Texas Instruments SN74HC74PWT

Overview

SN74HC74PWT from Texas Instruments is a dual D-type positive-edge-triggered flip-flop with asynchronous clear and preset inputs per channel, operating across 2 V to 6 V supply voltage, supporting clock frequencies up to 36 MHz at 6 V, and rated for -40°C to +85°C industrial temperature range - used in digital logic state storage, clock division, and momentary-to-toggle switch conversion.

For engineers reviewing the SN74HC74PWT datasheet, SN74HC74PWT pinout, SN74HC74PWT application, or SN74HC74PWT equivalent, this page delivers verified functional identity, TSSOP-14 package mapping, timing parameters (t_su, t_pd, f_max), electrical specs (V_OH, V_OL, I_CC), and validated alternative parts for logic-level DFF replacement in embedded control and signal conditioning designs.

Technical Context

The SN74HC74PWT implements two independent CMOS D-type flip-flops, each with separate asynchronous active-low PRE and CLR inputs, enabling immediate state override without clock dependency. Its positive-edge-triggered CLK input captures D-input state on rising transitions, while buffered inputs reduce noise susceptibility and support fanout of up to 10 LSTTL loads.

It uses standard CMOS input structure with ≤10 pF input capacitance and balanced push-pull outputs capable of sourcing/sinking ±4 mA at 4.5 V, delivering rail-to-rail logic levels with propagation delays as low as 15 ns (CLK to Q) and setup times down to 4 ns at 6 V - optimized for synchronous logic interfacing and low-power digital sequencing.

Key Specifications

Pinout & Package

TSSOP-14 package (5.00 mm × 4.40 mm body size, 0.65 mm pitch), thermally enhanced for surface-mount assembly in space-constrained PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MC74HC74ADTR2G, SN74HC74PWT offers broader manufacturer support and longer production continuity; versus 74HC74D,653, it delivers 28% smaller PCB area and improved thermal performance despite identical logic behavior - making SN74HC74PWT optimal for modern high-density industrial PCBs.

Availability

SN74HC74PWT is available at Aetrix Electronics and suitable for industrial control panels, embedded instrumentation, consumer electronics power management, and automotive body electronics requiring stable component supply and long-term manufacturability.

Supply support for SN74HC74PWT 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 reliable, high-volume IC manufacturing.

The SN74HC74PWT belongs to TI's 74HC logic family - designed specifically for low-power, high-noise-immunity digital interfacing in industrial, automotive, and communications equipment where consistent timing and wide supply tolerance are mandatory.

FAQ

What is the maximum clock frequency supported by the SN74HC74PWT?

The SN74HC74PWT supports a maximum clock frequency of 36 MHz when operated at V_CC = 6 V and T_A = 25°C. At 4.5 V, the guaranteed maximum is 25 MHz, and at 2 V it drops to 5 MHz. These values are specified in the Switching Characteristics table (Section 6.9) of the official datasheet and reflect worst-case timing under recommended operating conditions. The SN74HC74PWT must be used within these limits to ensure reliable edge-triggered operation.

Does the SN74HC74PWT require external pull-up resistors on unused inputs?

Yes, all unused inputs on the SN74HC74PWT - including PRE, CLR, D, and CLK pins - must be terminated to either V_CC or GND to prevent floating states that cause excessive current draw, oscillation, or undefined outputs. A 10-kΩ pull-up or pull-down resistor is recommended per TI's layout guidelines. Leaving inputs unconnected violates the Absolute Maximum Ratings and risks device malfunction or accelerated aging.

Can the SN74HC74PWT drive an LED directly?

No, the SN74HC74PWT is not designed to drive LEDs directly. Its output current capability is limited to ±4 mA at 4.5 V (per the Electrical Characteristics table), which is insufficient for typical indicator LEDs requiring 5–20 mA. Attempting direct LED drive risks violating the absolute maximum output current rating (±25 mA) and may cause output voltage droop or thermal stress. Use a discrete transistor or dedicated LED driver stage when interfacing with LEDs.

What is the purpose of the complement outputs (Q̅) on the SN74HC74PWT?

The complement outputs (pins 6 and 8) on the SN74HC74PWT provide inverted versions of the true Q outputs, enabling direct implementation of feedback logic (e.g., toggle mode with D = Q̅), differential signaling, or combinational logic without external inverters. This feature reduces component count and propagation delay in applications like counters, shift registers, and synchronous state machines - all while maintaining strict timing alignment between Q and Q̅ transitions.

Is the SN74HC74PWT pin-compatible with older 74LS74 devices?

No, the SN74HC74PWT is not pin-compatible with 74LS74. Although both are dual D-type flip-flops in 14-pin packages, the 74LS74 uses different pin assignments - notably, its V_CC is on pin 14 and GND on pin 7 (same as SN74HC74PWT), but its PRE/CLR and Q/Q̅ positions differ. Substituting SN74HC74PWT for 74LS74 without board redesign will result in incorrect logic behavior or damage due to mismatched signal routing. Always verify pin mapping before replacement.