Texas Instruments SN74HCT273DW

Overview

SN74HCT273DW from Texas Instruments is an octal positive-edge-triggered D-type flip-flop with common asynchronous clear (CLR), operating at 4.5–5.5 V, delivering 12 ns typical propagation delay, ±4 mA output drive, and 80 µA maximum ICC. It functions as a synchronous storage register in digital control logic, data buffering, and pattern generation circuits.

For engineers reviewing the SN74HCT273DW datasheet, SN74HCT273DW pinout, SN74HCT273DW application, or SN74HCT273DW equivalent, this page provides verified functional identity, SOIC-20 package mapping, timing-critical parameters (tpd, tsu, fmax), TTL-compatible input thresholds, and validated alternative options for register-level logic design.

Technical Context

The SN74HCT273DW implements eight independent D-type latches synchronized to the rising edge of CLK, with a shared active-low CLR that forces all Q outputs low regardless of clock state. Its HCT logic family ensures TTL-voltage compatibility while maintaining CMOS power efficiency.

Each flip-flop follows a strict function table: CLR = L forces Q = L; CLR = H enables clocked transfer of D to Q on CLK↑; CLK held high or low isolates D inputs. No internal latching of clock-unlike SN74HCT377-making it suitable for transparent register control with immediate reset capability.

Key Specifications

Pinout & Package

SN74HCT273DW is housed in a 20-pin SOIC (DW) package measuring 12.80 mm × 10.3 mm (body: 12.8 mm × 7.5 mm), with standard gull-wing leads and 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT273DW, SN74HCT377DW trades asynchronous clear for clock-enable functionality - requiring redesign of reset logic - while 74ACT273SCX delivers faster timing at the cost of doubled quiescent current and reduced noise margin.

Availability

SN74HCT273DW is available at Aetrix Electronics and suitable for buffer registers, shift register stages, digital control sequencers, and pattern generator subsystems requiring stable component supply across industrial temperature ranges.

Supply support for SN74HCT273DW 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 U.S.-based semiconductor company specializing in analog and embedded processing solutions, with over 90 years of innovation in logic, power, and signal chain technologies.

The SN74HCT273DW belongs to TI's HCT logic family - designed for TTL-compatible 5 V systems requiring low power, noise immunity, and guaranteed timing performance in industrial control and instrumentation.

FAQ

What is the function of Pin 1 (CLR) on the SN74HCT273DW?

Pin 1 is the active-low asynchronous clear input. When asserted low, it forces all eight Q outputs to logic low immediately - independent of the clock signal. This provides deterministic reset capability for system initialization or fault recovery. The SN74HCT273DW retains this behavior across its full operating temperature range (–40 °C to +85 °C) and supply voltage (4.5–5.5 V).

Does the SN74HCT273DW support mixed-voltage interfacing?

No - the SN74HCT273DW is strictly a 5 V device with TTL-compatible input thresholds (VIH = 2 V, VIL = 0.8 V) and operates only within 4.5–5.5 V. It does not support 3.3 V or 2.5 V logic levels on inputs or outputs. Interfacing with lower-voltage systems requires level translation, as confirmed by TI's recommended operating conditions and electrical characteristics tables.

What is the maximum clock frequency supported by the SN74HCT273DW?

The SN74HCT273DW supports up to 23 MHz maximum clock frequency at VCC = 5.5 V and TA = +85 °C, per TI's switching characteristics table. At 25 °C and 5 V, fmax reaches 37 MHz. Designers must observe minimum pulse width (tw ≥ 22 ns at 5.5 V) and setup time (tsu ≥ 21 ns) to guarantee reliable operation at these rates.

Can unused inputs on the SN74HCT273DW be left floating?

No - all unused inputs on the SN74HCT273DW must be tied to VCC or GND. Floating inputs cause undefined logic states, increased ICC, and potential oscillation due to intermediate voltage levels. TI explicitly mandates this in Section 5.2 and Application Note SCBA004 to ensure stable operation and prevent EMI or latch-up risks.

Is the SN74HCT273DW pin-compatible with other 20-pin octal D flip-flops?

Yes - the SN74HCT273DW shares identical SOIC-20 (DW) pinout and function mapping with SN74HCT377DW and SN74ACT273SCX, including CLK on Pin 11, CLR on Pin 1, and Q/D assignments. However, functional differences (e.g., CLR vs. OE) mean substitution requires verification of reset/control logic compatibility, not just physical fit.