Generate Diode Curves with Excel and a Bench Power Supply
Published: 25th January 2022
When you need to quickly determine the forward voltage of a power diode, use your bench power supply. A bench power supply with an accurate measurement system, such as the Keysight EDU36311A Smart Bench Essentials DC power supply, shown in Figure 1, can apply a known voltage and precisely measure its ensuing output current.
Figure 1. EDU36311A Smart Bench Essentials power supply
To test a power diode, start with a low voltage and measure the current. Then increase the voltage and measure the resulting current. After several measurements, graph the results in Excel, as shown in Figure 2.
Figure 2. Diode voltage versus current curve
AUTOMATE THE TASK
Excel’s VBA programming, along with Keysight’s free Connection Expert, automates this task. The Connection Expert identifies the instrument’s address and passes SCPI commands through its library to the power supply. The EDU36311A offers USB and Ethernet for simple PC connectivity. With the interface cable in place, the Connection Expert software will find the power supply and its address.
A spreadsheet including a sample program is attached to this blog.
Open the spreadsheet:
Update the instrument address, the number of steps, and current limit, highlighted in the red box in Figure 3.
Edit the test voltages in column A.
The controls in the orange box call the VBA subroutines, starting with opening the instrument connection, running the measurement block routine, and finally closing the instrument connection.
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PathWave BenchVue software gives you the capability to easily control your instruments and perform in-depth analysis on your measurements. Besides that, the PathWave BenchVue software apps supports more than 700 Keysight Instruments and are continually expanding.