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

STMicroelectronics 74AC374B

Name: 74AC374B
Brand: STMicroelectronics
SKU: 74AC374B
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 74AC374B

Manufacturer:: STMicroelectronics

Category:: Flip Flops

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

Datasheet:: 74AC374B.pdf

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

Quantity:: RFQ Add To RFQ list

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Product details

Overview

74AC374B from STMicroelectronics is an advanced high-speed CMOS octal D-type flip-flop with 3-state non-inverting outputs, designed for synchronous data latching and bus interface control in digital systems. It features 8-bit parallel data storage, clocked on positive edge of CK, output enable (OE) control, 2V–6V operating voltage, 270MHz max clock frequency at 5V, and ±24mA symmetrical drive capability.

For engineers reviewing the 74AC374B datasheet, 74AC374B pinout, 74AC374B application, or 74AC374B equivalent, key selection considerations include its 3-state bus-driving capability, low 4µA quiescent current, 50Ω transmission line compatibility, balanced tPLH/tPHL propagation delays, and industrial temperature range support (−55°C to +125°C).

Technical Context

The 74AC374B implements eight independent D-type latches triggered by the rising edge of the clock (CK), with asynchronous 3-state output control via active-low OE. Its sub-micron C2MOS process enables high noise immunity (28% VCC) and latch-up robustness. All inputs and outputs include 2kV ESD protection.

It operates across a wide supply range (2V–6V), supports incident-wave switching on 50Ω transmission lines, and maintains symmetrical output impedance (|IOH| = IOL ≥ 24mA). Propagation delays are balanced (tPLH ≅ tPHL), and setup/hold times are specified down to −0.5ns/0.5ns at 5V.

Key Specifications

Parameter	Value and Actual Design Meaning
Logic Function	Octal D-type flip-flop with non-inverting 3-state outputs
Max Clock Frequency	270MHz (typ.) at VCC = 5V - enables high-speed synchronous data capture
Supply Voltage Range	2V to 6V - supports mixed-voltage system interfacing (e.g., 3.3V logic driving 5V bus)
Output Drive Strength	±24mA (min) - drives 50Ω transmission lines directly without external termination
Quiescent Current	4µA (max) at TA = 25°C - ultra-low static power for battery-sensitive or always-on logic
Propagation Delay	5.0ns (tPLH/tPHL typ.) at 5V - ensures tight timing margins in high-frequency control paths
Input Noise Immunity	28% VCC (min) - rejects common-mode noise in electrically noisy industrial environments

Pinout & Package

74AC374B is supplied in a plastic dual in-line package (DIP-20) with 0.3-inch body width and 2.54mm lead pitch. Pin 1 is marked by a notch or dot; leads are tin-plated and RoHS-compliant.

Pin/Terminal	Circuit Role	Design Meaning
1	OE	Active-low 3-state output enable - disables all Q outputs to high-impedance without affecting internal latch state
2,5,6,9,12,15,16,19	Q0–Q7	Non-inverting 3-state outputs - provide bidirectional bus isolation when OE = HIGH
3,4,7,8,13,14,17,18	D0–D7	Data inputs - sampled on rising edge of CK and held until next clock transition
11	CK	Clock input - positive-edge-triggered; controls synchronous capture of D inputs into Q outputs
10	GND	Ground reference (0V) - return path for all input/output currents and internal logic
20	VCC	Positive supply - powers internal logic and output drivers; must be decoupled locally

Key Features

Feature	Design Value
3-State Output Control	Independent OE pin allows dynamic bus arbitration without disrupting internal latch operation
Symmetrical Output Drive	IOH = IOL ≥ 24mA ensures matched rise/fall times and reduced signal distortion on shared buses
Wide Supply Range	2V–6V operation supports interoperability between legacy 5V and modern 3.3V/2.5V logic domains
High-Speed Timing	tPLH/tPHL ≤ 12ns (max) at 5V enables use in >80MHz system clocks with margin
ESD & Latch-Up Robustness	2kV HBM ESD rating and improved latch-up immunity ensure reliability in manufacturing and field environments

Applications

Industrial PLC I/O Modules

Legacy Bus Interface Adapters

Use Scenario: Isolating microcontroller GPIOs from noisy 24V industrial field buses while maintaining deterministic timing.

IC Role / Device Role / Timing Role: Synchronous data latch and 3-state bus buffer - captures sensor/actuator status on CK edge and presents it to MCU via OE-gated outputs.

Use Value: Enables clean read/write handshaking over long traces with 50Ω line matching and ±24mA drive, reducing signal reflections and timing jitter.

Use Scenario: Bridging ISA or PCI legacy expansion slots to modern FPGA-based controllers in test equipment.

IC Role / Device Role / Timing Role: Octal data register with tri-state control - holds configuration data during address decode and releases it onto shared data bus only when selected.

Use Value: Provides pin-compatible replacement for obsolete 74LS374 with 5× lower ICC and 2.5× higher fMAX, extending life of legacy board designs.

