PSU Characterisation with Rigol Equipment using SCPI

Introduction 
This brief blog provides a hobbyist solution for characterising the performance of devices such as DC supply modules using measurements from SCPI-capable test equipment.

Set up for Power Supply Test Fixture

Datasheets and Measurements
In most cases, the datasheet for a piece of hardware, be it a component or a printed circuit assembly (PCA), will provide sufficient information. For other cases, the performance or characterisation of the hardware requires a specific test or behaviour to be verified or quantified.

DC Supply Module Test (Example)
In this blog, the power-up voltage of an off-the-shelf power supply module was logged for different temperatures. The Device Under Test (DUT) was the STS1024S05 from XP Power.

A small test fixture was created to test multiple XP Power modules. In this example blog, the schematic shows connections to the supply.

Schematic for Test Fixture

The test fixture used pogo pins to connect to the castellated power module pads and banana sockets to interface with the test equipment.

Assembled Test Fixture with Device Under Test (DUT)

Test Software
The project's test software was originally started with Lab Windows. However, with many PyVISA Python examples available, Python in VS Code was selected instead. A Python script from Core Electronics was almost identical to the script required test setup, so the script was modified for this example. All credits to the team at Core Electronics for the original Python script.

Changes were made to the original script to suit the test setup. In the updated script, the test equipment type, the voltage step size of 100 mV, and the reported and logged voltages were updated as published here.

Measurements
The temperature was verified with a PC210 thermal camera for the duration of the measurement. The temperature variation was around 5 °C, which was attributed to the heating and cooling equipment. 

A full listing of the measurements is available in a combined Excel file here. 

Plotted below are measurements for the voltage range between DC 5.0 V and 6.0 V, where the DUT output was activated. The plot indicates differences in the DUT turn-on voltage for the temperature range sampled.

Measurement Results with STS1024S05