Nexperia USA Inc. 74HCT7540D,112

Overview

74HCT7540D,112 from Nexperia is an octal inverting Schmitt-trigger buffer/line driver with 3-state outputs, dual active-low output enables (OE1, OE2), and TTL-compatible input thresholds. It operates from 4.5 V to 5.5 V, delivers ±6 mA output drive at VCC = 4.5 V, and supports industrial temperature range (−40 °C to +125 °C) in SO20 (SOT163-1) package. Used for noise-immune signal conditioning and bus interface in industrial control I/O modules.

For engineers reviewing the 74HCT7540D,112 datasheet, 74HCT7540D,112 pinout, 74HCT7540D,112 application, or 74HCT7540D,112 equivalent, key selection criteria include Schmitt-trigger hysteresis (0.23 V typ), propagation delay (19 ns typ @ 4.5 V), 3-state enable/disable timing (32 ns typ), TTL-level input compatibility, and SO20 thermal derating (12.3 mW/K above 109 °C).

Technical Context

This device implements dual independent 3-state controls (OE1 and OE2) enabling flexible bus arbitration-either enable can place all eight outputs into high-impedance state. Its Schmitt-trigger inputs provide 0.23 V typical hysteresis at VCC = 4.5 V, rejecting slow-rising noise on industrial sensor lines.

The logic function is strictly inverting: each Yn output is the complement of its corresponding An input when enabled. Input clamp diodes allow safe interfacing to voltages exceeding VCC when used with current-limiting resistors-critical for mixed-voltage system backplane designs.

Key Specifications

Pinout & Package

74HCT7540D,112 is housed in a plastic small outline package (SO20, SOT163-1) with 20 leads and 7.5 mm body width. Thermal derating begins at 109 °C (12.3 mW/K).

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HCT240D,653, the 74HCT7540D,112 adds essential noise immunity for field-deployed systems; versus SN74HCT541PWR, it offers superior thermal stability in convection-cooled enclosures due to SO20's higher thermal mass and derating threshold.

Availability

74HCT7540D,112 is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automated test equipment signal paths, motor drive interface boards, and legacy system bus extensions requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74HCT7540D,112 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

Nexperia is a global semiconductor expert delivering high-performance logic, discrete, and MOSFET solutions optimized for efficiency, reliability, and manufacturability in industrial and automotive applications.

The 74HCT7540 belongs to Nexperia's high-reliability HC/HCT logic family, engineered specifically for noise-prone industrial control environments requiring robust signal conditioning, wide operating margins, and long-term supply assurance.

FAQ

What is the maximum clock frequency supported by 74HCT7540D,112?

The 74HCT7540D,112 is not a clocked device-it has no internal clock and operates asynchronously. Its usable signal frequency is determined by propagation delay (19 ns typ) and load capacitance. With 50 pF load, it reliably handles edge rates up to ~25 MHz; for slower signals (<1 MHz), its Schmitt-trigger inputs provide superior noise rejection without timing constraints.

Can OE1 and OE2 be tied together for single-enable operation?

Yes-OE1 and OE2 may be connected to a common control signal. Both are active-low and electrically identical; tying them simplifies PCB routing and reduces GPIO usage. No additional pull-up or logic is required, and the combined enable retains full 3-state functionality across all eight outputs.

Does 74HCT7540D,112 support mixed-voltage operation (e.g., 3.3 V inputs driving a 5 V supply)?

No-the 74HCT7540D,112 requires VCC = 4.5–5.5 V and has TTL-level inputs designed for 5 V systems. Inputs exceeding VCC by more than 0.5 V risk damage unless current-limited via external resistors. For 3.3 V-to-5 V interfacing, use a dedicated level translator or the 74LVC series instead.

How does the Schmitt-trigger input improve performance in relay interface applications?

In relay feedback circuits, mechanical contact bounce generates multiple rapid transitions. The 74HCT7540D,112's 0.23 V hysteresis prevents retriggering during bounce windows (typically 1–10 ms), ensuring only one clean logic edge per relay closure-eliminating software debouncing and reducing MCU interrupt load by >95%.