Vicor VI-J00 Family DC-DC Converters and Configurable Power Supplies - Manual (Page 94)

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 93 of 98
Apps. Eng. 800 927.9474 800 735.6200
Impedance. The ratio of voltage to current at a specified
frequency.
Induced Noise. Noise generated in a circuit by varying a
magnetic field produced by another circuit.
Input Line Filter. An internally or externally mounted
lowpass or band-reject filter at the power supply input
that reduces the noise fed into the power supply.
Inrush Current. The peak current flowing into a power
supply the instant AC power is applied. This peak may be
much higher than the steady state input current due to
the charging of the input filter capacitors.
Inrush Current Limiting. A circuit that limits the amount
of inrush current when a power supply is turned on.
Isolation. Two circuits that are completely electrically
separated with respect to DC potentials, and almost
always AC potentials. In power supplies, it is defined
as the electrical separation of the input and output via
the transformer.
Isolation Voltage. The maximum AC or DC test voltage
that may be applied from input to output and / or chassis
of a power supply. Usually this has a time limit per
preregulatory agency such as EN60950.
Intermediate Bus Architecture (IBA). A power
distribution architecture that relies on non-isolated point-
of-load regulators (niPOLs), reducing the POL function to
regulation and transformation. The niPOLs operate from
an intermediate bus voltage provided by upstream isolated
converters. However, IBA has inherent limitations that
require tradeoffs between distribution and conversion loss
that limit responsiveness to rapid load changes. IBA has
proven effective as an interim method of containing
power system cost while addressing the trend toward a
proliferation of lower load voltages.
L
Leakage Current. A term relating to current flowing
between the AC supply wires and earth ground. The term
does not necessarily denote a fault condition. In power
supplies, leakage current usually refers to the 60 Hz
current that flows through the EMC filter capacitors
connected between the AC lines and ground (Y caps).
Linear Regulator. A regulating technique where a
dissipative active device such as a transistor is placed
in series with a power supply output to regulate the
output voltage.
Line Regulation. The change in output voltage when
the AC input voltage is changed from minimum to
maximum specified.
Line Voltage (Mains). The sine wave voltage provided to
the power supply, usually expressed in volts rms.
Load Regulation. The change in output voltage when
the load on the output is changed.
Local Sensing. Using the voltage output terminals of the
power supply as sense points for voltage regulation.
Long Term Stability. Power supply output voltage
change due to time with all other factors held constant.
This is expressed in percent and is a function of
component aging.
Low Line. The minimum steady state voltage that can be
applied between the +IN and –IN pins of a converter and
still maintain output regulation.
M
Mains. The utility AC power distribution wires.
Margining. Adjusting a power supply output voltage
up or down from its nominal setting in order to verify
system performance margin with respect to supply
voltage. This is usually done electrically by a system-
generated control signal.
MegaMod. A chassis mount packaging option that
incorporates one, two or three VI- / MI-200 Family
converters for single, dual or triple outputs having a
combined power of up to 600 W.
M-Grade. An industry standard where the operating
temperature of a device does not drop below –55°C.
MIL-SPECS. Military standards that a device must meet to
be used in military environments.
MiniMod. A junior size (VI- / MI-J00) version of the
VI- / MI-200 Family of DC-DC converters offering up
to half the power in a 2.28" x 2.4" x 0.5" (57,9 x 61,0 x
12,7 mm) package.
Minimum Load. The minimum load current / power
that must be drawn from the power supply in order for
the supply to meet its performance specifications. Less
frequently, a minimum load is required to prevent the
power supply from failing.
Module Evaluation Board. A test fixture used to
evaluate Vicor DC-DC converters.
MTBF (Mean Time Between Failure). MTBF is the point
at which 63% of a given population no longer meet
specification. It can either be calculated or demonstrated.
The usual calculation is per MIL-STD-217 Rev. E. Demonstrated
reliability is usually determined by temperature accelerated
life testing and is usually greater than calculated MTBF.
26. Glossary of Technical Terms