Atec Sorensen-SL Series - Manual (Page 2)

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Electronic Load Selection
Often the selection of programmable power
supplies is based upon volts and amps capability.
However when selecting an electronic load,
it is important to account for volts, amps and
power. The power limit is displayed on a constant
power curve. A load must be selected so that
the operating points are within the Power Curve
(see Figure 1). For many applications in which
different power sources are tested, there may be
high voltage, low current requirements as well
as low voltage, high current requirements. A
single load may be able to handle both with good
programming resolution. In cases where a single
load may not work, the broad range of current,
power and voltage available in the SL series
allows optimum selection depending upon the
voltage, current, power required.
Applications
Low Voltage Operation
All SL series loads operate well below 1V.
However in many applications, such as fuel cell
research and microprocessor voltage regulator
modules (VRM), the voltage at the load inputs
can be 0.1 to 0.2V. This low voltage does not
allow the load transistors to fully turn-on (bottom
right corner of the power contour). To utilize the
full rated current of an electronic load, a boost
supply can be placed in series to increase the
voltage. While a fixed voltage DC-DC converter
can be used as the boost supply, a programmable
power supply is preferred to keep the load
voltage at the minimum to draw full current as
the device under test ramps up in voltage.
V
olts
Current
Figure 1 - Power Curve
Device Under Test
(Low Voltage DC
Power Supply)
SL Series
SLM-4: Chassis SLD: Dual
Input DC
Module SLM: DC
Module SLD: Dual
Input DC
Module SLM: AC
Module
SLH: DC Electronic Load SLH: AC Electronic Load SLM-1 Chassis
260