Texas Instruments SN74HCT574DW

Overview

SN74HCT574DW from Texas Instruments is an octal edge-triggered D-type flip-flop with 3-state noninverting outputs, operating at 4.5–5.5 V, delivering ±6 mA output drive, 22 ns typical propagation delay, and 80 μA max ICC. It serves as a bus-oriented buffer register in microcontroller I/O expansion and data latching applications.

For engineers reviewing the SN74HCT574DW datasheet, SN74HCT574DW pinout, SN74HCT574DW application, or SN74HCT574DW equivalent, this page delivers verified electrical specs, SOIC-20 package details, functional timing behavior, and validated alternative options for industrial bus interface design.

Technical Context

The SN74HCT574DW implements eight independent D-type flip-flops triggered on the low-to-high clock transition, each with individual D input and Q output. Its dual output-enable inputs (1OE and 2OE) control two groups of four outputs independently, enabling flexible bus segmentation.

It features TTL-compatible input thresholds (VIH = 2 V, VIL = 0.8 V), high-current 3-state outputs capable of driving up to 15 LSTTL loads, and logic-level retention during output disable - allowing data updates or hold operations while outputs remain in high-impedance state.

Key Specifications

Pinout & Package

SN74HCT574DW uses a 20-pin SOIC (DW) package measuring 12.80 mm × 10.3 mm (body: 12.80 mm × 7.50 mm), with gull-wing leads and standard JEDEC MO-001AC footprint.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT574DW, SN74HCT373DW offers simpler control but no clock synchronization, while 74ACT574SCX delivers faster switching at the cost of higher supply current and reduced noise immunity - making SN74HCT574DW optimal for balanced 5 V industrial bus interfacing.

Availability

SN74HCT574DW is available at Aetrix Electronics and suitable for microcontroller I/O expansion, parallel data latching, and memory-mapped peripheral interface applications requiring stable component supply and long-term industrial lifecycle support.

Supply support for SN74HCT574DW 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 50 years of innovation in industrial-grade digital ICs.

The SN74HCT574DW belongs to TI's 74HCT logic family, designed specifically for robust 5 V TTL-compatible bus interfacing in industrial control, test equipment, and legacy system upgrades.

FAQ

What is the maximum clock frequency supported by the SN74HCT574DW?

The SN74HCT574DW supports a maximum clock frequency of 24 MHz at VCC = 5 V and TA = 25°C with CL = 50 pF. This limit derives from its 38 ns typical enable-to-output delay and 22 ns propagation delay, ensuring setup/hold timing compliance in synchronous bus systems. Operation beyond this frequency risks metastability or data capture failure.

Does the SN74HCT574DW require external pull-up resistors on its outputs?

No, the SN74HCT574DW does not require external pull-up resistors on its outputs. Its 3-state outputs provide ±6 mA drive strength at 5 V, sufficient to directly drive 15 LSTTL loads or terminate standard 5 V bus lines. Pull-ups are only needed if interfacing with open-drain or high-impedance receivers outside its native specification.

Can unused input pins on the SN74HCT574DW be left floating?

No, unused input pins on the SN74HCT574DW must not be left floating. All unused inputs - including D, CLK, and OE - must be tied to either VCC or GND to prevent undefined logic states, excessive ICC, or oscillation. TI recommends tying unused OE pins to VCC (to disable outputs) and unused D/CLK inputs to GND unless actively used.

Is the SN74HCT574DW pin-compatible with other 74HCT-series octal latches?

Yes, the SN74HCT574DW is pin-compatible with SN74HCT373DW and SN74HCT573DW in the SOIC-20 (DW) package. All share identical pin assignments for VCC, GND, CLK, OE, D, and Q signals. However, functional differences exist: SN74HCT574DW is edge-triggered, while SN74HCT373DW is level-sensitive - requiring careful logic design review before substitution.

What thermal considerations apply to the SN74HCT574DW in continuous operation?

The SN74HCT574DW has a junction-to-ambient thermal resistance (RθJA) of 109.1°C/W in SOIC-20 package. At maximum ICC (80 μA) and worst-case ambient (85°C), self-heating remains negligible (<0.01°C). However, under heavy capacitive bus loading (e.g., CL > 100 pF), dynamic power dominates - thermal design should prioritize adequate copper pour and airflow if operating near 125°C junction limit.