Texas Instruments SN74HCS244QWRKSRQ1

Overview

SN74HCS244QWRKSRQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive octal buffer with Schmitt-trigger inputs and 3-state outputs, configured as two independent 4-channel banks each controlled by dedicated active-low output enable pins. It operates from 2 V to 6 V, delivers ±7.8 mA output drive at 6 V, and draws only 100 nA typical supply current - enabling robust signal conditioning in noisy engine control or body electronics modules.

For engineers reviewing the SN74HCS244QWRKSRQ1 datasheet, SN74HCS244QWRKSRQ1 pinout, SN74HCS244QWRKSRQ1 application, or SN74HCS244QWRKSRQ1 equivalent, key selection criteria include its wettable-flank VQFN (WRKS) package for AOI-compatible solder joint inspection, Schmitt-trigger noise immunity on all eight inputs, dual-bank 3-state control for bus isolation, and guaranteed operation from –40°C to +125°C ambient.

Technical Context

The SN74HCS244QWRKSRQ1 implements two independent 4-bit non-inverting buffer banks, each with dedicated active-low output enable (1OE/2OE), enabling selective bus driving or isolation without contention. Its Schmitt-trigger inputs provide hysteresis (ΔVT = 0.6 V min at 6 V), allowing reliable logic-level detection of slow-rising signals or rejection of noise up to ±300 mV peak-to-peak.

Each output features balanced CMOS push-pull structure capable of sourcing/sinking ±7.8 mA at 6 V while maintaining VOH ≥ 5.4 V and VOL ≤ 0.33 V. The device uses standard CMOS process technology with input leakage ≤ ±100 nA and ICC ≤ 2 µA max across temperature, supporting ultra-low-power always-on subsystems.

Key Specifications

Pinout & Package

VQFN-20 (WRKS) package with wettable flanks, 4.50 mm × 2.50 mm body size, exposed thermal pad (connectable to GND or left floating).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal buffer applications.

Compared with SN74HCS244PWRQ1 and MC74HC244ADTR2G, the SN74HCS244QWRKSRQ1 uniquely combines wettable-flank manufacturability, AEC-Q100 Grade 1 qualification, and lowest thermal resistance among pin-compatible octal buffers - making it optimal for high-reliability, high-volume automotive control units requiring zero-defect solder joint assurance.

Availability

SN74HCS244QWRKSRQ1 is available at Aetrix Electronics and suitable for engine control units, body control modules, infotainment displays, and transmission control units requiring stable component supply across automotive production lifecycles.

Supply support for SN74HCS244QWRKSRQ1 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 designing analog and embedded processing chips for industrial, automotive, and consumer applications, with leadership in precision analog and high-reliability logic solutions.

The SN74HCS244QWRKSRQ1 belongs to TI's automotive-qualified HCS logic family, engineered specifically for noise-immune signal buffering in harsh-EMI vehicle environments where Schmitt-trigger inputs and AEC-Q100 compliance are mandatory.

FAQ

What is the maximum capacitive load the SN74HCS244QWRKSRQ1 can drive while meeting all datasheet specifications?

The SN74HCS244QWRKSRQ1 is characterized for CL = 50 pF in its switching characteristics table. While larger loads may be driven, TI specifies that operation with total output capacitance ≤ 50 pF ensures guaranteed tpd, ten, tdis, and tt performance across voltage and temperature. Exceeding this value increases propagation delay and may degrade edge fidelity, especially at 6 V supply.

Does the SN74HCS244QWRKSRQ1 require external pull-up resistors on its output enable pins?

Yes - to ensure outputs remain in high-impedance state during power-up or power-down, both 1OE and 2OE pins should be tied to VCC via pull-up resistors. TI recommends sizing based on driver sink capability and pin leakage (≤ ±100 nA); a 10-kΩ resistor is commonly used and compatible with most microcontroller GPIOs. The SN74HCS244QWRKSRQ1 itself does not integrate internal pull-ups.

Can unused inputs on the SN74HCS244QWRKSRQ1 be left floating?

No - unused inputs must be terminated to either VCC or GND. Although Schmitt-trigger inputs tolerate slow transitions, floating nodes create undefined logic states, increase susceptibility to EMI-induced glitches, and may elevate ICC due to intermediate biasing. TI explicitly requires termination in Section 9.2.1.2; a 10-kΩ pull-up or pull-down resistor is recommended for unused 1A/2A pins.

Is the thermal pad on the SN74HCS244QWRKSRQ1 package required to be connected to ground?

No - the thermal pad (exposed copper on bottom of WRKS package) may be connected to GND or left electrically floating. TI states it must not be connected to any other signal or supply. Connecting to GND improves thermal performance (reducing RθJB), but floating is acceptable if board layout constraints prohibit grounding; thermal pad connection has no effect on electrical functionality.

What is the minimum output load resistance the SN74HCS244QWRKSRQ1 can safely drive at 6 V supply?

Based on VOH ≥ 5.4 V and IOH = –7.8 mA (min), the minimum safe load resistance is RL ≥ (6 V – 5.4 V) / 7.8 mA ≈ 77 Ω. For VOL ≤ 0.33 V and IOL = 7.8 mA, RL ≥ 0.33 V / 7.8 mA ≈ 42 Ω. Therefore, a conservative design limit is RL ≥ 77 Ω to maintain both VOH and VOL specs simultaneously at full drive strength. Higher resistances are preferred for logic interfacing.