Product specifications

137
Power Products Power Products Terms (Continued)
Applications Information
More detailed specifications at www.agilent.com/find/power
Constant-voltage/current limiting
(CV/CL) power supply: a power supply
similar to a constant-voltage/con-
stant-current supply except that at
comparatively small values of load
resistance, its output current is
limited instead of being stabilized.
Crest factor: the ratio of the zero-to-
peak value to the rms value of a
waveform. This term is oft en used
to specify the maximum peak
amplitude that an AC power supply
can source (relative to its maximum
rms rating) without distortion.
Crowbar: see overvoltage protection.
Current limiting: the action, under
overload or short-circuit conditions,
of limiting the output current of a
constant-voltage supply to some
predetermined maximum value
(fixed or adjustable) and automati-
cally restoring the output voltage to
its normal value when the overload
or short circuit is removed. There
are three types of current limiting:
•
by constant-voltage/constant-
current crossover
•
by decreasing the output voltage
as the current increases
•
by decreasing both voltage and
current as the load resistance
decreases.
DFI: a TTL compatible output signal
that can be used as an alarm and
automatically initiates an action for
multiple power supply or electronic
load shutdown. The DFI signal is
commonly connected to RI of the
next supply. (See RI)
Downprogramming: the ability of a
power supply to discharge its output
capacitors independently of load.
The use of an active down program-
ming device can reduce t he fall time
of the output voltage.
Drift: the maximum change of
a power supply output or load
input voltage or current during an
8-hour period following a 30-minute
warmup, with all influence and
control quantities maintained
constant during the warm-up time
and the period of drift measurement.
Drift includes both periodic and
random deviations over the band-
width from zero frequency (DC) to
a specified upper frequency limit.
Efficiency: expressed in percent,
efficiency is the total output power
of the supply divided by the active
input power. Unless otherwise
specified, Agilent measures
efficiency at maximum rated
output power and at worst case
conditions of the AC line voltage.
Electromagnetic interference (EMI):
any type of electromagnetic energy
that could degrade the perfomance
of electrical equipment. The EMI
generated by a power supply can
be propagated either by conduction
(via the input and output leads)
or bt radiation from the units’
case. The terms “noise” and “radio-
frequency interference” (RFI) are
sometimes used in the same context.
Electronic load: an active device
which absorbs power. Loads are
used for the testing of the power
producing products.
Foldback: immediate shutdown of
the power supply output when a
crossover between constant voltage
and constant current mode occurs.
Both the voltage and current levels
are reduced (folded back).
Harmonics: the occurrence of this
type of distortion is based upon
the mathematical principle that all
periodic waveforms are made up of
a series of sine waves. As a result,
harmonic distortion is produced
at frequencies that are integer
multiples of the fundamental or
desired signal frequency. When
viewed in the frequency domain,
harmonics have an amplitude (often
expressed in db), frequency, and
phase characteristic relative t o the
fundamental.
Isolation: the maximum voltage
(including output voltage) either
output terminal may be floated
from earth ground.
Load cross regulation: the affect on
one output of a multiple output
power supply when another output
is programmed from zero to full
rated current.