A Primary Side Controlled AC-DC Controller With Constant Current Or Constant Voltage Output And High Precision

With the sustainable development of science and technology,smart phones,tablet computers and other portable electronics are becoming more and more popular,people put forward some new requirements to their charging devices.As a result,making higher efficiency,lower energy consumption,and higher performance switching power supply chargers have become a hot issue of concern.According to the current developing trend of AC / DC power management chips at home and abroad,this subject is targeted at the mid to low end market with sensitive cost and volume,and combined with the domestic semiconductor process and circuit design technical level,using standard 0.18 um high-voltage process to design an offline,high-precision,low-power power management chip,which with constant current or constant voltage output.Flyback switching power supply control chip proposed in this paper,adopting high precision primary side regulation technology,combining with low-power design and the corresponding protection circuit.It can switch between constant voltage output mode and constant current output mode automatically with the help of feedback loop according to the loading conditions.This chip set system index parameters according to requirements,and designs system-level circuits and each module circuit,then uses Cadence Hspice software to simulate and verify key circuit indicators,and finally performs tape and test verification.After testing,under 85V?265V AC input voltage,the constant current output value of this chip is 2.1A,the constant current output accuracy is not higher than ± 2.6%;and the constant voltage output value of this chip is 5V,the constant voltage output accuracy is not higher than ± 4.1%;the overall standby power consumption is not higher than 75 m W;the power density is 4.95 W / in^ 3 and the conversion efficiency is not less than 83.93% and meet EU Co C V5 Tier2 energy efficiency standards.The innovative constant current topology used in this chip not only improves the constant current accuracy to within ± 3%,but also greatly reduces the external compensation capacitor of the constant current loop(from the traditional n F capacitor to about 50 p F),which can move the externally compensate capacitor(large capacitor)into the chip(small capacitor),which reduces the application cost and enhances the performance of the chip.By comparison with the precision index of similar chips on the market,it is toilless to found that the performance of the chip designed in this article is close to that of most similar chips on the market,they can be widely used in applications such as adapters,chargers,LED constant current drivers and so on.