STMicroelectronics 74ACT573B

Overview

74ACT573B from STMicroelectronics is an advanced high-speed CMOS octal D-type latch with non-inverting 3-state outputs, designed for bus interface and data latching in TTL/CMOS mixed-signal systems. It features 5 ns typical propagation delay at 5 V, ±24 mA symmetrical output drive, 4.5–5.5 V operating range, and pin/function compatibility with standard 74-series 573 devices.

For engineers reviewing the 74ACT573B datasheet, 74ACT573B pinout, 74ACT573B application, or 74ACT573B equivalent, key selection criteria include latch enable timing (1 ns min pulse width), 3-state output disable time (6.5 ns typ), input voltage thresholds (VIH ≥ 2.0 V, VIL ≤ 0.8 V), and ESD immunity (2 kV HBM).

Technical Context

The device implements dual-control latching via LE (latch enable) and OE (output enable), supporting transparent data flow when LE is high and precise edge-triggered capture when LE transitions low. Its sub-micron C2MOS process ensures latch-up immunity and stable operation across –55°C to +125°C.

All eight D-to-Q paths operate with balanced tPLH ≅ tPHL propagation, enabling deterministic timing in synchronous bus architectures. The 50 Ω transmission line driving capability and symmetrical |IOH| = IOL = 24 mA (min) support direct connection to terminated backplanes without external buffers.

Key Specifications

Pinout & Package

74ACT573B is supplied in a plastic DIP-20 (0.300" wide) package with 20 leads, 2.54 mm pitch, and through-hole mounting. Pin 1 is marked by a notch or dot; pin 10 is GND, pin 20 is VCC.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74ACT573M and SN74ACT573N, the 74ACT573B offers identical electrical performance in a legacy DIP-20 form factor optimized for prototyping and through-hole manufacturing, with no trade-offs in speed, drive strength, or temperature range.

Availability

74ACT573B is available at Aetrix Electronics and suitable for microprocessor bus interface, memory address latching, and industrial I/O expansion requiring stable component supply and long-term obsolescence management.

Supply support for 74ACT573B 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 analog, digital, and mixed-signal ICs for industrial, automotive, and consumer markets.

The 74ACT series targets high-speed, low-power logic interfacing in mixed-technology systems, emphasizing TTL compatibility, robust ESD protection, and wide-temperature reliability.

FAQ

What is the minimum recommended decoupling capacitance for 74ACT573B?

A 0.1 µF ceramic capacitor placed within 5 mm of pins 10 (GND) and 20 (VCC) is mandatory per STMicroelectronics layout guidelines. This suppresses high-frequency supply noise induced by simultaneous 24 mA output switching, preventing ground bounce and ensuring stable 5 ns propagation timing.

Can 74ACT573B drive a 50 Ω coaxial cable directly?

Yes - its 24 mA output drive and 50 Ω transmission line capability are verified per AC specifications with CL = 50 pF and RL = 50 Ω. For reliable 10 cm+ cable runs, maintain controlled impedance routing and terminate at the far end to prevent reflections that distort tPLZ/tPHZ timing.

Is the 74ACT573B latch edge-triggered or level-sensitive?

The latch is level-sensitive on LE: when LE is high, Q outputs follow D inputs transparently; when LE goes low, the current D values are captured and held. No internal clock - timing depends solely on LE signal stability and specified setup/hold windows (0 ns min ts/th at 25°C).

Does 74ACT573B require external pull-up resistors on Q outputs?

No - the 3-state outputs have active push-pull drivers and do not require pull-ups. External pull-ups would conflict with the specified VOL ≤ 0.5 V at 24 mA and may cause excessive current draw or logic contention when OE is asserted.