Texas Instruments SN74AC574NSR

Overview

SN74AC574NSR from Texas Instruments is an octal D-type edge-triggered flip-flop with 3-state outputs, designed for bus interface and data latching in digital systems operating from 2V to 6V. It features 20-pin SSOP packaging, 8.5ns max propagation delay at 5V, ±24mA output drive, and supports rising-edge clock triggering with active-low output enable. It is used in I/O port expansion and bidirectional bus buffering applications.

For engineers reviewing the SN74AC574NSR datasheet, SN74AC574NSR pinout, SN74AC574NSR application, or SN74AC574NSR equivalent, key selection criteria include VCC range (2–6V), tPLH/tPHL timing at 3.3V/5V, 3-state output control logic, thermal resistance (RθJA = 60°C/W), and compatibility with standard TTL/CMOS logic levels.

Technical Context

This device implements eight independent D-type flip-flops synchronized to the rising edge of CLK, with a shared active-low OE input enabling high-impedance output states. Its AC logic family delivers rail-to-rail input tolerance (up to 6V) and robust noise immunity across industrial temperature range (−40°C to 85°C).

The architecture supports simultaneous data capture and bus isolation: data on D1–D8 is latched on CLK↑ while OE controls whether Q1–Q8 drive the bus or enter high-Z mode-without affecting internal state retention or clock/data sequencing behavior.

Key Specifications

Pinout & Package

SN74AC574NSR uses a 20-pin SSOP (DB) package measuring 7.2mm × 7.8mm with 0.65mm lead pitch and 2mm max height. The package includes exposed thermal pad (optional GND connection) and conforms to JEDEC MO-150.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AC574NSR, the LV574AQPWRQ1 offers automotive qualification and lower voltage support but sacrifices speed and thermal efficiency, while the 74AC574SCX matches logic behavior exactly but trades SSOP's compact size for SOIC's larger footprint and higher thermal resistance.

Availability

SN74AC574NSR is available at Aetrix Electronics and suitable for industrial automation, test equipment, and embedded communication gateway designs requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74AC574NSR 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 global semiconductor leader specializing in analog, embedded processing, and logic solutions, with decades of experience in high-reliability industrial and automotive components.

SN74AC574NSR belongs to the AC logic family designed for high-speed, low-power, mixed-voltage digital interfacing in industrial control, instrumentation, and communications infrastructure.

FAQ

What is the maximum clock frequency supported by SN74AC574NSR at 5V?

At VCC = 5V ± 0.5V, SN74AC574NSR supports a maximum clock frequency of 85MHz under recommended operating conditions. This is derived from the minimum clock pulse width (5ns high/low) and verified by timing characteristics tables in the official datasheet SCAS541G. The device maintains reliable setup and hold margins within this limit across its full industrial temperature range.

Does SN74AC574NSR require external pull-up resistors on the OE pin?

Yes - for defined high-impedance behavior during power-up or power-down sequences, SN74AC574NSR requires OE to be tied to VCC via a pull-up resistor. TI recommends a value determined by the driving source's current-sinking capability; typical values range from 4.7kΩ to 10kΩ. Leaving OE floating risks undefined output states and potential bus contention.

Can SN74AC574NSR safely interface with 5V logic while powered from 3.3V?

Yes - SN74AC574NSR accepts input voltages up to 6V regardless of VCC level, so it can reliably receive 5V logic signals even when VCC = 3.3V. This rail-to-rail input tolerance eliminates the need for external level-shifting circuitry in mixed-voltage systems, a key advantage confirmed in Section 4.2 of the SCAS541G datasheet.

What is the thermal resistance (RθJA) of SN74AC574NSR in its SSOP package?

SN74AC574NSR in the DB (SSOP-20) package has a junction-to-ambient thermal resistance (RθJA) of 60°C/W, as specified in Section 4.3 of the SCAS541G datasheet. This value assumes standard JEDEC high-K board conditions and enables accurate junction temperature estimation for thermal design validation in industrial applications.

How does the 3-state output control work on SN74AC574NSR?

SN74AC574NSR uses an active-low output enable (OE) signal: when OE is low, Q1–Q8 reflect the latched D1–D8 values; when OE is high, all eight outputs enter high-impedance state regardless of clock or data activity. This behavior is fully decoupled from internal flip-flop operation - data can be updated or retained while outputs remain isolated, enabling flexible bus arbitration schemes.