Self-Calibrated Knee Voltage Detector With 99.65% High Accuracy for AC Charger System in 0.5 $\mu{\rm m}$ 500 V UHV Process

The self-calibrated knee voltage detector (SC-KVD) for electrical isolation primary side charger applications is proposed. The removal of the feedback network which is used in conventional designs and occupies at least 30 mm² can save PCB area up to around 11%. Besides, the SC-KVD can dynamically adjust the detection point to improve the accuracy to 99.65% compared to the prior arts. The test chip fabricated in 0.5 μm 500 V UHV process can be powered on directly by the AC source owing to the 500 V ultra-high voltage device. Hence, the battery charger can be made more compact and portable than it was and the battery life can be prolonged and guaranteed.