| Summary: | 碩士 === 國立交通大學 === 電機工程學系 === 107 === As aerospace industry and electric vehicles use more and more power electronic devices, the reliability and the safety of power electronic systems become more and more important in the future. In power management IC, the power MOSFETs are the most representative devices affected by aging effects. Traditionally, it is determined by the measurement of the threshold voltage and on-resistance. However, it has to interrupt the function of power electronic systems and be done off-line. Due to the inconvenient and complicated maintenance, this thesis focuses on-chip and on-line measurement methodology. This thesis presents a method to measure the threshold voltage of power MOSFETs in current-mode controlling buck converter. We design a built-in self-measurement module to measure the threshold voltage of the power MOSFETs online. The built-in current sensor has the similar working condition and environment as the p-type power MOSFETs do. When the state of the p-type power MOSFET is in off duty of the PWM cycle, we utilize a successive approximation register to approximate the threshold voltage of the current sensor. The output digital code of the SAR represents the threshold voltage of the sensor transistor as well as the state of the health of the entire power MOSFETs. If the condition is serious, an alarm will be issued to avoid catastrophic error.
The design is designed in TSMC 0.25 1P5M HV CMOS process. The frequency of system clock is 1MHz. The maximum efficiency of the converter is 90.46%. At the different corner, the measured threshold voltages are 1.6mV~10mV different from the listed in the technology file.
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