1995 Mar 27 41
Philips Semiconductors
General Rating systems
RATING SYSTEMS
The rating systems described are those recommended by
the IEC in its publication number 134.
Deļ¬nitions of terms used
ELECTRONIC DEVICE
An electronic tube or valve, transistor or other
semiconductor device. This definition excludes inductors,
capacitors, resistors and similar components.
CHARACTERISTIC
A characteristic is an inherent and measurable property of
a device. Such a property may be electrical, mechanical,
thermal, hydraulic, electro-magnetic or nuclear, and can
be expressed as a value for stated or recognized
conditions. A characteristic may also be a set of related
values, usually shown in graphical form.
BOGEY ELECTRONIC DEVICE
An electronic device whose characteristics have the
published nominal values for the type. A bogey electronic
device for any particular application can be obtained by
considering only those characteristics that are directly
related to the application.
RATING
A value that establishes either a limiting capability or a
limiting condition for an electronic device. It is determined
for specified values of environment and operation, and
may be stated in any suitable terms. Limiting conditions
may be either maxima or minima.
RATING SYSTEM
The set of principles upon which ratings are established
and which determine their interpretation. The rating
system indicates the division of responsibility between the
device manufacturer and the circuit designer, with the
object of ensuring that the working conditions do not
exceed the ratings.
Absolute maximum rating system
Absolute maximum ratings are limiting values of operating
and environmental conditions applicable to any electronic
deviceofaspecifiedtype,asdefinedbyitspublisheddata,
which should not be exceeded under the worst probable
conditions.
These values are chosen by the device manufacturer to
provide acceptable serviceability of the device, taking no
responsibility for equipment variations, environmental
variations, and the effects of changes in operating
conditions due to variations in the characteristics of the
device under consideration and of all other electronic
devices in the equipment.
The equipment manufacturer should design so that,
initially and throughout the life of the device, no absolute
maximum value for the intended service is exceeded with
any device, under the worst probable operating conditions
with respect to supply voltage variation, equipment
component variation, equipment control adjustment, load
variations, signal variation, environmental conditions, and
variations in characteristics of the device under
consideration and of all other electronic devices in the
equipment.
Design maximum rating system
Design maximum ratings are limiting values of operating
and environmental conditions applicable to a bogey
electronic device of a specified type as defined by its
published data, and should not be exceeded under the
worst probable conditions.
These values are chosen by the device manufacturer to
provide acceptable serviceability of the device, taking
responsibility for the effects of changes in operating
conditions due to variations in the characteristics of the
electronic device under consideration.
The equipment manufacturer should design so that,
initially and throughout the life of the device, no design
maximum value for the intended service is exceeded with
a bogey electronic device, under the worst probable
operating conditions with respect to supply voltage
variation, equipment component variation, variation in
characteristics of all other devices in the equipment,
equipment control adjustment, load variation, signal
variation and environmental conditions.
1995 Mar 27 42
Philips Semiconductors
General Rating systems
Design centre rating system
Design centre ratings are limiting values of operating and
environmental conditions applicable to a bogey electronic
device of a specified type as defined by its published data,
and should not be exceeded under normal conditions.
These values are chosen by the device manufacturer to
provide acceptable serviceability of the device in average
applications, taking responsibility for normal changes in
operating conditions due to rated supply voltage variation,
equipment component variation, equipment control
adjustment, load variation, signal variation, environmental
conditions, and variations in the characteristics of all
electronic devices.
The equipment manufacturer should design so that,
initially, no design centre value for the intended service is
exceeded with a bogey electronic device in equipment
operating at the stated normal supply voltage.
