273NE4 does not feature tri-state outputs - all eight Q outputs are push-pull and always driven high or low. For bus-oriented applications requiring output disable capability, consider SN74LS374N, which provides identical flip-flop functionality plus individual output-enable control.

What is the function of the CLR pin on SN74LS273NE4?

The CLR pin on SN74LS273NE4 is an active-low asynchronous clear input that forces all eight Q outputs low immediately, independent of the clock signal. This allows SN74LS273NE4 to be globally reset without waiting for a clock edge, making it ideal for system initialization and error recovery in synchronous logic designs.

Can SN74LS273NE4 operate at 3.3 V?

No, SN74LS273NE4 is specified only for 4.75 V to 5.25 V operation and is not rated for 3.3 V supply. Attempting to run SN74LS273NE4 at 3.3 V will result in undefined logic levels and unreliable switching. For 3.3 V systems, SN74HC273N is a functionally equivalent CMOS alternative with full 2–6 V support.

What package type is used for SN74LS273NE4?

SN74LS273NE4 uses a 20-pin plastic dual in-line package (PDIP-N), with 0.3-inch width, 0.1-inch lead pitch, and RoHS-compliant NIPDAU lead finish. This through-hole package is widely supported in legacy manufacturing and prototyping environments, and matches pinout and footprint of other 74LS-series 20-pin DIP devices.

SN74LS273NE4 Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 74LS

Package/Case:: 20-DIP (0.300", 7.62mm)

Packaging:: Tube

Product Status:: Active

Function:: Master Reset

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):: 27 mA

Input Capacitance:: -

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

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 20-PDIP

SN74LS273NE4 FAQ

1.How can I place an order for SN74LS273NE4 through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74LS273NE4 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 SN74LS273NE4 reliable?

The price and inventory of SN74LS273NE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS273NE4 is usually 5 days.

3.What payment methods are accepted for SN74LS273NE4?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS273NE4 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74LS273NE4?

SN74LS273NE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74LS273NE4 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 SN74LS273NE4?

For technical support, including SN74LS273NE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS273NE4 requirements.

6.How does Aetrix verify that SN74LS273NE4 is sourced from the original manufacturer or authorized distributors?

All SN74LS273NE4 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 SN74LS273NE4 meets industry standards.

7.What is the process for return or replacement of SN74LS273NE4?

All SN74LS273NE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS273NE4, 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 SN74LS273NE4 part is unused and in its original packaging.

Return procedure for SN74LS273NE4:

1.Submit a request within 90 days.

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

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