What is it?

The Design Verification Module (DVM) is an add-on to SIMetrix / SIMPLIS that provides the user with a powerful automated test suite for switching power supplies. Before DVM, configuring a typical SIMPLIS application circuit for analysis required the user to:

• Configure analysis parameters (.AC, .TRAN, .POP statements)
• Appropriately set input sources and output loads
• Activate special purpose probes and components (Bode Plot probes, AC sources, etc...)

While not particularly complicated, making these changes is time consuming and requires a certain amount of tweaking and customization. Often, the end result is several copies of the application circuit, each setup for a difference type of analysis. With the Design Verification Module, only one copy of the application circuit is required, and the setup for each test is automated.

Choosing a Circuit

To work with DVM, a schematic should be able to successfully execute an AC analysis using the SIMPLIS simulation engine. Below is an example schematic using the LTC3406B in a synchronous rectified buck application circuit.

Configuring a Circuit

To configure a circuit for DVM, perform the following steps:

1. Using the simulation configuration dialog (Simulator > Choose Analysis...), configure your circuit to run an AC analysis.
   
   
2. Replace the input voltage source with the DVM Input Source (DVM > SyncBuck DVM > Place > Input Source).
   
   
3. Replace the output current source and/or load resistor with the DVM Output Load (DVM > SyncBuck DVM > Place > Output Load). The SENSE pin of the DVM Output Load symbol should be connected to the node in your output voltage sensing circuit where you would normally sense the positive output voltage.
   
   

   
   If you've included a Bode Plot probe in your schematic, you should either remove it or disable the AC source that accompanies it.
   

   
4. Place the DVM Control somewhere on your schematic (DVM > SyncBuck DVM > Place > DVM Control).
   
   
5. Double click the DVM Control symbol and enter appropriate values for your circuit under the General, Input and Output tabs. Advanced and Analysis options can be set later.
   
   

Auditing a Circuit

To audit the circuit, choose the following menu option: DVM > SyncBuck DVM > Audit Circuit. If it passes, you should be ready to run DVM tests. The audit checks for the following:

• Presence of a DVM Input Source Symbol
• Presence of a DVM Output Load Symbol
• Presence of a DVM Control Symbol
• Presence of required properties in the DVM Control Symbol

The audit cannot, unfortunately, check to make sure that values entered into the DVM Control are correct for your circuit, so be thorough and careful when filling out the dialog. Also, variables and expressions are not supported as values for the DVM Control.

Running Tests / Test Suites

Tests can be run either individually or in groups from the DVM menu.

To run just one test, select it from the DVM menu.

To run a group of related tests, navigate to that group in the DVM menu, then choose "Run All".

To run the entire test suite, choose "Run Test Suite" from the DVM menu.

Progress of an individual simulation is displayed through the standard SIMPLIS status window. Progress of the current batch of tests being run is displayed in the SIMetrix / SIMPLIS Command Shell window.

Reporting Results

When the execution of a test or test suite is complete, the Design Verification Module creates an HTML report for each test, as well as a report that provides an overview of the execution of the test suite.

The overview report contains general information about the test suite (name of the schematic, the date and time the test suite was launched, the number and status of tests run, and the total time) as well as links to the individual test reports.

An individual test report contains the following:

• Test Details: The name of the schematic, the date and time the test was run, the status of the test, links to the simulator input and output files.
• Measured Scalar Values: Automatically calculated metrics for simulation waveforms (min, max, avg, rms) as well as test specific metrics (gain and phase margin, recovery time, switching frequency, etc...)
• Measured Spec Values: Comparing the automatically calculated metrics with the circuit specifications as defined in the DVM Control Symbol results in either a PASS or FAIL. The combined results of all the measured spec values determines the overall status of the test.
• Waveform Images: Featured waveforms are converted to static images, grouped and displayed inline in the report. A link is provided to the .sxgph file containing the actual waveform data for further analysis.
• Other SXGPH File Links: All waveform output from the simulation is saved in .sxgph files. Any non featured waveform grouping data can be viewed in the SIMetrix waveform viewer.