Texas Instruments CD74HCT112E

Overview

CD74HCT112E from Texas Instruments is a dual J-K flip-flop with asynchronous set and reset, negative-edge clock triggering, complementary Q/Q outputs, and buffered inputs. It operates at 4.5 V to 5.5 V, supports 60 MHz maximum clock frequency at 5 V/15 pF, delivers 4 mA output drive, and functions across –55°C to +125°C for industrial and aerospace timing control.

For engineers reviewing the CD74HCT112E datasheet, CD74HCT112E pinout, CD74HCT112E application, or CD74HCT112E equivalent, this page provides verified functional behavior, validated thermal and switching specifications, confirmed PDIP-16 package mapping, and real-world design context for synchronous logic state storage in noise-immune digital systems.

Technical Context

The CD74HCT112E implements two independent edge-triggered J-K bistable multivibrators using silicon-gate CMOS technology. Each section features separate J, K, PRE (asynchronous preset), CLR (asynchronous clear), and CLK inputs, with complementary Q and Q̅ outputs that change state on the negative-going transition of CLK.

It is functionally and pin-compatible with LS-TTL logic families, accepts LSTTL input voltage levels (VIL ≤ 0.8 V, VIH ≥ 2.0 V), exhibits hysteresis on clock inputs for noise immunity, and maintains balanced propagation delays (tPLH/tPHL ≤ 53 ns max at –55°C to +125°C, VCC = 4.5 V) and transition times (tTLH/tTHL ≤ 22 ns).

Key Specifications

Pinout & Package

CD74HCT112E is supplied in a 16-pin Plastic Dual In-line Package (PDIP), body size 19.31 mm × 6.35 mm, with standard through-hole mounting and 2.54 mm pin pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCT112N and 74HCT112D, CD74HCT112E offers identical logic functionality and timing but uniquely supports through-hole assembly via its PDIP-16 package - critical for field repair, lab validation, and legacy board compatibility where SOIC or reel-based variants cannot be substituted without hardware modification.

Availability

CD74HCT112E is available at Aetrix Electronics and suitable for industrial PLC timing modules, digital test equipment counters, and aerospace avionics sequencers requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HCT112E 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 delivering analog and embedded processing solutions, with over 90 years of innovation in logic, power management, and signal chain technologies.

The CD74HCT112E belongs to TI's legacy HCT logic family, designed specifically to provide TTL-compatible CMOS alternatives for industrial, military, and aerospace applications demanding wide temperature operation and noise-immune digital sequencing.

FAQ

What is the maximum clock frequency supported by CD74HCT112E?

The CD74HCT112E supports a maximum clock frequency of 60 MHz under nominal conditions (VCC = 5 V, CL = 15 pF, TA = 25°C). At full temperature range (–55°C to +125°C) and VCC = 4.5 V, the guaranteed fMAX is 20 MHz per the switching characteristics table. This makes CD74HCT112E suitable for medium-speed synchronous logic where deterministic timing and wide-temperature stability are required.

Does CD74HCT112E require external pull-up or pull-down resistors on unused inputs?

Yes, CD74HCT112E requires all unused inputs (J, K, PRE, CLR, CLK) to be tied to a defined logic level - either VCC or GND - as floating inputs can cause undefined output states, increased power consumption, or oscillation. The device does not include internal pull resistors; TI's layout guidelines explicitly mandate termination of all unused logic inputs to prevent operational instability.

Is CD74HCT112E pin-compatible with the older 74LS112?

Yes, CD74HCT112E is functionally and pin-compatible with the 74LS112. Both devices use the same 16-pin PDIP package and identical pin assignments for J, K, CLK, PRE, CLR, Q, and Q̅. The CD74HCT112E maintains LSTTL input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V), enabling direct replacement without circuit modification - a key design advantage for legacy system upgrades.

What is the purpose of hysteresis on the clock inputs of CD74HCT112E?

Hysteresis on the CD74HCT112E clock inputs improves noise immunity by introducing a voltage threshold gap between rising and falling edge detection. This prevents false triggering from slow-rising or noisy clock signals and relaxes input rise/fall time requirements to ≤1 ms. It directly enhances reliability in electrically noisy industrial or automotive environments where clock integrity cannot be guaranteed.

Can CD74HCT112E operate from a 3.3 V supply?

No, CD74HCT112E is not rated for 3.3 V operation. Its recommended supply voltage range is strictly 4.5 V to 5.5 V, as defined in the HCT family specification. Operating below 4.5 V may result in invalid logic thresholds, reduced noise margin, or failure to meet timing parameters. For 3.3 V systems, consider the HC-family variant CD74HC112E (2–6 V) or dedicated 3.3 V logic families.