Automotive Body Control Units

Test & Measurement Instrumentation

Use Scenario: Managing multiplexed switch inputs and LED driver outputs in vehicle door modules under wide-temperature conditions.

IC Role / Device Role / Timing Role: Input latch and output buffer - samples mechanical switch states synchronously and drives discrete loads with controlled slew rate.

Use Value: −55°C to +125°C operation and 28% VCC noise margin ensure reliable function in under-hood thermal cycling and EMI-rich cabin environments.

Use Scenario: Implementing programmable pattern generators or digital stimulus sources requiring precise edge-aligned waveform generation.

IC Role / Device Role / Timing Role: High-speed data register - stores pattern words from memory and clocks them out with minimal skew across all 8 bits.

Use Value: Balanced tPLH/tPHL (≤1ns skew) and 5ns typical delay enable sub-10ns pulse width accuracy critical for jitter-sensitive signal integrity validation.

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal D-type flip-flop with 3-state output applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74AC374N	Same AC logic family, identical pinout and DC specs; TI version uses different process but matches tPLH/tPHL within 0.3ns	Qualified to AEC-Q100 Grade 2 for automotive; wider availability in tube packaging	Preferred for new automotive designs requiring qualification documentation and long-term supply assurance
74VHC374N	Lower drive (±8mA), higher ICC (20µA max), narrower VCC range (2V–5.5V); otherwise pin- and function-compatible	Used where lower power density and reduced EMI are prioritized over bus drive strength	Select when system trace impedance exceeds 75Ω or when 24mA drive causes excessive ground bounce

Compared with SN74AC374N and 74VHC374N, the 74AC374B delivers superior 50Ω line driving and lowest quiescent current, making it optimal for high-speed, noise-immune bus interfaces where signal integrity and power efficiency are jointly critical.

Availability

74AC374B is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, and test & measurement instrumentation requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74AC374B 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in automotive, industrial, and power management ICs with strong analog and mixed-signal design heritage.

The 74AC374B belongs to ST's legacy AC logic product line, engineered for high-speed, low-power, and robust operation in mission-critical industrial and automotive control systems where timing precision and noise resilience are essential.

FAQ

What is the maximum clock frequency supported by the 74AC374B at 3.3V?

The 74AC374B supports up to 250MHz (typical) at VCC = 3.3V, as specified in AC Electrical Characteristics (CL = 50pF, RL = 500Ω). This is validated across −40°C to +85°C ambient, with minimum guaranteed fMAX of 60MHz over full industrial temperature range.

Can the 74AC374B drive a 50Ω transmission line directly without external series termination?

Yes - the 74AC374B provides ±24mA (min) symmetrical output drive and is explicitly characterized for 50Ω transmission line driving capability. Its matched output impedance and fast edge rates allow direct connection to properly terminated 50Ω PCB traces without added series resistors.

Does the 74AC374B retain stored data when OE is asserted (HIGH)?

Yes - asserting OE (HIGH) places Q0–Q7 outputs in high-impedance state but does not affect internal latch operation. Data remains stored and can be updated on subsequent CK edges, enabling seamless bus arbitration without data loss or reinitialization.

Is the 74AC374B compatible with 3.3V-only systems despite its 2V–6V supply range?

Yes - the 74AC374B is fully functional at VCC = 3.3V, with VIH/VIL thresholds scaled to 30%/70% of VCC (e.g., VIH = 1.0V min, VIL = 0.66V max), ensuring reliable interfacing with 3.3V CMOS outputs and compatibility with mixed-voltage backplanes.

74AC374B Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: 74AC

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

Packaging:: Tube

Product Status:: Obsolete

Function:: Standard

Type:: D-Type

Output Type:: Tri-State, Non-Inverted

Number of Elements:: 1

Number of Bits per Element:: 8

Clock Frequency:: 270 MHz

Max Propagation Delay @ V, Max CL:: 9.5ns @ 5V, 50pF

Trigger Type:: Positive Edge

Current - Output High, Low:: 24mA, 24mA

Voltage - Supply:: 2V ~ 6V

Current - Quiescent (Iq):: 4 µA

Input Capacitance:: 4 pF

Operating Temperature:: -55°C ~ 125°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 20-SO

74AC374B FAQ

1.How can I place an order for 74AC374B through Aetrix?

Please submit a Request for Quotation (RFQ) for 74AC374B 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 74AC374B reliable?

The price and inventory of 74AC374B are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74AC374B is usually 5 days.

3.What payment methods are accepted for 74AC374B?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74AC374B transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 74AC374B?

74AC374B orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 74AC374B 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 74AC374B?

For technical support, including 74AC374B datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74AC374B requirements.

6.How does Aetrix verify that 74AC374B is sourced from the original manufacturer or authorized distributors?

All 74AC374B 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 74AC374B meets industry standards.

7.What is the process for return or replacement of 74AC374B?

All 74AC374B units undergo pre-shipment inspection (PSI). If there is an issue with 74AC374B, 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 74AC374B part is unused and in its original packaging.

Return procedure for 74AC374B:

1.Submit a request within 90 days.

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

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