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

Texas Instruments SN74LS174D

Name: SN74LS174D
Brand: Texas Instruments
SKU: SN74LS174D
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: SN74LS174D

Manufacturer:: Texas Instruments

Category:: Flip Flops

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

Datasheet:: SN74LS174D.pdf

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

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Product details

Overview

SN74LS174D from Texas Instruments is a hex D-type flip-flop with asynchronous clear, implemented in low-power Schottky TTL logic. It contains six independent edge-triggered D flip-flops sharing a common clock and master clear, operating at V_CC = 5 V, t_pd = 25 ns (max), I_OH/I_OL = –0.4 mA / 8 mA, and supports 0°C to 70°C ambient operation. It is used in synchronous data latching, register file construction, and control-state storage in legacy industrial controllers.

For engineers reviewing the SN74LS174D datasheet, SN74LS174D pinout, SN74LS174D application, or SN74LS174D equivalent, this page delivers verified functional identity, SOIC-16 package mapping, timing parameters, real-world use cases, and two validated alternative parts for register-level design continuity.

Technical Context

The SN74LS174D implements six positive-edge-triggered D flip-flops with a shared asynchronous active-low clear (CLR̅) input. All flip-flops update on the rising edge of CLK, and CLR̅ forces Q outputs low regardless of clock or data state.

It belongs to the 74LS family and uses bipolar Schottky-clamped transistor logic for improved speed-power trade-off over standard 74TTL. Input thresholds are compatible with TTL voltage levels, and outputs drive standard TTL loads directly without pull-ups.

Key Specifications

Parameter	Value and Actual Design Meaning
Logic Family	74LS (Low-Power Schottky TTL) - enables direct interfacing with legacy TTL systems without level-shifting.
Function	Hex D-type flip-flop with common clock and asynchronous clear - provides six synchronized storage bits per package for compact register design.
Propagation Delay	25 ns max (CLK to Q) at V_CC = 5 V, T_A = 25°C - defines maximum clock-to-output timing margin in synchronous logic chains.
Output Drive	I_OH = –0.4 mA, I_OL = 8 mA - supports fan-out of up to 20 LS-TTL inputs or direct driving of small LEDs/relays via current-sinking.
Supply Voltage	V_CC = 4.75 V to 5.25 V - requires tightly regulated +5 V rail; not tolerant of wide-range or unregulated supplies.
Operating Temperature	0°C to +70°C - rated for commercial-grade environments only; unsuitable for extended industrial or automotive under-hood use.
Package	SOIC-16 (D package) - surface-mount footprint with 1.27 mm pitch; compatible with standard reflow profiles (MSL Level-1).

Pinout & Package

SN74LS174D is housed in a 16-pin Small Outline Integrated Circuit (SOIC) package with 1.27 mm lead pitch and gull-wing leads. The package is RoHS-compliant with NiPdAu lead finish and MSL Level-1 rating.

Pin/Terminal	Circuit Role	Design Meaning
1 (CLR̅)	Asynchronous clear input	Active-low global reset: forces all six Q outputs low immediately, overriding clock and D inputs.
2–7 (D1–D6)	Data inputs	Independent parallel data inputs for each of the six flip-flops; sampled on rising CLK edge.
8 (GND)	Ground reference	Power return path for logic and output drivers; must be low-impedance for noise immunity.
9–14 (Q1–Q6)	True outputs	Complementary registered outputs; no inverted (Q̅) outputs provided on this device.
15 (CLK)	Clock input	Positive-edge-triggered master clock; all six flip-flops update simultaneously on rising transition.
16 (V_CC)	Supply voltage	+5 V DC power supply; bypassing with 0.1 µF ceramic capacitor near pin is mandatory for stable operation.

Key Features

Feature	Design Value
Single-clock synchronization	One CLK input controls all six flip-flops, enabling deterministic, cycle-aligned state capture across multiple data paths.
Asynchronous global reset	CLR̅ resets all outputs independently of clock timing-critical for power-on initialization and fault recovery.
TTL-compatible I/O	Inputs accept standard TTL voltage thresholds; outputs drive LS-TTL loads directly-no external buffers required.
Low-power Schottky architecture	Reduces dynamic power vs. 74TTL while maintaining speed-typical I_CC = 24 mA at 5 MHz, enabling denser board layouts.
SOIC-16 packaging	Surface-mount form factor reduces PCB area vs. PDIP; supports automated assembly and higher component density.

