Texas Instruments SN74HCT273DWE4

Overview

SN74HCT273DWE4 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 serves as a synchronous storage register in digital control logic, bus interface buffering, and pattern generation circuits.

For engineers reviewing the SN74HCT273DWE4 datasheet, SN74HCT273DWE4 pinout, SN74HCT273DWE4 application, or SN74HCT273DWE4 equivalent, this page provides verified functional identity, validated SOIC-20 pin mapping, confirmed timing and drive specifications, and two technically documented alternative parts for register-level logic replacement.

Technical Context

The SN74HCT273DWE4 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 TTL-compatible inputs accept 0.8 V/2.0 V thresholds and exhibit ≤1 µA input current.

It operates strictly within 4.5–5.5 V supply range and supports up to 20 MHz clock frequency at 5 V over –40°C to +85°C ambient. Output switching characteristics are characterized with CL = 50 pF load and defined under push-pull conditions per JEDEC JESD8-6.

Key Specifications

Pinout & Package

SN74HCT273DWE4 is packaged in a 20-pin SOIC (DW) body measuring 12.8 mm × 10.3 mm, with 12.8 mm × 7.5 mm body size excluding leads. The package is RoHS-compliant, NIPDAU lead finish, MSL Level-1, and designed for surface-mount reflow assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT273DWE4, SN74HCT377N lacks asynchronous clear and requires clock-enable coordination, while 74ACT273SCX trades lower static power for faster switching and higher supply current - both require PCB-level validation for timing closure and thermal management.

Availability

SN74HCT273DWE4 is available at Aetrix Electronics and suitable for industrial control logic, microcontroller I/O expansion, and serial-to-parallel conversion requiring stable component supply across long-lifecycle production programs.

Supply support for SN74HCT273DWE4 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, embedded processing, and logic solutions with broad industrial and automotive qualification.

The SN74HCT273DWE4 belongs to TI's HCT logic family, engineered for 5 V TTL-compatible digital interfacing in cost-sensitive, temperature-stable embedded systems where low static power and noise immunity are prioritized.

FAQ

What is the function of Pin 1 (CLR) on the SN74HCT273DWE4?

Pin 1 is the active-low asynchronous clear input. When asserted (low), it forces all eight Q outputs to logic low immediately, regardless of clock state or input conditions. This function is independent of the CLK signal and provides deterministic initialization for system startup or fault recovery. The SN74HCT273DWE4 requires no clock edge to execute CLR - it responds within tpd (≤36 ns max) after the input transitions.

Does the SN74HCT273DWE4 support 3.3 V operation?

No, the SN74HCT273DWE4 does not support 3.3 V operation. Its absolute minimum supply voltage is 4.5 V, and recommended operating range is strictly 4.5 V to 5.5 V. Attempting to operate below 4.5 V may result in undefined output states, increased propagation delay, or failure to meet VIH/VIL thresholds. For 3.3 V systems, consider logic-level translators or 3.3 V-compatible alternatives such as SN74LVC273.

What is the maximum clock frequency supported by the SN74HCT273DWE4?

The SN74HCT273DWE4 supports a maximum clock frequency of 20 MHz at VCC = 4.5 V and TA = –40°C to +85°C. At VCC = 5.5 V, the rated fmax increases to 23 MHz under the same temperature range. These values are derived from timing requirements in the official TI datasheet (SCLS068H), where tw(CLK high/low) ≥ 22 ns defines the minimum pulse width constraint.

Can unused inputs on the SN74HCT273DWE4 be left floating?

No, unused inputs on the SN74HCT273DWE4 must not be left floating. All unused D inputs and the CLK and CLR lines must be tied to either VCC or GND to prevent undefined logic states, increased ICC, or unintended switching. TI specifically recommends connecting unused inputs to valid logic levels per SCBA004 guidelines - floating inputs can cause excessive current draw and erratic output behavior in HCT devices.

Is the SN74HCT273DWE4 pin-compatible with other 20-pin octal flip-flops like the SN74HCT377?

No, the SN74HCT273DWE4 is not pin-compatible with the SN74HCT377. While both are 20-pin SOIC octal D-type devices, SN74HCT273DWE4 uses Pin 1 for CLR and Pins 2–9/12/15–16/19 for Q outputs, whereas SN74HCT377 assigns Pin 1 to OE (output enable) and rearranges Q/D pin locations. Physical pin mapping differs - direct substitution would require PCB redesign. Always verify pin functions using TI's official pin configuration tables before replacement.