Texas Instruments SN74HC74DRE4

Overview

SN74HC74DRE4 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 and -40°C to +85°C temperature range. It delivers 30 MHz max clock frequency at 4.5 V, 39 ns typical propagation delay (CLK to Q), and supports fanout of up to 10 LSTTL loads. It is used in digital logic control circuits requiring reliable edge-triggered state storage and clock division.

For engineers reviewing the SN74HC74DRE4 datasheet, SN74HC74DRE4 pinout, SN74HC74DRE4 application, or SN74HC74DRE4 equivalent, this page provides verified functional identity, SOIC-14 package mapping, timing parameters (tsu = 20 ns, th = 0 ns at 4.5 V), power dissipation capacitance (Cpd = 35 pF), and confirmed alternatives for toggle-switch implementation and clock division tasks.

Technical Context

The SN74HC74DRE4 implements two independent CMOS D-type flip-flops sharing no internal coupling - each with dedicated asynchronous active-low PRE and CLR inputs, buffered data (D) and clock (CLK) inputs, and complementary Q/Q̅ outputs. Its positive-edge-triggered behavior ensures state capture only on rising CLK transitions, while asynchronous controls override clocked operation.

It uses standard CMOS input structure (high-impedance, 10 pF max input capacitance) and balanced push-pull output drivers capable of ±4 mA (at VOH/VOL specs) with 39 ns typical tpd (CLK→Q) and 16 ns typical transition time (tt) at 6 V. No internal clamping diodes are enabled beyond those specified in absolute maximum ratings.

Key Specifications

Pinout & Package

SN74HC74DRE4 is packaged in a 14-pin SOIC (Small Outline Integrated Circuit) with nominal body size 8.70 mm × 3.90 mm and standard JEDEC MO-002AC footprint. Pin 1 is marked by a beveled corner or dot; pin numbering follows counterclockwise convention from top-left when viewed from component side.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC74DRE4, SN74HCT74DR offers guaranteed TTL input compatibility at the cost of reduced low-voltage operation, while MC74HC74ADTR2G delivers identical functionality in a smaller TSSOP package with trade-offs in thermal performance and soldering process requirements.

Availability

SN74HC74DRE4 is available at Aetrix Electronics and suitable for industrial control panels, embedded timing subsystems, and digital logic prototyping requiring stable component supply, long-term manufacturability, and RoHS-compliant packaging.

Supply support for SN74HC74DRE4 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 founded in 1930, specializing in analog and embedded processing technologies with global manufacturing, testing, and logistics infrastructure.

SN74HC74DRE4 belongs to TI's industry-standard 74HC logic family, designed for general-purpose digital logic implementation where low power, wide voltage operation, and predictable timing are essential - especially in cost-sensitive industrial and consumer electronics.

FAQ

What is the maximum clock frequency supported by SN74HC74DRE4?

The SN74HC74DRE4 supports a maximum clock frequency of 31 MHz at 4.5 V supply and 25°C ambient temperature, dropping to 25 MHz across the full -40°C to +85°C operating range. This value is measured under standard load conditions (CL = 50 pF) and reflects guaranteed timing performance per TI's SCLS094F datasheet Section 6.7.

Does SN74HC74DRE4 require external pull-up or pull-down resistors on unused inputs?

Yes - all unused inputs on SN74HC74DRE4 must be terminated to either VCC or GND to prevent floating states that cause excessive current draw or undefined logic behavior. A 10-kΩ resistor is recommended for default HIGH (pull-up) or LOW (pull-down) biasing, as specified in Section 9.2.1.2 of the official datasheet.

Can SN74HC74DRE4 operate reliably at 3.3 V supply voltage?

Yes - SN74HC74DRE4 is fully specified for operation from 2 V to 6 V, including 3.3 V. At 3.3 V, it maintains VIH = 2.31 V (min), VIL = 0.99 V (max), and delivers typical tpd = 44 ns (CLK→Q), making it suitable for direct interface with 3.3 V microcontrollers and FPGAs without level translation.

What is the function of the 1Q̅ and 2Q̅ pins on SN74HC74DRE4?

The 1Q̅ and 2Q̅ pins on SN74HC74DRE4 provide logically inverted outputs corresponding to 1Q and 2Q. They are actively driven complementary signals - not open-drain - and enable direct feedback (e.g., connecting 1Q̅ to 1D for toggle operation) or differential signal routing without external inverters.

Is SN74HC74DRE4 pin-compatible with older 74LS74 devices?

No - while SN74HC74DRE4 matches the 74LS74's 14-pin SOIC footprint and functional pinout (same pin assignments for CLK, D, PRE, CLR, Q, Q̅, VCC, GND), it is not electrically pin-compatible due to differing input thresholds, output drive strength, and timing characteristics. Direct replacement requires validation of voltage levels, fanout, and timing margins in the target circuit.