MOSFETs and IGBTs are the most critical yet most prone-to-failure components in switching power supplies! The primary cause is typically overvoltage or overcurrent leading to a significant increase in power dissipation, resulting in device damage or even potential explosions. SOA (Safe Operating Area) testing serves as a crucial evaluation to ensure their safe operation!

SOA Security Work Area

SOA refers to the Safe Operating Area, which is a two-dimensional graph composed of a series of constraints on drain-source voltage (VDS) and drain current (ID). When a switching device operates normally, neither its voltage nor current should exceed this defined range—this region constitutes the device's Safe Operating Area. The SOA Safe Operating Area is a crucial guarantee for ensuring the stable operation of switching power supplies without issues such as damage or explosions, making it one of the essential testing items in the current switching power supply industry.

Figure 1 SOA Safe Operating Area

Traditional SOA testing methods essentially determine whether voltage, current, and power meet the specified zone conditions. Conventional approaches require differential probes and current probes to separately measure voltage and current data, which is then saved and imported into a computer for secondary analysis to plot data points and verify compliance with the zone requirements.

However, traditional oscilloscopes have limited storage depth and short testing durations, while SOA testing requires repeated measurements to assess the long-term stability of MOSFETs. This process consumes significant human resources. Additionally, as products are used in varying environments, multiple tests under different conditions are necessary, leading to unpredictable labor costs.

ZDS Oscilloscope Solution

To address the long-standing challenge of SOA Safe Operating Area testing for engineers, ZDS3024 and higher models introduced an automated SOA testing plugin. Simply configure the relevant parameters, and it will automatically determine the safe operating zone, analyze whether voltage and current fall within the safe area, and conduct continuous testing. The results, including statistical conditions and pass/fail outcomes, are displayed in the bottom-right corner. Furthermore, after deeply understanding engineers' testing needs, ZLG engineers added multiple user-friendly features for diverse environments:

1. Supports continuous testing and tracks the total number of passes and failures, making it suitable for prolonged burn-in testing.

2. Supports touch (waveform exceeds safe zone) stop, automatic screenshot, and audio prompt operations;

3. The safe operating area (SOA) can be set through voltage, current, and power limitations, and can also be customized.

Figure 2 SOA Safe Operating Area Analysis Interface

More Power Customization Features

Beyond this, we've deeply immersed ourselves in the power supply industry by launching a suite of power analysis plugins! These include loop analysis, harmonics, inrush current, switching losses, SOA, and many other power analysis functions, already serving nearly a thousand domestic power supply enterprises! Moreover, in the future, we will continue to delve deeper into the power supply industry, uncovering more features that meet the needs of power supply engineers, and persistently provide high-quality solutions for professionals in this field.

Figure 3 ZDS Power Analysis Plugin