Browsing by Author "Tsai, Tsung-Hsun"

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99% High Accuracy Knee Voltage Detection for Primary-side Control in Flyback Converter
(2015)
Tsai, Tsung-Hsun
;
Chen, Ke-Horng
;
Tsai, Tsung-Yen
;
Lin, Jian-Ru
;
Lin, Ying-Hsi
this paper proposed the adaptive knee voltage detection (KVD) technique to improve the output voltage accuracy of the primary side regulator. Owing to the insertion of the snubber circuit for reducing overshoot voltage, conventional KVD technique fails to get the output voltage information and thus to deteriorate the output voltage accuracy. Analysis of the snubber circuit and the resonance of the primary side can determine the band-pass filter in the proposed AKVD technique to get high accuracy output information without being affected by any kinds of resonances. Test chip designed in VIS 0.5 mu m BCD process demonstrates the accuracy of the output voltage higher than 99%. Besides, any abnormal detection won\'t happen and thus the output ripple can be kept low.
High Accuracy Knee Voltage Detection for Primary-Side Control in Flyback Battery Charger
(2017-04-01)
Yang, Shang-Hsien
;
Tsai, Tsung-Hsun
;
Chen, Hsin
;
Chiu, Chao-Chang
;
Chen, Ke-Horng
In a primary-side control flyback charger, the accuracy of a conventional knee voltage detection (KVD) approach to obtain the output voltage is influenced by the inclusion of a snubber circuit. Although the snubber circuit dampens the ringing voltages due to switching, it also affect the resonance frequency which would reduce the timing of the sampling circuit, resulting in the inaccurate sampling of output voltage. By analyzing the snubber circuit and its resonance on the primary side, this paper implements a proposed accuracy knee voltage detection (AKVD) technique to compensate for the induced resonance frequency. Furthermore, the proposed constant current (CC) regulator ensures the accuracy of CC mode by compensating the sensing current error caused by the switching delay of the power transistor. A prototype consisting of a test chip fabricated with a 0.5 mu m BCD process demonstrates a voltage accuracy exceeding 99.63%. This is achieved by mitigating abnormal detections and thus ensuring correct control of charging current throughout the charging period.