Texas Instruments CD74AC74E

Overview

CD74AC74E from Texas Instruments is a dual positive-edge-triggered D-type flip-flop with independent asynchronous clear (CLR) and preset (PRE) inputs per channel, operating across 1.5 V to 5.5 V supply range, delivering 125 MHz max clock frequency at 5 V, ±24 mA output drive, and balanced propagation delays for synchronous logic control in industrial timing and data latching applications.

For engineers reviewing the CD74AC74E datasheet, CD74AC74E pinout, CD74AC74E application, or CD74AC74E equivalent, this device serves as a high-noise-immunity, low-power CMOS alternative to bipolar F/AS/S logic in edge-triggered storage, state machine sequencing, and clock-domain synchronization where rail-to-rail voltage flexibility and SCR-latchup resistance are required.

Technical Context

The CD74AC74E implements two independent D-type flip-flops sharing no internal coupling - each responds solely to its dedicated CLK, D, PRE, and CLR signals. Clock triggering occurs on the positive-going edge at a defined voltage threshold, independent of input slew rate, with setup/hold times as low as 3.1 ns (VCC = 5 V) and recovery time of 2.4 ns after PRE/CLR deactivation.

Its AC CMOS process ensures balanced tPLH/tPHL propagation delays (e.g., 2.5–9.1 ns at 5 V), supports fanout to 15 F-family devices, and maintains functional stability across −55°C to +125°C via guaranteed timing over full temperature and voltage ranges - not just typical values.

Key Specifications

Pinout & Package

CD74AC74E uses a 14-pin plastic dual in-line package (PDIP-N), body size 19.3 mm × 6.35 mm, with 2.54 mm lead pitch and through-hole mounting compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AC74N, CD74AC74E adds extended temperature capability and identical AC performance; compared with CD74HC74E, it delivers 2× higher clock rate and 6× stronger output drive - making CD74AC74E optimal for high-reliability, high-speed synchronous logic where rail flexibility and noise immunity are critical.

Availability

CD74AC74E is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, automotive body control modules, and digital power supply sequencing requiring stable component supply across extended temperature and voltage ranges.

Supply support for CD74AC74E 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 company headquartered in Dallas, Texas, designing analog and embedded processing chips for industrial, automotive, and communications markets since 1930.

The CD74AC74E belongs to TI's advanced CMOS (AC) logic family, engineered for high-speed, low-power, and wide-voltage-operation digital building blocks used in robust timing, control, and data-path applications.

FAQ

What is the maximum clock frequency supported by the CD74AC74E?

The CD74AC74E supports a maximum clock frequency of 125 MHz when operated at VCC = 5 V ± 0.5 V across the −40°C to +85°C temperature range. At VCC = 3.3 V ± 0.3 V, the max frequency is 90 MHz, and at VCC = 1.5 V, it drops to 10 MHz. These values are guaranteed minimums per TI's SCHS231E datasheet Section 4.8–4.11.

Does the CD74AC74E require external pull-up or pull-down resistors on unused inputs?

Yes - all unused inputs of the CD74AC74E must be tied to either VCC or GND to prevent floating states that cause increased power consumption, logic instability, or ESD susceptibility. TI explicitly recommends this in Section 7.1.1 of the CD74AC74E datasheet, citing "Implications of Slow or Floating CMOS Inputs" (SCBA004).

Can the CD74AC74E operate reliably at 1.8 V supply voltage?

Yes - the CD74AC74E is fully specified for operation from 1.5 V to 5.5 V, including 1.8 V. At 1.8 V, it delivers guaranteed timing (e.g., fmax ≥ 20 MHz, tPLH ≤ 60 ns) and noise immunity of 0.54 V (30% of 1.8 V), making it suitable for mixed-voltage systems interfacing with 1.8 V microcontrollers or FPGAs.

What is the function of pins 1 and 13 on the CD74AC74E?

Pins 1 and 13 on the CD74AC74E are the active-low asynchronous clear (CLR) inputs for Channel 1 and Channel 2, respectively. When pulled low, each independently forces its corresponding Q output to logic low and Q̅ to logic high - overriding clock and data inputs. Both remain functional even when the other channel is active.

Is the CD74AC74E pin-compatible with the CD74HC74E?

Yes - the CD74AC74E and CD74HC74E share identical 14-pin PDIP (N) package dimensions, pin numbering, and pin functions. However, they differ electrically: CD74AC74E offers higher speed (125 MHz vs. 60 MHz), stronger drive (±24 mA vs. ±4 mA), and wider supply range (1.5–5.5 V vs. 2–6 V), so direct substitution requires validation of timing and loading requirements.