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dc2518af
DEMO MANUAL DC2518A
Energy Metering
The LTC2975 is capable of high-side current sensing of
the input power supply. This feature allows the manager
to measure input supply current. Select the READ_IIN
register to display the telemetry plot. The input current
reading will be ~130mA if all channels are enabled and
V
IN
= 12V. Notice the current reading move lower as you
turn channels off.
ADVANCED DEMO BOARD OPERATIONS
The manager also measures input supply voltage and is
therefore able to report input power as well. Since energy
is the product of power and time, accumulated energy is
provided based on the manager’s internal time base.
The meter displayed in the upper right hand corner of the
GUI provides a number of bits of information. The needle
is a real-time indicator of input power and the smaller
five dials show the total accumulated energy similar to a
home electricity meter. Digital readouts are also provided
for convenience.
The DC2518A demo board has two power supplies that are
capable of relatively high voltages, ±48V. Be careful when
handling the board with these channels enabled since the
voltage difference between the two is 96V.
The LTC2975 is able to monitor and measure four outputs
and its input power supply. LTpowerPlay offers a simple
and easy to understand interface that brings together input
and output current, voltage, power, and energy readings.
You may also view the input current, input voltage, input
power, and input energy together in tabular format. These
appear in the telemetry portion of the GUI. The MFR_EIN
register holds the accumulated energy value in milli Joules.
There is also a total time that the energy accumulator has
been active and is shown as the MFR_EIN_TIME register.
The GUI will automatically update the displayed SI prefix
as the units change from mJ to J to kJ.
To demonstrate the meter readings and register values,
first select the MFR_EIN register to display the energy
in the telemetry plot. Turn off all channels by setting the
RUN switch to the off position. You will notice that the
slope has changed. The accumulated energy rate is the
