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Harmonizing Circuit Design and EMC Design

Part 4  Product Specifications (1)
Product Specifications of Semiconductor Integrated Circuits

Specification Essentials and Statements Relating to EMC

Good day! Inagaki of ROHM here.

In Part 4, we describe semiconductor integrated circuit product specifications. The phrase "semiconductor integrated circuit product specifications" may sound rather pretentious, but it is perhaps more often known as an "IC datasheet". It is absolutely necessary when using an IC, and of course design is not possible without the spec information. However, it cannot be said that an engineer always necessarily understands absolutely everything up to and including the finest details of the datasheet. In this column, I'd like to talk about some of the essentials of the specifications, parts of the datasheet that need to be emphasized.

ROHM product specifications are generally written in the following order: product name, part number, general description, features, applications, key specifications, package, typical application circuits, pin configuration, pin description, block diagram, description of blocks, absolute maximum ratings, thermal resistance, recommended operating conditions, description of functions, electrical characteristics, typical performance curves, application examples, I/O equivalence circuits, operational notes, ordering information, marking diagram, physical dimension and packing information, revision history, and notice.

Among these, the absolute maximum ratings, recommended operating conditions, and electrical characteristics are especially important.

The first of these, absolute maximum ratings, are of course the maximum values of electrical rated values; if a voltage, current, or the like exceeding these values even for an instant is applied, device operation is not guaranteed. They are the maximum values up until which the semiconductor IC device is guaranteed not to be damaged or to fail. Apart from voltages and currents, these absolute maximum ratings also include values for the maximum junction temperature and storage temperature.

The second of these, the recommended operating conditions, describes conditions such as the power supply voltage and input/output needed to most effectively exploit the performance of the semiconductor integrated circuit. The semiconductor IC is designed assuming that it will be operated under these conditions, and so as a rule, the device should be operated under the conditions described.

The third category, electrical characteristics, are the most important, as they indicate the guaranteed characteristics of the semiconductor integrated circuit. All the guaranteed values appearing on the datasheet are warranted as correct. Inspections are performed before shipping to ensure that guaranteed values, and mainly the typical values of the different characteristics, are satisfied. During product design, the electrical design must be performed so as to ensure that the device operates normally with electrical characteristics within the guaranteed values.

Well then, how is electromagnetic compatibility (EMC) related? In many cases, information related to EMC appears on the top page of the product specifications. This is, to be specific, such information as "AEC-Q100 compatible", "highly EMI tolerant", "EMARMOUR™ series", "CISPR25 Class 5", and the like.

AEC-Q100 is one type of automotive noise emission standard, established for customers by the Automotive Electronics Council (AEC); categories include the following.

  • AEC-Q100: Semiconductor integrated circuits (LSIs, ICs, etc.)
  • AEC-Q101: Discrete semiconductor components (transistors, diodes, etc.)
  • AEC-Q200: Discrete passive components (resistors, capacitors, inductors, etc.)

In AEC-Q100, ambient temperatures during operation are defined as grades 0 to 3. The low-temperature side is -40°C, and on the high-temperature side there are, in grade order, +150°C, +125°C, +105°C, and +85°C. In REV-G Appendix 5 of the same standard, SAE J1752/3 is cited, and radiated emission (RE) by a TEM cell or a wideband TEM cell is defined.

High EMI tolerance, and inclusion in the EMARMOUR™ series, mean that the device does not easily malfunction due to external electromagnetic compatibility (EMC) noise (that is, the semiconductor integrated circuit tends not to malfunction even in an environment with a large amount of electromagnetic noise).

Conformance to Class 5 of the CISPR25 standard means that, in the automotive noise emission standard (international IEC standard), conducted emission and radiated emission are below the limiting values (only small amounts of electromagnetic noise are generated by semiconductor integrated circuits). Class 5 limiting values are the strictest.

As a slight digression, in the international IEC standards and international ISO standards, methods of measurement relating to electromagnetic compatibility (EMC) are standardized. You should be aware though that numerical values appearing in the documents are not standard values, but are limiting values (reference values). In actuality, each of the automotive OEM manufacturers in Europe has its own separate standards, and where measurement methods are concerned, they cite the IEC or ISO standards, but they stipulate their own unique standard values where component delivery is concerned.

Thank you for your kind attention.

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