Texas Instruments SN74HCS74QBQARQ1

Overview

SN74HCS74QBQARQ1 from Texas Instruments is an automotive-grade dual D-type positive-edge-triggered flip-flop with Schmitt-trigger inputs, asynchronous preset and clear, 2 V–6 V supply operation, ±7.8-mA output drive at 6 V, and AEC-Q100 Grade 1 qualification (–40°C to +125°C). It functions as a noise-immune edge-sensitive storage element in vehicle body control modules and power management sequencers.

For engineers reviewing the SN74HCS74QBQARQ1 datasheet, SN74HCS74QBQARQ1 pinout, SN74HCS74QBQARQ1 application, or SN74HCS74QBQARQ1 equivalent, key selection criteria include Schmitt-trigger hysteresis (ΔVT = 0.6–1.6 V), propagation delay (7–42 ns), low ICC (0.1–2 µA), dual-channel independence, and WQFN-14 package thermal performance (RθJB = 77.9°C/W).

Technical Context

This device implements two fully independent CMOS D-type flip-flops, each with asynchronous active-low PRE and CLR inputs and Schmitt-triggered CLK/D inputs. Clock triggering occurs on the positive-going edge at defined voltage thresholds-not dependent on input slew rate-enabling reliable operation with slow or noisy signals.

All inputs feature hysteresis (ΔVT up to 1.6 V at 6 V), and outputs deliver balanced push-pull drive (±7.8 mA at 6 V) with VOH ≥ 5.4 V and VOL ≤ 0.33 V under full load. The device operates across 2 V–6 V with guaranteed timing down to –40°C and up to +125°C ambient.

Key Specifications

Pinout & Package

SN74HCS74QBQARQ1 uses a 14-pin WQFN package (3.00 mm × 2.50 mm, 0.5-mm pitch) with exposed thermal pad. The pad may be connected to GND or left floating-never tied to signal or supply nets.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCS74QBQARQ1, the SOIC-packaged SN74HCS74DQ1 trades thermal efficiency for legacy compatibility, while MC74HC74ADTR2G omits automotive qualification - making SN74HCS74QBQARQ1 the only option meeting full Grade 1 thermal, ESD, and reliability requirements in compact WQFN form.

Availability

SN74HCS74QBQARQ1 is available at Aetrix Electronics and suitable for automotive body control, power sequencing, ADAS sensor management, and infotainment clocking applications requiring stable component supply across extended temperature and long production lifecycles.

Supply support for SN74HCS74QBQARQ1 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 automotive electronics, with decades of automotive qualification expertise and broad foundry partnerships.

SN74HCS74QBQARQ1 belongs to TI's HCS logic family - designed specifically for automotive signal integrity, low-power operation, and robust noise immunity in electrically harsh vehicle environments.

FAQ

What is the maximum clock frequency supported by SN74HCS74QBQARQ1?

SN74HCS74QBQARQ1 supports a maximum switching frequency of 105 MHz at 6 V supply and 25°C, with guaranteed minimum fmax of 65 MHz across the full –40°C to +125°C operating range. This enables reliable clock division and signal synchronization in high-speed automotive subsystems such as display interfaces and sensor data acquisition paths.

Does SN74HCS74QBQARQ1 require external pull-up or pull-down resistors on unused inputs?

Yes - all unused inputs on SN74HCS74QBQARQ1 must be terminated to either VCC or GND to prevent floating states and undefined logic behavior. A 10-kΩ resistor is recommended for most cases, balancing leakage current (±100 nA), drive capability, and transition speed. Schmitt-trigger inputs eliminate slew-rate constraints but do not remove the need for DC biasing.

Can SN74HCS74QBQARQ1 operate reliably with slow-rising input signals from mechanical switches?

Yes - SN74HCS74QBQARQ1's Schmitt-trigger inputs provide 0.6–1.6 V hysteresis, enabling robust operation with input rise times up to 100 µs. This eliminates external RC debounce networks when interfacing with dashboard buttons, door latch sensors, or ignition switches - verified in TI's typical application circuit (Figure 9-1).

What is the thermal pad connection requirement for SN74HCS74QBQARQ1's WQFN package?

The thermal pad on SN74HCS74QBQARQ1's WQFN package may be connected to GND or left electrically floating - it must never be connected to VCC or any signal net. TI specifies this in the Pin Functions table; connecting to GND improves thermal resistance (RθJB = 77.9°C/W), while floating retains full functionality with slightly reduced thermal performance.

How does SN74HCS74QBQARQ1 differ from standard SN74HC74 in automotive applications?

SN74HCS74QBQARQ1 adds Schmitt-trigger inputs (vs. standard CMOS inputs on SN74HC74), AEC-Q100 Grade 1 qualification (–40°C to +125°C), and enhanced ESD ratings (HBM ±4 kV, CDM ±1.5 kV). These features make SN74HCS74QBQARQ1 suitable for direct switch/sensor interfacing in harsh automotive environments where SN74HC74 would require external signal conditioning and lacks formal automotive qualification.