Vicor VI-J00 Family DC-DC Converters and Configurable Power Supplies - Manual (Page 92)

Design Guide & Applications Manual
For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies
VI-200 and VI-J00 Family Design Guide Rev 3.5 vicorpower.com
Page 91 of 98
Apps. Eng. 800 927.9474 800 735.6200
Converter. An electrical circuit that accepts a DC input
and generates a DC output of a different voltage usually
achieved by high frequency switching action employing
inductive and capacitive filter elements.
Crest Factor. In an AC circuit, the mathematical ratio of
the peak to rms values of a waveform. Crest factor is
sometimes used for describing the current stress in AC
mains supply wires, since for a given amount of power
transferred, the rms value, and hence the losses, become
greater with increasing peak values. Crest factor gives
essentially the same information as power factor, and is
being replaced by power factor in power supply technology.
Cross Regulation. The effect of a load change on one
output to the regulation of another output. It usually only
applies to non postregulated (quasi) outputs.
Crowbar. An overvoltage protection method that shorts
the power supply output to ground in order to protect the
load when an overvoltage fault is detected.
CSA. Canadian Standards Association. Defines the
standards and safety requirements for power components.
Current Limiting. An overload protection circuit that
limits the maximum output current of a power supply in
order to protect the load and / or the power supply.
Current Mode. A control method for switch-mode
converters where the converter adjusts its regulating
pulsewidth in response to measured output current and
output voltage, using a dual loop control circuit.
Current Monitor. An analog power supply signal that is
linearly proportional to output current flow.
D
DC-OK Signal. Signal used to monitor the status of the
DC output.
Derating. A reduction in an operating specification to
improve reliability. For power supplies it is usually a
specified reduction in output power to facilitate operation
at higher temperatures.
Design Life. The expected lifetime of a power supply
during which it will operate to its published specifications.
Differential-Mode Noise. Noise that is measured
between two lines with respect to a common reference
point excluding common-mode noise. The resultant
measurement is the difference of the noise components of
the two lines. The noise between the DC output and DC
return is usually measured in power supplies.
Distributed Power Architecture (DPA). A power
distribution architecture that replaces multiple central
power sources with a single bulk supply that is converted
to the end-use voltages by DC-DC converters located at
the point of need. The growth of this design technique is
demonstrated by the size of the DC-DC converter market.
Distributed power can reduce the system size, reduce the
system weight, provide better operation with battery
power, and deliver more efficient sub-system isolation and
redundancy.
Drift. The change in an output voltage, after a warm-up
period, as a function of time when all other variables such
as line, load, and operating temperature are held constant.
Driver Module. The controlling module in a standalone
or Driver / Booster configuration. The Driver module
contains all the control circuitry.
Dropout. The lower limit of the AC input voltage where
the power supply just begins to experience insufficient
input to maintain regulation. The dropout voltage for
linears is largely line dependent, whereas for most
switchers it is largely load dependent, and to a smaller
degree line dependent.
Dynamic Load Regulation. The delta in output voltage
when the output load is rapidly changed.
E
Efficiency. The ratio of total output power to input power
expressed as a percentage.
Electronic Load. An electronic device designed to provide
a load to the outputs of a power supply, usually capable
of dynamic loading, and frequently programmable or
computer controlled.
EMC. Electromagnetic Compatibility. Relating to
compliance with electromagnetic emissions and
susceptibility standards.
EMI. Electromagnetic Interference. The generation of
unwanted noise during the operation of a power supply
or other electrical or electronic equipment.
ESR. Equivalent Series Resistance. The value of resistance
in series with an ideal capacitor that duplicates the
performance characteristics of a real capacitor.
26. Glossary of Technical Terms