Page 13 - EngineerIT July 2022

ELECTRONICS

functions as the main switching circuitry automatically controls the corresponding test and measurement equipment such as the
of a buck (step-down) converter in DC supply, electronic load, and multiplexed data acquisition device (DAQ) to measure
conjunction with the LTC3861 dual, temperature, current and voltage figures directly from the demo board, and then plot
multiphase step-down voltage mode those measurements on the GUI. Important telemetry data from on-board devices are also
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DC-to-DC controller with accurate current gathered by the software through PMBus/I C protocol. All this information is important in
sharing. comparing system efficiency and power losses.

DrMOS analysis evaluation Data and results
hardware The following test results cover the steady-state performance measurements, functional
The analysis demonstration hardware has performance waveforms, thermal measurement and output noise measurement. The
the following key features: demonstration board was tested with the following configurations:
• A PWM controller that can operate • Input voltage: 12 V
on a wide range of input and output • Output voltage: 1 V
voltages and switching frequencies. • Output load: 0 A to 60 A
In this application, the controller is • Switching frequency: 500 kHz and 1 MHz
LTC7883, a quad output polyphase
step-down DC-to-DC voltage-mode
controller, shown in Figure 2.
• Identical power stage design for both
the LTC7051 and competitor devices.
• LTpowerPlay® power system
management environment for
comprehensive telemetry of system
performance provided by the
LTC7883.
• Can withstand extended ambient
temperature in accordance with the
specified operating temperature
range of both ADI and competitor
devices.
• Board is designed for easy thermal
capture and measurement. Figure 2. Analysis demonstration board block diagram.

The DrMOS analysis demonstration
board is shown in Figure 3. The board
was carefully designed to include the
key features previously mentioned.
Components are symmetrically and
systematically placed across each power
rail and have the same PCB size and area
to limit discrepancies between the power
rails. Layout routing and layer stack-up
are done symmetrically as well.

DrMOS analysis testing Figure 3. DrMOS evaluation board, top and bottom. PCB dimensions: 203 mm × 152 mm × 1.67
mm (L × H × W) with 2 ounces of copper thickness.
methodology and software
Aside from the demonstration board
itself, test setup and testing methodology
are equally important for unbiased
data and results. For this purpose, the
team also created a complementary
evaluation software with a graphical user
interface (GUI) shown in Figure 4 for a
more user-friendly approach of testing
and data gathering. The user just needs
to specify input and output parameters
and the software will take care of
the automated testing. The software Figure 4. DrMOS evaluation software, showing the configuration and thermal analysis tab.

EngineerIT | July 2022 | 11