Texas Instruments SN74HC574NS

Overview

SN74HC574NS from Texas Instruments is an octal edge-triggered D-type flip-flop with 3-state outputs, designed for bus driving in digital systems. It operates across 2 V to 6 V, delivers ±6 mA output drive at 5 V, exhibits typical propagation delay of 22 ns (VCC = 4.5 V, CL = 50 pF), and supports clock frequencies up to 24 MHz. It is used in I/O port buffering and bidirectional data bus control.

For engineers reviewing the SN74HC574NS datasheet, SN74HC574NS pinout, SN74HC574NS application, or SN74HC574NS equivalent, key selection criteria include its 20-pin SO package, 3-state output enable timing (ten/tdis ≤ 38 ns at 4.5 V), low ICC (80 µA max), and compatibility with LSTTL bus loading (up to 15 loads).

Technical Context

The SN74HC574NS implements eight independent D-type latches triggered on the rising edge of CLK, with synchronous data capture and asynchronous 3-state control via OE. Its internal logic retains stored data regardless of OE state, enabling seamless bus arbitration during read/write transitions.

It features bus-structured pinout for minimized trace crosstalk, CMOS input thresholds (VIH = 3.15 V, VIL = 1.35 V at VCC = 4.5 V), and robust noise immunity with input hysteresis implied by HC-series design. Thermal resistance RθJA is 113.4 °C/W in the SO package, requiring attention to PCB copper area for thermal management at sustained load.

Key Specifications

Pinout & Package

The SN74HC574NS is housed in a 20-pin small-outline package (SO) with 15.00 mm × 5.30 mm body size, gull-wing leads, and JEDEC MO-153-compliant footprint. It uses standard SOIC-compatible land patterns with 0.65 mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC574NS, SN74HCT574N offers stronger TTL input compatibility but lacks the SO package option, while 74LCX574MTCX delivers faster timing and lower voltage operation but cannot interface with 5 V buses - making SN74HC574NS the optimal choice for industrial 2–6 V mixed-signal bus buffering.

Availability

SN74HC574NS is available at Aetrix Electronics and suitable for industrial I/O expansion, microcontroller bus interfacing, and legacy system bus buffering requiring stable component supply and long-term production continuity.

Supply support for SN74HC574NS 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 industrial and automotive-grade IC design.

The SN74HC574NS belongs to TI's 74HC logic family, engineered for high noise immunity, low power consumption, and robust performance in industrial control, instrumentation, and bus-interface applications.

FAQ

What is the maximum clock frequency supported by the SN74HC574NS?

The SN74HC574NS supports a maximum clock frequency of 24 MHz under recommended operating conditions (VCC = 4.5 V, TA = –40 °C to +85 °C). This value is derived from timing specifications in the official TI datasheet SCLS148H, where fmax is specified as 24 MHz for SN74HC574 devices in commercial temperature range. The SN74HC574NS achieves this with 22 ns typical propagation delay and meets setup/hold timing margins at that rate.

Does the SN74HC574NS require external pull-up resistors on its outputs?

No, the SN74HC574NS does not require external pull-up resistors on its outputs. Its 3-state outputs provide active high- and low-level drive (±6 mA at 5 V) and high-impedance off-state, allowing direct connection to shared buses without passive termination. Pull-ups are unnecessary unless interfacing with open-drain systems - a configuration not supported by the SN74HC574NS output structure.

Can the SN74HC574NS operate reliably at 3.3 V supply voltage?

Yes, the SN74HC574NS operates reliably at 3.3 V supply voltage. Its specified supply range is 2 V to 6 V, and electrical characteristics including VIH (min 2.0 V at VCC = 3.3 V), VOL (max 0.1 V), and tpd (typ 27 ns) are fully characterized across this range. It is widely deployed in 3.3 V microcontroller interfaces and mixed-voltage industrial systems.

What is the function of the OE pin on the SN74HC574NS?

The OE (output enable) pin on the SN74HC574NS is an active-low control that places all eight Q outputs in high-impedance state when asserted high. When OE is low, outputs reflect the latched Q states. Critically, OE has no effect on internal flip-flop operation - data can be captured on CLK edges and retained regardless of OE state, enabling flexible bus arbitration.

Is the SN74HC574NS pin-compatible with other packages in the SN74HC574 family?

Yes, the SN74HC574NS is functionally and pinout-compatible with all 20-pin variants of the SN74HC574 family, including SN74HC574N (PDIP), SN74HC574DBR (SSOP), and SN74HC574PWR (TSSOP). All share identical pin functions, signal assignments, and logic behavior. However, mechanical dimensions, thermal resistance (RθJA = 113.4 °C/W for NS), and soldering profiles differ - PCB layout must match the SO package outline.