Texas Instruments SN74ACT574NS

Overview

SN74ACT574NS from Texas Instruments is an octal D-type edge-triggered flip-flop with 3-state outputs, designed for bus-oriented digital systems. It operates at 4.5 V to 5.5 V, features 9 ns max propagation delay at 5 V, TTL-compatible inputs, and supports rising-edge clock triggering. It is used in I/O port buffering, bidirectional bus driving, and working register applications in industrial control and data acquisition systems.

For engineers reviewing the SN74ACT574NS datasheet, SN74ACT574NS pinout, SN74ACT574NS application, or SN74ACT574NS equivalent, key selection criteria include its 20-pin SOP (NS) package, 3-state output enable control, 8-bit synchronous latch behavior, and compatibility with 5-V TTL logic families in high-capacitance bus environments.

Technical Context

The SN74ACT574NS implements eight independent D-type flip-flops sharing a common clock (CLK) input and a single active-low output-enable (OE) control. On each rising edge of CLK, all Q outputs update synchronously to match their corresponding D inputs. OE independently places all outputs in high-impedance state without affecting internal storage - enabling dynamic bus arbitration and multi-master system design.

Its ACT (Advanced CMOS TTL-compatible) logic family ensures robust noise immunity, 5-V supply operation, and drive capability up to ±24 mA per output. Input voltage tolerance extends to 5.5 V, allowing safe interfacing with mixed-voltage subsystems while maintaining full 5-V logic thresholds (VIH = 2 V, VIL = 0.8 V).

Key Specifications

Pinout & Package

SOP-20 (NS) package: 12.6 mm × 7.8 mm body size, 12.6 mm × 5.3 mm footprint, 1.75 mm max height, gull-wing leads, RoHS-compliant NIPDAU finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT574NS, SN74ACT573NS offers simpler control but lacks clock synchronization, while 74ACT273NS provides reset capability at the cost of bus-driving flexibility - making SN74ACT574NS uniquely suited for synchronous, shared-bus register applications.

Availability

SN74ACT574NS is available at Aetrix Electronics and suitable for industrial automation, test equipment, and legacy microprocessor interface designs requiring stable component supply, long-term lifecycle support, and RoHS-compliant 5-V logic performance.

Supply support for SN74ACT574NS 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 over 90 years of innovation in industrial, automotive, and communications markets.

The SN74ACT574NS belongs to TI's Advanced CMOS (ACT) logic family, engineered for high-speed, low-noise 5-V digital interfacing in mission-critical industrial and instrumentation systems.

FAQ

What is the maximum clock frequency supported by the SN74ACT574NS?

The SN74ACT574NS supports a maximum clock frequency of 85 MHz under recommended operating conditions (VCC = 5 V, TA = –40 °C to +85 °C). This is derived from its 9 ns maximum propagation delay and verified timing parameters including minimum pulse width (3 ns) and setup/hold times (2.5 ns / 1 ns). The SN74ACT574NS achieves this performance while maintaining full 3-state output control and TTL-compatible input thresholds.

Does the SN74ACT574NS require external pull-up resistors on the OE pin?

Yes - to ensure the outputs remain in high-impedance state during power-up or power-down, the OE pin of the SN74ACT574NS should be tied to VCC via a pull-up resistor. TI recommends a value determined by the current-sinking capability of the driving source; typical values range from 4.7 kΩ to 10 kΩ. This prevents bus contention before system initialization completes, and applies specifically to the SN74ACT574NS in its SOP-20 (NS) configuration.

Can the SN74ACT574NS operate reliably at 4.5 V supply voltage?

Yes - the SN74ACT574NS is fully specified for operation from 4.5 V to 5.5 V. At 4.5 V, it maintains guaranteed output drive (±24 mA), TTL-compatible input thresholds (VIH = 2 V min, VIL = 0.8 V max), and 9 ns max propagation delay. Electrical characteristics including VOL (0.44 V max at IOL = 24 mA) and VOH (3.76 V min at IOH = –24 mA) are validated across this range, confirming robust SN74ACT574NS performance in brown-out or wide-tolerance 5-V rail environments.

Is the SN74ACT574NS pin-compatible with other package variants like SN74ACT574DBR or SN74ACT574PWR?

No - while all SN74ACT574 variants share identical logic functionality and pin numbering, the SN74ACT574NS (SOP-20) is not mechanically pin-compatible with SN74ACT574DBR (SSOP-20) or SN74ACT574PWR (TSSOP-20) due to differing lead pitch (1.27 mm for NS vs. 0.65 mm for DB/PW) and body dimensions. PCB layout must be redesigned for each package; however, the SN74ACT574NS pinout matches exactly with SN74ACT574DWR (SOIC-20) in terms of spacing and pad geometry.

What is the thermal resistance (RθJA) of the SN74ACT574NS package?

The junction-to-ambient thermal resistance (RθJA) for the SN74ACT574NS in its SOP-20 (NS) package is 106.2 °C/W, as specified in TI's latest revision (F, February 2024) of the datasheet. This value assumes standard JEDEC high-K board conditions (2S2P) and confirms the SN74ACT574NS can dissipate up to ~400 mW continuously at +85 °C ambient without exceeding its 150 °C maximum junction temperature - supporting reliable operation in compact industrial enclosures.