Texas Instruments CD74HC74E-NG

Overview

CD74HC74E-NG from Texas Instruments is a dual D-type positive-edge-triggered flip-flop with independent asynchronous clear and preset inputs per channel, operating across 2 V to 6 V supply, supporting –55°C to +125°C industrial/military temperature range, and delivering ≤45 ns propagation delay at 6 V with 50 pF load - used in clock division and momentary-to-toggle switch conversion.

For engineers reviewing the CD74HC74E-NG datasheet, CD74HC74E-NG pinout, CD74HC74E-NG application, or CD74HC74E-NG equivalent, key selection criteria include dual-channel edge-triggered storage, rail-to-rail CMOS-compatible I/O, guaranteed timing at extended temperature, and PDIP-14 package compatibility with through-hole prototyping and legacy industrial control PCBs.

Technical Context

This device implements two fully independent D-type latches synchronized to the rising edge of their respective clock inputs, each with active-low asynchronous set (PRE) and reset (CLR) that override clock and data states. Its balanced CMOS push-pull outputs source/sink up to ±25 mA while maintaining VOH ≥5.48 V and VOL ≤0.4 V at 6 V/5.2 mA.

The CD74HC74E-NG uses standard CMOS inputs with 10 pF typical input capacitance and requires input transition times ≤400 ns at 6 V to prevent shoot-through current; its function table confirms non-overlapping PRE/CLR priority and metastability-free toggling when Q̅ is fed back to D.

Key Specifications

Pinout & Package

CD74HC74E-NG is housed in a 14-pin plastic dual in-line package (PDIP-N), 19.30 mm × 6.40 mm body size, through-hole mountable with 2.54 mm pin pitch and NIPDAU lead finish compliant with RoHS.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC74N and MC74HC74ANG, the CD74HC74E-NG provides superior high-temperature operation and lower thermal resistance, making it the preferred choice for mission-critical systems requiring guaranteed functionality beyond 85°C and tighter thermal management.

Availability

CD74HC74E-NG is available at Aetrix Electronics and suitable for industrial control panels, aerospace sensor interfaces, and military communications equipment requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CD74HC74E-NG 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 specializing in analog and embedded processing technologies, with leadership in high-reliability logic, precision analog, and power management ICs.

The CD74HC74E-NG belongs to TI's HC logic family designed for low-power, wide-voltage, extended-temperature digital interfacing - targeting industrial automation, defense systems, and space-constrained instrumentation where robustness and longevity are mandatory.

FAQ

What is the maximum clock frequency supported by CD74HC74E-NG at 5 V supply?

The CD74HC74E-NG supports a maximum clock frequency of 25 MHz at 5 V supply voltage, as specified in the switching characteristics table under recommended operating conditions. This value is guaranteed across the full –55°C to +125°C temperature range and accounts for worst-case propagation delay (tpd ≤ 44 ns) and setup/hold timing margins. Operation above this frequency may result in metastability or incorrect state capture.

Does CD74HC74E-NG require external pull-up resistors on PRE and CLR pins?

Yes, CD74HC74E-NG requires external pull-up resistors (typically 10 kΩ) on both PRE and CLR pins when not actively driven low, because these inputs are active-low and internally unconnected. Leaving them floating risks undefined output states due to noise coupling or leakage-induced threshold crossing. The CD74HC74E-NG datasheet explicitly mandates termination to VCC or GND for all unused inputs.

Can CD74HC74E-NG drive a 50 pF capacitive load while meeting timing specifications?

Yes, CD74HC74E-NG is fully characterized for 50 pF capacitive loads: its propagation delay (tpd), setup time (tsu), and hold time (th) values in Section 6.6 and 6.5 are all measured under CL = 50 pF conditions. The device maintains tpd ≤ 44 ns and tsu ≥ 15 ns at 4.5 V, ensuring reliable operation in standard PCB trace environments without added series termination.

Is CD74HC74E-NG compatible with 3.3 V microcontroller GPIOs?

Yes, CD74HC74E-NG is compatible with 3.3 V microcontroller GPIOs: its VIH threshold is 2.0 V min at 3.3 V supply (per Section 6.2), and its VOL remains ≤0.33 V at 4 mA sink current, ensuring clean LOW recognition. The CD74HC74E-NG also tolerates 3.3 V inputs when operated at 5 V supply, satisfying overvoltage-tolerant interface requirements.

What is the thermal resistance (RθJA) of CD74HC74E-NG in its PDIP package?

The junction-to-ambient thermal resistance (RθJA) of CD74HC74E-NG in its PDIP-14 package is 62.2°C/W, as documented in Section 6.3 of the datasheet. This value assumes standard JEDEC 2-layer board mounting and reflects the device's ability to dissipate heat under natural convection; actual board layout, copper area, and airflow will affect real-world thermal performance.