Startup() Test Objective
The purpose of the Startup() test is to determine the converter response to a startup. The input is configured as a Ramped Input Source with the starting voltage set to 0V. The output is configured as a resistive output load. The final voltage as an argument to the Startup() function, DVM also disables all initial conditions on the schematic before starting the simulation. For information about how to change this behavior, see the PRESERVE_IC optional parameter.
A transient simulation is used in the Startup() test with the initial value of 0V. The timing for both the ramp input source and the transient simulation is determined by the values entered in the Startup page of the Full Power Assist DVM control symbol, which is shown below.
The test report includes source, load, and frequency graphs as well as the following scalar values which are defined in the Measured Scalar Values section below:
- Switching frequency
- Output voltage turn-on time
- Overshoot voltage
In this topic:
Testplan Syntax
The Startup() function has the following syntax with the arguments described in the table below:
Startup(REF, FINAL_VOLTAGE) Startup(REF, FINAL_VOLTAGE, OPTIONAL_PARAMETER_STRING)
| Argument | Range | Description |
| REF | n/a | The actual reference designator of the DVM Source or the generic syntax of INPUT:n where n is an integer indicating a position in the list of DVM sources. |
| FINAL_VOLTAGE | The final source voltage | |
| OPTIONAL_PARAMETER_STRING | n/a | Parameter string with a combination of one or
more timing parameters:
|
parameter_name1=parameter_value1 parameter_name2=parameter_value2The order of the parameter key-value pairs does not matter.
The PRESERVE_IC parameter is unique to the Startup() test objective. If this parameter value is equal to the string TRUE, DVM will not clear the initial conditions from the circuit under test before the simulation starts. This allows you to use a specific set of initial conditions for the design.
Simulation Timing
DVM sets the timing parameters for the Startup() test objective based on values that you enter on the following two tabs in the DVM Full Power Assist control symbol:
- Startup tab: Cycles Before Event, Cycles to Recover, and Slew Rate
- Circuit Specifications page: Switching Frequency
The time delay, rise time, and the simulation stop time are determined by these calculations:
\[ \text{TIME_DELAY} = \frac{\text{CYCLES_BEFORE_EVENT}}{\text{SWITCHING_FREQUENCY}} \]
\[ \text{RISE_TIME} = \frac{\text{FINAL_VOLTAGE}}{\text{SLEW_RATE}}\]
DVM then calculates the simulation stop time as follows:
\[ \text{STOP_TIME} = \text{TIME_DELAY} + \text{RISE_TIME} + \frac{\text{CYCLES_TO_RECOVER}}{\text{SWITCHING_FREQUENCY}}\]
The input voltage ramp/step timing is annotated on the graph below:
| Annotation | Value |
| X0 | TIME_DELAY |
| X1 | TIME_DELAY + RISE_TIME |
| Y0 | 0 |
| Y1 | FINAL_VOLTAGE |
Source and Load Subcircuit Configuration
The Startup() test objective sets the source and load subcircuits to the following:
| Source | Load |
| Ramp Input Source | Resistive Load |
Loads other than the output under test are set to the Resistive Load. All other sources are set to the DC Input Source.
Measured Scalar Values
The Startup() test objective measures the following scalar values,where {load_name} and {src_name} are replaced by the actual load name source name:
| Scalar Name | Description | ||||||||||
| sw_freq | A number which represents the converter switching frequency. This scalar is generated from a fixed probe with curve label DVM Frequency. For more information, see Measuring the Switching Frequency. | ||||||||||
| vout{n}_turn_on_time | The number
{n} in the scalar name is an integer indicating a
position in the list of DVM loads. The two possible return values are the following:
|
||||||||||
|
The Average, Minimum, Maximum, RMS and Peak-to-Peak values for each load voltage and current taken over the entire simulation time window. | ||||||||||
|
The Average, Minimum, Maximum, RMS and Peak-to-Peak values for each source voltage and current taken over the entire simulation time window. |
Measured Specification Values
In the following table, {load_name} is the name assigned to each load. The default value is LOAD. DVM forces each load name to be unique so that the scalar and specification values for each load are unique.
| Scalar Name | PASS/FAIL Criteria |
| Min_V{load_name} | The minimum value of the output voltage during the simulation time is greater that the minimum specification value. |
| Max_V{load_name} | The maximum value of the output during the simulation time is less than the maximum specification value. |
| Overshoot_V{load_name} | The maximum value of the output during the simulation time is less than the maximum overshoot specification value. |
Testplan Example
The Startup() test objective is used in several built-in testplans. Shown below is a startup test from the Syncbuck_1in_1out testplan. This test configures the source to ramp to the Maximum symbolic value. This Maximum symbolic value is defined on the DC Input page of the Full Power Assist DVM control symbol.
| *?@ Analysis | Objective | Source | Load | Label |
|---|---|---|---|---|
| Transient | Startup(INPUT:1, Maximum) | Load(OUTPUT:1, 50%) | Transient|Startup|50% Load|0V to Vin Maximum |
Optional Parameter String
The following Startup() test objective uses the OPTIONAL_PARAMETER_STRING argument to set the final voltage to the Maximum symbolic value, the time delay to 25us and the rise time to 100us.
Startup(INPUT:1, Maximum, TIME_DELAY=25u RISE_TIME=100u)
Test Report
You can view the complete test report in a new browser window here: Startup() Test Report. Below is an interactive link to the same test report.