Logic family numbering: In 54/74-series logic ICs, the “54” prefix denotes an extended (military) operating temperature range compared to the “74” commercial range. Is this statement accurate?

Introduction / Context:
Classic logic families are identified by series numbers such as 54xx and 74xx. Understanding the differences helps engineers select parts that will operate reliably across required environmental conditions, especially in aerospace and defense applications.

Given Data / Assumptions:

• 54-series devices are qualified for extended temperature ranges.
• 74-series devices are targeted at commercial/industrial ranges depending on suffix.
• The underlying logic family (TTL, CMOS derivatives) can exist under both prefixes.

Concept / Approach:
The “54” prefix historically indicates military-grade temperature specifications (for example, approximately −55 °C to +125 °C), tighter screening, and sometimes different packaging options. The “74” series typically denotes commercial or industrial temperature ranges depending on specific family variants and manufacturer datasheets.

Step-by-Step Solution:

Verification / Alternative check:
Cross-reference vendor datasheets: 54HCxx or 54LSxx lines list wider temperature specs versus 74HCxx or 74LSxx commercial counterparts, validating the role of the prefix.

Why Other Options Are Wrong:

• Incorrect/Only for CMOS/Only for high-speed/Only for plastic: The prefix denotes qualification range regardless of whether the family is TTL or CMOS and is not bound to speed grade or package type alone.

Common Pitfalls:
Equating “74” exclusively with commercial 0–70 °C without noting industrial variants; overlooking the fact that both prefixes can cover multiple sub-families with different electrical characteristics.

Final Answer:
Correct