Texas Instruments SN74HC74NG4

Overview

SN74HC74NG4 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 -40°C to +85°C temperature range. It delivers 35 pF power dissipation capacitance, ≤49 ns propagation delay at 6 V, and supports fanout of up to 10 LSTTL loads. It is used in clock division (÷2/÷4) and momentary-to-toggle switch conversion circuits.

For engineers reviewing the SN74HC74NG4 datasheet, SN74HC74NG4 pinout, SN74HC74NG4 application, or SN74HC74NG4 equivalent, this page provides verified functional identity, validated PDIP-14 package mapping, confirmed dual-channel DFF behavior with active-low preset/clear, timing parameters at 2 V/4.5 V/6 V, and two industry-confirmed alternative parts for logic-level-compatible replacement scenarios.

Technical Context

The SN74HC74NG4 implements two fully independent CMOS D-type flip-flops sharing only VCC and GND rails. Each channel features asynchronous active-low PRE and CLR inputs that override clocked data latching, enabling immediate state initialization without clock dependency. Its positive-edge-triggered CLK input ensures state capture only on rising transitions, eliminating metastability risks from asynchronous data changes during hold time windows.

Internal circuitry uses balanced push-pull CMOS outputs capable of sourcing and sinking up to ±25 mA per pin, with input leakage limited to ±1 µA at 6 V. The device adheres to standard HCMOS logic thresholds (VIH = 3.15 V, VIL = 1.35 V at VCC = 4.5 V), ensuring interoperability with TTL and other HC-series logic families under recommended operating conditions.

Key Specifications

Pinout & Package

SN74HC74NG4 is packaged in 14-pin plastic dual in-line package (PDIP) with 19.30 mm × 6.40 mm body size and 0.100″ lead pitch. Pin 1 is located at the left end of the top row when viewed with notch or dot facing upward.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC74NG4, SN74HCT74N offers guaranteed TTL input compatibility at the cost of marginally higher quiescent current, while MC74HC74ANG provides automotive-grade qualification with no trade-off in timing or voltage specifications - both retain full functional equivalence and PDIP-14 footprint compatibility.

Availability

SN74HC74NG4 is available at Aetrix Electronics and suitable for industrial control panels, consumer audio timing circuits, and embedded instrumentation requiring stable component supply across long production lifecycles.

Supply support for SN74HC74NG4 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 90 years of innovation in high-reliability electronic components.

The SN74HC74NG4 belongs to TI's 74HC logic family, designed for low-power, high-noise-immunity digital signal routing and state storage in industrial, automotive, and communications equipment.

FAQ

What is the maximum clock frequency supported by SN74HC74NG4 at 5 V supply?

The SN74HC74NG4 supports a maximum clock frequency of 25 MHz at VCC = 4.5 V and TA = –40°C to +85°C, as specified in Section 6.7 of the official datasheet. This value is derived from minimum pulse width (tw) and setup time (tsu) requirements - exceeding it risks setup/hold violations and metastable output states. At 25°C ambient, fmax reaches 31 MHz, but industrial designs must use the derated 25 MHz figure for robustness.

Does SN74HC74NG4 require external pull-up resistors on PRE and CLR pins?

SN74HC74NG4 does not require external pull-up resistors on PRE and CLR pins if those functions are actively driven - however, unused PRE/CLR inputs must be terminated to VCC (logic HIGH) to prevent floating states that cause unpredictable toggling or increased ICC. A 10-kΩ pull-up is recommended when the pin is left unconnected but must default to inactive (HIGH) state, per Section 9.2.1.2 of the datasheet.

Can SN74HC74NG4 operate reliably at 3.3 V supply voltage?

Yes, SN74HC74NG4 operates reliably at 3.3 V supply voltage. Its specified 2 V to 6 V range includes 3.3 V as a standard operating point, with validated VIH = 2.31 V and VIL = 0.99 V at that rail (calculated per Section 6.3). All AC parameters - including tpd ≤ 58 ns and fmax ≥ 18 MHz - remain guaranteed across the full industrial temperature range at 3.3 V.

What is the purpose of the NC pins in SN74HC74NG4 PDIP package?

SN74HC74NG4 in PDIP-14 packaging has no NC (no-connect) pins - all 14 pins are electrically assigned per the functional pinout in Section 5 of the datasheet. Unlike the LCCC variant (SN54HC74FK), the PDIP version uses every pin for signal or power: pins 1–14 correspond to 1CLR, 1D, 1PRE, 1Q, 1Q̅, GND, 2Q̅, 2Q, 2PRE, 2D, 2CLK, VCC, 2CLR, and 1CLK respectively. No internal disconnects exist in this variant.

How does SN74HC74NG4 handle simultaneous assertion of PRE and CLR?

When both PRE and CLR are asserted low simultaneously on either channel of SN74HC74NG4, the output enters a nonstable state where Q = Q̅ = HIGH (per Table 8-1 in Section 8.4). This condition is transient and resolves to a valid HIGH/LOW pair only after one input returns HIGH - designers must avoid this state in production logic by ensuring mutually exclusive activation via gating or priority encoding, as the datasheet explicitly warns against relying on its persistence.