by Tektronix Advanced Semiconductor Laboratory To more thoroughly assess the aging characteristics of power devices, high-temperature operating life (HTOL) tests have increasingly gained attention from power device test engineers. HTOL replicates the operational conditions of power devices by integrating them into actual power circuits. By subjecting devices to stress through continuous hard or soft switching circuits, HTOL delivers aging effects that closely mimic real-world usage, providing a more accurate evaluation of device performance under diverse stress conditions. For instance, in hard-switch aging, based on the topologies outlined in the JEP182 standard, the device under test can be incorporated into various circuit configurations, including hard switch, soft switch, or resistive load switch setups. This approach enables a more comprehensive simulation of the device’s operational state in real applications, facilitating a more effective assessment of its long-term reliability. Using figure (a) as an example, the circuit configuration resembles the double pulse test setup. A power resistor is incorporated into the upper tube loop to dissipate the inductor’s energy during the freewheeling phase stage to ensure the current balance during the continuous switching process. As the inductor L’s energy is dissipated through resistor R, significant heat is generated, necessitating a large heat sink for high-power testing. This increases the circuit’s size and restricts its total power capacity, preventing the chip from operating under high voltage and high current conditions. To enhance aging efficiency, intensify stress conditions during testing, and better replicate real-world scenarios, the test circuit can be optimized. By eliminating the resistive load and employing an inductive load, the circuit allows power devices to operate under hard switching conditions while minimizing energy loss as heat, thereby improving efficiency and reducing heat dissipation. We can adjust the switching sequence of the four power devices to enable Q1/Q4 to operate under continuous hard switching conditions while Q2/Q3 function in freewheeling mode, achieving a continuous hard switching circuit without a resistive load. Using GaNPower’s 650V GaN HEMT device as an example, we conduct HTOL testing with a controlled switching frequency of 100 kHz. During continuous switching, we employ an oscilloscope (Tektronix), a high-voltage power supply (EA 1500V DC power supply), and a clamp test probe (Hunan Lanhai Electric, stabilization time under 100 ns) to monitor the on-resistance trend of the power device during the turn-on phase, providing insights into the device’s aging process. Using GaNPower’s 650V GaN HEMT device as a case study, we conducted an HTOL test. The test measured the on-resistance variation of the power device during switching using a Tektronix oscilloscope, an EA 1500V high-voltage DC power supply, and a Hunan Lanhai Electric clamp probe. By optimizing the switching sequence of the power devices, we achieved a continuous hard switching circuit without a resistive load. Test results indicate that over a 61-hour period, the dynamic on-resistance of both GaN devices and CREE’s SiC MOSFET remained largely stable with no significant increase. When the test voltage was raised to 520V and extended to 245 hours, the dynamic on-resistance exhibited a gradual increase but stayed within acceptable limits. Through linear fitting, the device’s continuous operating lifetime under specific conditions can be estimated. The figure below displays the dynamic on-resistance waveform captured using a Tektronix MSO58B series oscilloscope. We calculate the dynamic on-resistance value at a specific point by dividing the on-voltage by the on-current. After extended testing, the relative drift in dynamic on-resistance becomes evident. During testing, continuous hard switching of the power device generates switching power losses, leading to device heating. T