Texas Instruments SN74HCT273PWT

Overview

SN74HCT273PWT from Texas Instruments is an octal positive-edge-triggered D-type flip-flop with asynchronous active-low clear (CLR), operating at 4.5–5.5 V, delivering 12 ns typical propagation delay (tpd), ±4 mA output drive at 5 V, 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 SN74HCT273PWT datasheet, SN74HCT273PWT pinout, SN74HCT273PWT application, or SN74HCT273PWT equivalent, this page provides verified functional behavior, TSSOP-20 package details, timing constraints for 20 MHz operation at 85°C, and validated alternatives for register-level logic replacement.

Technical Context

The SN74HCT273PWT implements eight independent D-type latches synchronized to the rising edge of CLK, with a shared asynchronous CLR input that forces all Q outputs low regardless of clock state. Its TTL-compatible inputs accept 0.8 V/2.0 V thresholds and drive up to 10 LSTTL loads.

It operates strictly within 4.5–5.5 V supply range and supports industrial temperature range (–40°C to +85°C). Propagation delay is specified at 12 ns (typ) and ≤36 ns (max) under 5.5 V, with setup time (tsu) of 21 ns and hold time (th) of 0 ns - enabling reliable timing in high-speed synchronous systems without additional data stabilization.

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.5 mm × 6.4 mm body size, 1.2 mm max height, 0.65 mm lead pitch, exposed thermal pad (optional GND connection).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT273PWT, SN74HCT377PWR trades asynchronous reset for clock gating - reducing control flexibility but enabling selective register updates; 74ACT273MTCX delivers faster timing at the cost of higher power and stricter input compatibility requirements.

Availability

SN74HCT273PWT is available at Aetrix Electronics and suitable for industrial control registers, microcontroller I/O expansion, serial-to-parallel conversion, and digital pattern generator applications requiring stable component supply and long-term obsolescence management.

Supply support for SN74HCT273PWT 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 ICs, with over 50 years of leadership in industrial and automotive-grade logic solutions.

The SN74HCT273PWT belongs to TI's HCT logic family, designed specifically for 5 V TTL-compatible digital systems requiring low power, predictable timing, and industrial temperature resilience.

FAQ

What is the maximum clock frequency supported by the SN74HCT273PWT?

The SN74HCT273PWT supports a maximum clock frequency of 23 MHz at 5.5 V and –40°C to +85°C, based on its 22 ns minimum clock pulse width (tw) and 21 ns setup time (tsu). This rating ensures reliable operation in synchronous register applications without violating timing margins under worst-case voltage and temperature conditions. The SN74HCT273PWT datasheet specifies fmax = 23 MHz for SN74HCT273 devices at 5.5 V and 85°C.

Does the SN74HCT273PWT require external pull-up or pull-down resistors on unused inputs?

Yes - all unused inputs of the SN74HCT273PWT must be tied to either VCC or GND to prevent floating states that cause undefined outputs and increased power consumption. The device datasheet explicitly mandates this practice to ensure stable operation and avoid false triggering. Leaving inputs unconnected violates recommended operating conditions and may compromise reliability in the SN74HCT273PWT.

Can the SN74HCT273PWT operate with a 3.3 V supply?

No - the SN74HCT273PWT is not rated for 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 power the SN74HCT273PWT at 3.3 V will result in non-functional behavior, including failure to recognize logic thresholds and inability to drive LSTTL loads. Use SN74LVC273 or similar 3.3 V–compatible logic for lower-voltage systems.

What is the function of the thermal pad on the SN74HCT273PWT TSSOP package?

The exposed thermal pad on the SN74HCT273PWT TSSOP package may be connected to GND or left floating - it is not electrically required for functionality. When used, it improves thermal dissipation by lowering junction-to-board resistance (RθJB = 82.8°C/W). TI documentation states it must not be connected to any signal or supply other than GND. Proper soldering of the pad enhances long-term reliability under sustained load in the SN74HCT273PWT.

Is the SN74HCT273PWT pin-compatible with the SN74HCT273PW?

Yes - SN74HCT273PWT and SN74HCT273PW share identical TSSOP-20 (PW) package dimensions, pinout, and electrical specifications. The "T" suffix denotes tape-and-reel packaging (2000 pcs/reel), while "PW" refers to the base part number designation. Both are functionally and mechanically interchangeable; the SN74HCT273PWT is the orderable tape-and-reel variant of the SN74HCT273PW device.