AMC1203_15 Datasheet, PDF (18/29 Pages) Texas Instruments – 1-Bit, 10MHz, 2nd-Order, Isolated Delta-Sigma Modulator

AMC1203
SBAS427C – FEBRUARY 2008 – REVISED JUNE 2011
ISOLATION GLOSSARY
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Creepage Distance: The shortest path between two
conductive input to output leads measured along the
surface of the insulation. The shortest distance path
is found around the end of the package body.
the leakage current produces an overvoltage at the
site of the discontinuity, and an electric spark is
generated. These sparks often cause carbonization
on insulation material and lead to a carbon track
between points of different potential. This process is
known as tracking.
Clearance: The shortest distance between two
conductive input to output leads measured through air
(line of sight).
Insulation:
Operational insulation—Insulation needed for the
correct operation of the equipment.
Basic insulation—Insulation to provide basic
protection against electric shock.
Supplementary insulation—Independent insulation
applied in addition to basic insulation in order to
ensure protection against electric shock in the event
of a failure of the basic insulation.
Double insulation—Insulation comprising both basic
and supplementary insulation.
Reinforced insulation—A single insulation system that
provides a degree of protection against electric shock
equivalent to double insulation.
Input-to Output Barrier Capacitance: The total
capacitance between all input terminals connected
together, and all output terminals connected together.
Input-to Output Barrier Resistance: The total
resistance between all input terminals connected
together, and all output terminals connected together.
Primary Circuit: An internal circuit directly connected
to an external supply mains or other equivalent
source that supplies the primary circuit electric power.
Secondary Circuit: A circuit with no direct
connection to primary power that derives its power
from a separate isolated source.
Comparative Tracking Index (CTI): CTI is an index
used for electrical insulating materials. It is defined as
the numerical value of the voltage that causes failure
by tracking during standard testing. Tracking is the
process that produces a partially conducting path of
localized deterioration on or through the surface of an
insulating material as a result of the action of electric
discharges on or close to an insulation surface. The
higher CTI value of the insulating material, the
smaller the minimum creepage distance.
Generally, insulation breakdown occurs either
through the material, over its surface, or both.
Surface failure may arise from flashover or from the
progressive degradation of the insulation surface by
small localized sparks. Such sparks are the result of
the breaking of a surface film of conducting
contaminant on the insulation. The resulting break in
Pollution Degree:
Pollution Degree 1—No pollution, or only dry,
nonconductive pollution occurs. The pollution has no
influence on device performance.
Pollution Degree 2—Normally, only nonconductive
pollution occurs. However, a temporary conductivity
caused by condensation is to be expected.
Pollution Degree 3—Conductive pollution, or dry
nonconductive pollution that becomes conductive
because of condensation, occurs. Condensation is to
be expected.
Pollution Degree 4 – Continuous conductivity occurs
as a result of conductive dust, rain, or other wet
conditions.
Installation Category:
Overvoltage Category—This section is directed at
insulation coordination by identifying the transient
overvoltages that may occur, and by assigning four
different levels as indicated in IEC 60664.
I: Signal Level: Special equipment or parts of
equipment.
II: Local Level: Portable equipment, etc.
III: Distribution Level: Fixed installation.
IV: Primary Supply Level: Overhead lines, cable
systems.
Each category should be subject to smaller transients
than the previous category.
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