Texas Instruments SN74AHCT74PWG4

Overview

SN74AHCT74PWG4 from Texas Instruments is a dual positive-edge-triggered D-type flip-flop with independent preset (PRE) and clear (CLR) inputs, operating at 4.5–5.5 V supply, delivering ±8-mA output drive, TTL-compatible inputs, and 5-ns minimum setup time. It functions as a synchronous storage element in digital control logic, clock division, and signal conditioning circuits.

For engineers reviewing the SN74AHCT74PWG4 datasheet, SN74AHCT74PWG4 pinout, SN74AHCT74PWG4 application, or SN74AHCT74PWG4 equivalent, key selection criteria include its 14-pin TSSOP package, guaranteed 5-V operation, dual independent flip-flop architecture with asynchronous set/reset, and compatibility with legacy TTL-level signaling in industrial and embedded timing systems.

Technical Context

The SN74AHCT74PWG4 implements two identical, electrically isolated D-type latches triggered on the rising edge of CLK. Each flip-flop features active-low asynchronous PRE and CLR inputs that override clocked data transfer, enabling immediate state initialization or reset independent of clock timing.

Its TTL-compatible input thresholds (VIL = 0.8 V, VIH = 2.0 V) ensure reliable interfacing with 5-V TTL logic families, while balanced CMOS push-pull outputs provide symmetrical sourcing/sinking capability up to ±8 mA at 5 V - supporting direct driving of multiple standard logic loads without external buffers.

Key Specifications

Pinout & Package

PW package: 14-pin Thin Shrink Small Outline Package (TSSOP), 5.0 mm × 6.4 mm body size, 0.65 mm lead pitch, thermal pad optional (not electrically connected in this variant).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHCT74D and 74LVC74AD, the SN74AHCT74PWG4 uniquely combines 5-V TTL compatibility, TSSOP space savings, and guaranteed 5-ns setup timing - making it optimal for retrofitting legacy 5-V systems with modern surface-mount reliability and density.

Availability

SN74AHCT74PWG4 is available at Aetrix Electronics and suitable for industrial control panels, embedded instrumentation interfaces, and automotive body electronics requiring stable component supply, long-term manufacturability, and RoHS-compliant packaging.

Supply support for SN74AHCT74PWG4 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 90 years of innovation in industrial, automotive, and communications markets.

The SN74AHCT74PWG4 belongs to TI's AHCT logic family - engineered for seamless 5-V TTL-to-CMOS bridging in legacy system upgrades, offering speed, noise immunity, and backward compatibility without redesign overhead.

FAQ

What is the recommended bypass capacitor for SN74AHCT74PWG4?

A 0.1-µF ceramic capacitor placed physically adjacent to the VCC and GND pins is required for stable operation of the SN74AHCT74PWG4. This minimizes high-frequency supply noise and prevents output glitches during switching transients. TI also recommends paralleling with a 1-µF capacitor to suppress lower-frequency ripple, especially in multi-device systems where shared power rails introduce coupling.

Can SN74AHCT74PWG4 operate at 3.3 V?

No, SN74AHCT74PWG4 is not rated for 3.3-V operation. Its recommended supply range is strictly 4.5 V to 5.5 V, and its TTL-compatible inputs require VIH ≥ 2.0 V and VIL ≤ 0.8 V - parameters validated only at 5 V. Attempting 3.3-V operation risks undefined logic states, increased propagation delay, and potential failure to meet setup/hold timing, as confirmed in Section 6.3 of the official datasheet.

Does SN74AHCT74PWG4 support hot swapping or live insertion?

No, SN74AHCT74PWG4 does not support hot swapping. Its absolute maximum ratings specify no voltage on inputs before VCC is applied, and the device lacks bus-hold or power-up protection circuitry. Applying signals to any pin prior to VCC stabilization can cause latch-up or excessive current flow through internal clamp diodes, risking permanent damage. Always power VCC before asserting inputs.

What is the maximum capacitive load SN74AHCT74PWG4 can drive while meeting timing specs?

SN74AHCT74PWG4 is characterized for loads up to 50 pF while maintaining full timing compliance (setup, hold, propagation delay). Driving >50 pF increases rise/fall times and delays, potentially violating setup/hold windows in high-speed systems. For heavier loads, add a buffer stage or reduce trace length and capacitance - TI's application note SCLA015 details layout techniques to maintain <50 pF total node capacitance for reliable SN74AHCT74PWG4 operation.

How should unused inputs be terminated on SN74AHCT74PWG4?

All unused inputs on SN74AHCT74PWG4 - including PRE, CLR, CLK, and D - must be tied to a valid logic level: either VCC (for HIGH default) or GND (for LOW default). Floating inputs risk oscillation, excess current draw, and unpredictable output states due to CMOS input sensitivity. A 10-kΩ pull-up or pull-down resistor is recommended when the input may be driven later; direct connection is acceptable for permanently unused pins.