| With the development of China's economics, people's standard of living has been greatly improved, The amount of household appliances and industrial appliances increases rapidly, people have been inseparable from a wide variety of electrical appliances in their daily life, thus caring more and more about safety and stability of electricity. And now, the residual current circuit breaker which can protect people's life is widely used. However, most of the residual current circuit breakers now used in the China's market are not designed under China's National Standard, these imported chips are not suitable for China's electrical transmission line and always show a high rate of nuisance tripping which seriously impacts the installation rate of residual current protector. Nevertheless, there is no improved chip now in China to substitute the imported one. And such situation necessitates a good performance chip under Chinese electrical condition.Both international and Chinese standards about residual current protector have been intensively studied in this paper. The reason why imported chip is not suitable for China's electrical transmission line is theoretically explained through detailed comparison and analysis of the key index parameters between international standard and China's national standard, and this paper also present a novel anti-interference method by employing 10ms non-actuating time during direct contact protection in accordance with China's national standard. Such effective method has been implemented in our chips successfully.The HH series residual current protector ASIC including HH-1 household leakage protector and HH-2 general-level leakage protector have been designed in this paper. Co-use of the two chips can supply user-middle-main step protection. The main advantages of such chips are shown below:1. Strong anti-interference ability. The regularity of electrical disturbance signal has been concluded through observation and analysis of such interference. Several novel anti-interference methods has been employed, such as introduction of 10ms non-actuating time, filtering of peak pulse, detection of signal continuity and adopting constant delay.2. High precision delay. By using high precise fine adjustable internal oscillator, we can get high precise oscillation frequency. We can also effectively improve the delay accuracy through the utilization of digital module, thus, matching among several application levels becomes more convenient.3. Programmable application. HH-1 chip can switch between normal direct contact and indirect S type through programming; HH-2 chip can also achieve different threshold voltage range by programming. Such programmable technology has greatly improved the chip's scope of application as well as flexibility.4. Multifunction and low power. Over voltage protection is integrated in HH-1 chip and reclosing function is implemented in HH-2 which can enrich its application. The power dissipation of HH-1 is only 1.75mW and that of HH-2 is 2mW, which is only ten percent of m54123's power comsumption.HH series chips joined the MPW (multi-project wafer) plan laughed by Shanghai Integrated Circuit Center and were implemented in WuXi Shanghua 0.6um mix-signal process. The chips are tested after fabrication and encapsulation, and the test result is excellent which indicates all the parameters of the chip meet the specifications. The chips pass the third-party certification including Electromagnetic Compability (EMC) test, and acquire qualified user's report. |
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