Texas Instruments CD74HC74M

Overview

CD74HC74M from Texas Instruments is a dual D-type positive-edge-triggered flip-flop with independent asynchronous preset and clear inputs per channel, operating across 2 V to 6 V supply voltage and –55°C to +125°C temperature range. It delivers 35 MHz maximum clock frequency at 6 V, 30 ns typical propagation delay (CL = 50 pF), and supports fanout of up to 10 LSTTL loads. Used in clock division and momentary-to-toggle switch conversion circuits.

For engineers reviewing the CD74HC74M datasheet, CD74HC74M pinout, CD74HC74M application, or CD74HC74M equivalent, key selection considerations include its dual-channel asynchronous control architecture, SOIC-14 package compatibility, guaranteed timing performance over extended temperature, and CMOS power efficiency versus legacy TTL logic.

Technical Context

The CD74HC74M implements two fully independent D-type flip-flops, each with separate positive-edge-triggered clock (CLK), data (D), active-low preset (PRE), active-low clear (CLR), true (Q), and complement (Q̅) outputs. Its functional modes are defined by a deterministic truth table where PRE and CLR override clocked operation when asserted.

It uses standard CMOS input structure with 10 pF input capacitance and balanced push-pull outputs capable of ±25 mA continuous output current. Timing behavior is governed by setup time (10 ns min at 6 V), hold time (3 ns), and pulse width requirements (14 ns min for CLK/CLR/PRE at 6 V), all specified across full industrial temperature range.

Key Specifications

Pinout & Package

CD74HC74M is housed in a 14-pin SOIC (D) package measuring 8.70 mm × 3.90 mm, with gull-wing leads optimized for surface-mount reflow assembly and thermal performance (R_θJA = 133.6 °C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with CD74HC74M, SN74HC74DR offers improved manufacturability and long-term availability, while MC74HC74ADTR2G delivers marginally better dynamic power efficiency - both retain full functional and pin compatibility but differ in qualification scope and thermal metrics.

Availability

CD74HC74M is available at Aetrix Electronics and suitable for industrial control panels, automotive body electronics, aerospace avionics interfaces, and test equipment requiring stable component supply across extended temperature ranges.

Supply support for CD74HC74M 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 50 years of innovation in high-reliability logic families.

The CD74HC74M belongs to TI's 74HC logic series - designed for low-power, wide-voltage industrial and automotive applications where robustness, timing predictability, and long-term supply stability are critical.

FAQ

What is the maximum clock frequency supported by CD74HC74M at 3.3 V operation?

The CD74HC74M supports a maximum clock frequency of 25 MHz at 3.3 V (within recommended 2–6 V range), as specified in Section 6.5 of the datasheet. This value is derived from timing measurements at –40°C to +85°C ambient, with 15 ns minimum pulse width and 15 ns setup time. The CD74HC74M maintains full functionality across this range without derating.

Does CD74HC74M require external pull-up or pull-down resistors on unused inputs?

Yes, CD74HC74M requires all unused inputs to be terminated - either directly to V_CC or GND - to prevent floating nodes that cause undefined logic states and increased power consumption. A 10-kΩ resistor is commonly used when flexibility is needed; direct connection is preferred for fixed logic levels. Leaving inputs unconnected violates the device's absolute maximum ratings and risks erratic behavior.

Can CD74HC74M drive a 50-pF capacitive load while meeting all AC specifications?

Yes, CD74HC74M is fully characterized for 50-pF capacitive loads, as confirmed in Section 6.6 Switching Characteristics. Propagation delay (t_pd = 30 ns typ), transition time (t_t = 13 ns typ), and setup/hold times remain within spec under these conditions at 6 V. Exceeding 50 pF increases delay and may violate timing margins unless compensated with series output resistance.

Is CD74HC74M pin-compatible with CD74HC74E (PDIP-14) and CD74HC74M96 (SOIC-14 tape-and-reel)?

Yes, CD74HC74M is functionally and pinout-identical to CD74HC74E and CD74HC74M96 - all share the same 14-pin SOIC/D or PDIP/N footprint, identical pin numbering, and matching electrical behavior. Differences are limited to packaging format, reel quantity, and RoHS compliance status; no PCB layout changes are required when substituting among these variants.

What is the purpose of the complementary Q̅ outputs on CD74HC74M?

The complementary Q̅ outputs on CD74HC74M provide inverted registered data without external inversion, enabling direct implementation of toggle mode (D = Q̅), differential signaling, or synchronous reset/set logic. In CD74HC74M, each channel has dedicated Q and Q̅ pins - eliminating need for discrete inverters and reducing propagation delay in feedback paths critical for stable oscillator or counter designs.