TX4939 Datasheet, PDF (46/756 Pages) Toshiba Semiconductor – 64-Bit TX System RISC

Handling Precautions
3.3 Design
To achieve the reliability required by an electronic device or system, it is important not only to use the
semiconductor device in accordance with specified absolute maximum ratings and operating ranges, but also to
consider the environment in which the equipment will be used, including factors such as the ambient temperature,
transient noise and current surges, as well as mounting conditions which affect semiconductor device reliability.
This section describes general design precautions. Be sure to refer to the individual ratings of each product at the
time of design.
3.3.1 Absolute Maximum Ratings
The absolute maximum ratings of a semiconductor device are a set of ratings that must not be
exceeded, even for a moment. Do not exceed any of these ratings.
Exceeding the rating(s) may cause device breakdown, damage or deterioration, and may
result injury by explosion or combustion.
If the voltage or current on any pin exceeds the absolute maximum rating, the overvoltage or overcurrent causes
the device’s internal circuitry to deteriorate. In extreme cases, heat generated in
internal circuitry can fuse wiring or cause the semiconductor chip to break down.
If the storage or operating temperature exceeds the absolute maximum rating, the
device internal circuitry may deteriorate and the bonded areas may open or the
package airtightness may deteriorate due to the differences between the thermal
expansion coefficients of the materials from which the device is constructed.
Although absolute maximum ratings differ from product to product, they essentially concern the voltage and
current at each pin, the allowable power dissipation, the connecting area temperatures, and storage temperatures.
Note that the term “maximum rating” which appears in semiconductor technical datasheets and
the like refers to “absolute maximum rating.”
3.3.2 Operating Range
The operating range is the range of conditions necessary for the device to operate as specified in individual
technical datasheets and databooks. Care must be exercised in the design of the equipment. If a device is used
under conditions that do not exceed absolute maximum ratings but exceed the operating range, the specifications
related to device operation and electrical characteristics may not be met, resulting in a decrease in reliability.
If greater reliability is required, derate the device’s operating ranges for voltage, current, power and temperature
before use.
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