Texas Instruments SN74HCS240QWRKSRQ1

Overview

SN74HCS240QWRKSRQ1 from Texas Instruments is an automotive-qualified octal inverting line driver IC with Schmitt-trigger inputs and 3-state outputs, operating from 2 V to 6 V supply. It features ±7.8-mA output drive at 6 V, 100 nA typical ICC, and AEC-Q100 Grade 1 qualification (–40°C to +125°C). It enables signal gating and noise-immune buffering in vehicle body control modules.

For engineers reviewing the SN74HCS240QWRKSRQ1 datasheet, SN74HCS240QWRKSRQ1 pinout, SN74HCS240QWRKSRQ1 application, or SN74HCS240QWRKSRQ1 equivalent, key selection criteria include Schmitt-trigger hysteresis (ΔVT ≥ 0.6 V at 6 V), dual-bank 3-state control (1OE/2OE), wettable-flank VQFN-20 package compatibility, and automotive thermal reliability (RθJA = 83.2°C/W).

Technical Context

This device implements eight independent CMOS inverters grouped into two banks of four, each controlled by a dedicated active-low output enable (1OE or 2OE). Each channel performs Y = A̅ in positive logic, with Schmitt-trigger inputs providing hysteresis (VT+ − VT−) up to 1.6 V at 6 V for robust noise rejection.

The balanced CMOS 3-state outputs support bidirectional current sourcing/sinking (±7.8 mA at 6 V) and enter high-impedance when OE is high. Input leakage remains ≤ ±1000 nA at 6 V, and propagation delay is as low as 6 ns at 6 V with CL = 50 pF.

Key Specifications

Pinout & Package

SN74HCS240QWRKSRQ1 uses a 20-pin wettable-flank VQFN (WRKS) package measuring 4.50 mm × 2.50 mm with exposed thermal pad. The wettable flanks support automated optical inspection (AOI) of solder fillets during SMT reflow.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCS240PWQ1 and MC74HC240ADTR2G, SN74HCS240QWRKSRQ1 uniquely combines wettable-flank manufacturability, Grade 1 thermal rating, and verified 125°C operation - making it the sole option qualified for under-hood power distribution and chassis domain controllers.

Availability

SN74HCS240QWRKSRQ1 is available at Aetrix Electronics and suitable for automotive body control modules, switch debounce interfaces, instrument cluster backlight drivers, and ADAS power sequencing requiring stable component supply across extended temperature ranges.

Supply support for SN74HCS240QWRKSRQ1 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-grade logic solutions with over 50 years of industry experience.

SN74HCS240QWRKSRQ1 belongs to TI's HCS logic family designed specifically for automotive signal conditioning - emphasizing low power, noise immunity, and AEC-Q100-compliant reliability in harsh environments.

FAQ

What is the maximum capacitive load SN74HCS240QWRKSRQ1 can drive while meeting datasheet timing specs?

SN74HCS240QWRKSRQ1 is characterized for CL ≤ 50 pF in switching specifications (tpd, ten, tdis). Driving larger loads increases propagation delay and transition time - for example, at 100 pF, tpd rises ~30% at 6 V. To maintain timing integrity in high-speed control loops, keep total node capacitance (trace + receiver input + probe) at or below 50 pF. SN74HCS240QWRKSRQ1 datasheet Figure 6-3 confirms stable ICC up to 100 pF, but timing margins degrade beyond 50 pF.

How should unused inputs be terminated on SN74HCS240QWRKSRQ1?

All unused inputs on SN74HCS240QWRKSRQ1 must be tied to a valid logic level - either VCC or GND - to prevent floating states that cause excessive current draw and logic instability. A 10-kΩ pull-up or pull-down resistor is recommended per Electrical Characteristics (II ≤ ±1000 nA at 6 V), balancing leakage control and board space. Direct connection is acceptable if the input is permanently unused; resistive termination is preferred when future reconfiguration is possible. SN74HCS240QWRKSRQ1 layout guidelines explicitly prohibit leaving inputs unconnected.

Does SN74HCS240QWRKSRQ1 support hot insertion or live swapping in powered systems?

SN74HCS240QWRKSRQ1 is not designed for hot insertion. Its absolute maximum ratings specify VI limits of –0.5 V to VCC + 0.5 V; applying voltage to inputs or outputs before VCC ramps violates this condition and risks damage via internal clamp diodes. During power-up, both OE pins should be pulled to VCC to ensure outputs remain in high-Z until supply stabilizes. SN74HCS240QWRKSRQ1 does not include power-on reset circuitry or Ioff protection - hot-swap capability requires external sequencing or buffer isolation.

Can SN74HCS240QWRKSRQ1 outputs be paralleled for higher drive strength?

Yes - SN74HCS240QWRKSRQ1 outputs with identical inputs (e.g., 1Y1 and 1Y2 driven by same 1A1 signal) can be safely paralleled to double sink/source current capacity. This is explicitly supported in Section 9.2.1.3 of the datasheet. Ensure matched trace lengths and identical OE states; do not parallel outputs from different banks or with differing input signals, as contention could exceed ±35 mA absolute maximum output current and damage the device. SN74HCS240QWRKSRQ1's balanced CMOS outputs make this configuration electrically robust when implemented correctly.

What is the purpose of the thermal pad on the SN74HCS240QWRKSRQ1 WRKS package?

The exposed thermal pad on SN74HCS240QWRKSRQ1's WRKS package reduces junction-to-board thermal resistance (RθJB = 57.4°C/W) and improves power dissipation during sustained operation at high ambient temperatures. It may be connected to GND plane for enhanced electrical and thermal performance, or left floating - but must never connect to any signal or supply other than GND. TI's layout example shows direct GND connection; doing so lowers steady-state junction temperature by ~15°C at 125°C ambient, directly supporting AEC-Q100 Grade 1 reliability. SN74HCS240QWRKSRQ1 thermal metrics confirm this pad is integral to meeting automotive thermal requirements.