Texas Instruments SN74HCS240QPWRQ1

Overview

SN74HCS240QPWRQ1 from Texas Instruments is an automotive-grade octal inverting line driver IC with Schmitt-trigger inputs and 3-state outputs, operating across 2 V to 6 V supply. It delivers ±7.8-mA output drive at 6 V, features typical ICC of 100 nA, and supports AEC-Q100 Grade 1 (–40°C to +125°C) for engine control and body electronics signal conditioning.

For engineers reviewing the SN74HCS240QPWRQ1 datasheet, SN74HCS240QPWRQ1 pinout, SN74HCS240QPWRQ1 application, or SN74HCS240QPWRQ1 equivalent, key selection criteria include Schmitt-trigger noise immunity, dual-bank 3-state control (1OE/2OE), TSSOP-20 wettable-flank compatibility, and low-leakage CMOS logic performance in harsh automotive environments.

Technical Context

This device implements eight independent CMOS inverters grouped into two banks of four channels each, with separate active-low output enable pins (1OE, 2OE) controlling high-impedance state entry per bank. Each channel realizes Y = A̅ in positive logic.

Schmitt-trigger inputs provide hysteresis (ΔVT = 0.6 V min at 6 V), enabling robust operation with slow-rising or noisy signals; balanced CMOS 3-state outputs support bidirectional bus interfacing with ±7.8-mA sink/source capability at 6 V and <100 nA input leakage.

Key Specifications

Pinout & Package

SN74HCS240QPWRQ1 uses a 20-pin TSSOP (PW) package with 6.50 mm × 4.40 mm body size and wettable flanks for automated optical inspection (AOI) compatibility.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HCS240QPWRQ1, SN74HCS240PWRQ1 offers identical functionality in alternate packaging, while SN74LV240AQDRQ1 trades Schmitt-trigger noise rejection for higher speed and drive strength - making SN74HCS240QPWRQ1 the optimal choice for noisy automotive sensor interfaces where signal integrity outweighs raw bandwidth.

Availability

SN74HCS240QPWRQ1 is available at Aetrix Electronics and suitable for engine control units, body control modules, and instrument cluster designs requiring stable component supply across extended automotive temperature ranges and long production lifecycles.

Supply support for SN74HCS240QPWRQ1 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 and embedded processing technologies, with decades of automotive qualification expertise and broad AEC-Q100 product coverage.

The SN74HCS240QPWRQ1 belongs to TI's HCS logic family designed specifically for automotive signal conditioning - emphasizing ultra-low power, noise immunity, and extended temperature reliability in safety-critical electronic control systems.

FAQ

What is the maximum capacitive load SN74HCS240QPWRQ1 can drive while maintaining specified timing?

SN74HCS240QPWRQ1 is characterized for loads ≤50 pF per output, as defined in the Switching Characteristics section with CL = 50 pF. Driving larger capacitances increases propagation delay and transition time - for example, tpd rises from 6 ns (typ) at 50 pF to >15 ns at 100 pF. To maintain timing compliance in SN74HCS240QPWRQ1-based designs, keep trace+load capacitance at or below 50 pF unless re-characterized under actual conditions.

Does SN74HCS240QPWRQ1 require external pull-up resistors on its OE pins for safe power-up behavior?

Yes - to ensure outputs remain in high-impedance state during power-up/power-down, both 1OE and 2OE pins must be tied to VCC via pull-up resistors. TI recommends values ≥10 kΩ, sized to limit current based on driver capability and SN74HCS240QPWRQ1's input leakage (±100 nA max). This prevents bus contention in systems where downstream devices power up asynchronously with SN74HCS240QPWRQ1.

Can SN74HCS240QPWRQ1 outputs be paralleled to increase current drive capability?

Yes - two or more channels of SN74HCS240QPWRQ1 with identical inputs can be wired in parallel to double (or scale) output current drive, provided they belong to the same bank and share the same OE control. This technique is documented in TI's Application and Implementation section and maintains matched rise/fall times. However, do not parallel outputs across different banks or with mismatched inputs, as shoot-through current may occur.

Is the thermal pad in SN74HCS240QPWRQ1 electrically connected, and how should it be handled on PCB?

SN74HCS240QPWRQ1 uses a TSSOP-20 (PW) package without an exposed thermal pad - unlike the WRKS VQFN variant. Therefore, no thermal pad connection is required or possible. PCB layout should follow standard TSSOP guidelines: use thermal reliefs on GND/VCC pads, place 0.1-μF bypass capacitor within 3 mm of VCC–GND pins, and avoid floating inputs per TI's Layout Example in the datasheet.

How does the Schmitt-trigger input of SN74HCS240QPWRQ1 improve performance over standard CMOS inputs in automotive applications?

SN74HCS240QPWRQ1's Schmitt-trigger inputs provide 0.6 V minimum hysteresis at 6 V, allowing reliable recognition of slow-switching or EMI-corrupted signals - such as those from hall-effect sensors or mechanical switches - without oscillation or metastability. Unlike standard CMOS inputs, this architecture eliminates false toggling caused by noise near switching thresholds, reducing firmware debounce overhead and improving system-level reliability in harsh automotive environments where SN74HCS240QPWRQ1 is deployed.