GUI Register Page
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In Step 5, the user enters the desired PMBus slave address. Note that changing the PMBus slave address
in this step does not change the physical address, but shows how the address pins of the LM25066 need
to be configured to achieve a desired address. Once the ADR pin jumpers are configured for a particular
address, power to the LM25066 needs to be cycled and the GUI restarted in order for the new address to
take effect.
When invalid or incorrect inputs are given to the design tool, text associated with the faulty input will turn
red. Positioning the mouse cursor over the red text will give additional information about any design
conflict.
Component and parametric results are shown to the right as well as the LM25066 operational area chart.
The operational area chart shows the minimum, typical, and maximum SOA protection areas for a given
design. For a robust design, the SOA of the MOSFET used should be above the MAX protection SOA line
for all operating areas. To help make this determination, step 2 allows the user to select the SOA curves
for several popular MOSFETs or to input the SOA data for the desired MOSFET.
Once complete, the design should be saved by selecting the File menu, and then Save. Once the
hardware is modified to match the design, the GUI should be restarted and the hardware configuration file
loaded right after the LM25066 is detected and placed. If the values in the design tool are different than
the values on the board, erroneous telemetry and fault data will be reported by the GUI. To return to the
block view of the device, press the Home button located at the far left in the menu bar.
The design tool is also useful to calculate the PMBus coefficients. With the correct value for current sense
resistor (RS1), the tool will calculate the coefficients to scale the raw telemetry. The coefficients can be
viewed by selecting View from the main menu bar, and then selecting the PMBus Coefficient Editor. When
the PMBus Coefficient Editor is opened, press the Get All button to show the currently used coefficients.
If desired, the equations used in the design tool can be calculated by hand using the equations provided in
the datasheet. However, note that the design tool calculates parameters factoring in worst case
tolerances, while the equations in the datasheet are based on typical thresholds.
11 GUI Register Page
The GUI Register Page, as shown in Figure 10, provides the user with several features to help better
understand the functionality of the LM25066. These features include the ability to read telemetry, device
identification and status registers, as well as being able to monitor the SMBus Alert and PGOOD
interrupts, and to turn the output on and off with the OPERATION button.
10 AN-2100 LM25066 Evaluation Board SNVA464C–December 2010–Revised April 2013
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