Applications

Industrial PLC Register File	Legacy Test Equipment Control Logic
Use Scenario: Storing 6-bit configuration words (e.g., I/O enable masks, mode selections) in programmable logic controllers built before 2000. IC Role / Device Role / Timing Role: Acts as a synchronous latch bank, capturing control bits on system clock edges and holding state until next update cycle. Use Value: Provides deterministic, glitch-free bit storage with single-cycle load and hardware reset-reducing firmware overhead for state management.	Use Scenario: Capturing front-panel switch settings or calibration constants in benchtop oscilloscopes and logic analyzers from the 1980s–1990s. IC Role / Device Role / Timing Role: Serves as a static control register, holding user-selected instrument modes (e.g., trigger source, sweep rate) between power cycles. Use Value: Enables non-volatile behavior using external battery-backed RAM or manual switch persistence-no software bootload required.
Serial-to-Parallel Data Conversion	Digital Sequencer State Storage
Use Scenario: Converting serial shift-register output into parallel bus signals for address decoding or LED segment drivers in embedded instrumentation. IC Role / Device Role / Timing Role: Latches one byte of serially shifted data on final clock pulse, presenting full 6-bit parallel word to downstream logic. Use Value: Eliminates need for discrete latches or microcontroller GPIO expansion-reduces BOM count and timing complexity.	Use Scenario: Holding current step index in fixed-sequence digital timers or motor commutation controllers (e.g., stepper driver finite-state machines). IC Role / Device Role / Timing Role: Stores 6-bit counter value representing sequencer phase; updated synchronously with system clock and cleared on error or restart. Use Value: Guarantees atomic state updates-prevents metastability-induced missteps during clock domain crossings.

Industrial PLC Register File

Legacy Test Equipment Control Logic

Use Scenario: Storing 6-bit configuration words (e.g., I/O enable masks, mode selections) in programmable logic controllers built before 2000.

IC Role / Device Role / Timing Role: Acts as a synchronous latch bank, capturing control bits on system clock edges and holding state until next update cycle.

Use Value: Provides deterministic, glitch-free bit storage with single-cycle load and hardware reset-reducing firmware overhead for state management.

Use Scenario: Capturing front-panel switch settings or calibration constants in benchtop oscilloscopes and logic analyzers from the 1980s–1990s.

IC Role / Device Role / Timing Role: Serves as a static control register, holding user-selected instrument modes (e.g., trigger source, sweep rate) between power cycles.

Use Value: Enables non-volatile behavior using external battery-backed RAM or manual switch persistence-no software bootload required.

Serial-to-Parallel Data Conversion

Digital Sequencer State Storage

Use Scenario: Converting serial shift-register output into parallel bus signals for address decoding or LED segment drivers in embedded instrumentation.

IC Role / Device Role / Timing Role: Latches one byte of serially shifted data on final clock pulse, presenting full 6-bit parallel word to downstream logic.

Use Value: Eliminates need for discrete latches or microcontroller GPIO expansion-reduces BOM count and timing complexity.

Use Scenario: Holding current step index in fixed-sequence digital timers or motor commutation controllers (e.g., stepper driver finite-state machines).

IC Role / Device Role / Timing Role: Stores 6-bit counter value representing sequencer phase; updated synchronously with system clock and cleared on error or restart.

Use Value: Guarantees atomic state updates-prevents metastability-induced missteps during clock domain crossings.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74LS174N	Same logic function and electrical specs, but in 16-pin PDIP package with through-hole mounting and wider temperature range (0°C to 70°C same, but different thermal mass).	Preferred for prototyping, hand-soldered boards, or legacy repair where SOIC rework is impractical.	Select SN74LS174N when mechanical serviceability or breadboard compatibility outweighs board-space efficiency.
SN74LS174DR	Identical SOIC-16 function and specs; differs only in tape-and-reel packaging (2500 pcs/reel) and part marking ("LS174")-same die and parametric performance.	Designed for high-volume SMT production lines requiring automated pick-and-place feed.	Choose SN74LS174DR for volume manufacturing; SN74LS174D is obsolete but may remain in legacy inventory or small-batch sourcing.

Compared with SN74LS174N and SN74LS174DR, the SN74LS174D shares identical logic behavior and timing but is marked obsolete by TI-making SN74LS174DR the recommended production variant for new designs requiring SOIC-16, while SN74LS174N remains viable for through-hole builds.

Availability

SN74LS174D is available at Aetrix Electronics and suitable for legacy industrial controller upgrades, test equipment refurbishment, and educational lab kits requiring stable component supply with known timing behavior and TTL compatibility.

Supply support for SN74LS174D 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 ICs, embedded processors, and logic devices with broad industrial and aerospace heritage.

The SN74LS174D belongs to TI's classic 74LS logic family, designed specifically for reliable, low-power synchronous data storage in cost-sensitive, medium-speed digital systems of the 1970s–1990s.

FAQ

What is the primary function of the SN74LS174D?

The SN74LS174D is a hex D-type flip-flop with asynchronous clear, providing six independent edge-triggered storage elements in a single SOIC-16 package. Each flip-flop captures the logic state of its D input on the rising edge of CLK, and all outputs can be reset simultaneously via the active-low CLR̅ signal. Its function is strictly synchronous latching-not counting, shifting, or decoding.

Is the SN74LS174D still in active production?

No-the SN74LS174D is marked "Obsolete" in TI's official packaging documentation. However, SN74LS174DR (same SOIC-16 package, tape-and-reel format) remains active and functionally identical. For new designs, SN74LS174DR is the recommended replacement; SN74LS174D may be sourced from authorized distributors' legacy stock with full traceability.

Does the SN74LS174D provide complementary (Q̅) outputs?

No-the SN74LS174D provides only true (Q) outputs on pins 9–14. It does not include inverted (Q̅) outputs. If both Q and Q̅ are required per bit, external inverters or a dual-output variant like SN74LS175 (quad D flip-flop with Q and Q̅) must be used instead.

What is the maximum clock frequency supported by the SN74LS174D?

The SN74LS174D has no specified maximum clock frequency in its datasheet; instead, it specifies propagation delay (t_pd = 25 ns max) and setup/hold times (t_su = 20 ns, t_h = 5 ns). Based on these, a safe maximum toggle rate is ~15 MHz in typical conditions-but actual usable frequency depends on board layout, loading, and supply stability.

Can the SN74LS174D be used with 3.3 V logic systems?

No-the SN74LS174D is a 5 V-only TTL device. Its input thresholds and output voltage levels are defined for V_CC = 5 V ±5%, and it will not operate reliably-or may be damaged-when supplied with 3.3 V. Interfacing with 3.3 V systems requires level translation, such as TI's SN74LVC1T45 or discrete resistor-based solutions.

SN74LS174D 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:: Master Reset

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:: 30ns @ 5V, 15pF

Trigger Type:: Positive Edge

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

Voltage - Supply:: 4.75V ~ 5.25V

Current - Quiescent (Iq):: 26 mA

Input Capacitance:: -

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

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 16-SOIC

SN74LS174D FAQ

1.How can I place an order for SN74LS174D through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74LS174D 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 SN74LS174D reliable?

The price and inventory of SN74LS174D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS174D is usually 5 days.

3.What payment methods are accepted for SN74LS174D?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS174D transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74LS174D?

SN74LS174D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74LS174D 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 SN74LS174D?

For technical support, including SN74LS174D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS174D requirements.

6.How does Aetrix verify that SN74LS174D is sourced from the original manufacturer or authorized distributors?

All SN74LS174D 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 SN74LS174D meets industry standards.

7.What is the process for return or replacement of SN74LS174D?

All SN74LS174D units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS174D, 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 SN74LS174D part is unused and in its original packaging.

Return procedure for SN74LS174D:

1.Submit a request within 90 days.

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

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