| With the continuous development of semiconductor technology and process,the electronics market has been booming.Smart phones as the representative of the portable intelligent terminal have been widely used and bring convenience to people's lives.As the function of the smart phone is becoming more and more powerful,the frequency of use of intelligent devices is also increasing,which puts forward higher requirements for the power supply.There is no doubt that how to improve the charging speed to make up for the lack of battery supply has become a new challenge and new trend in the development of smart phones.Following the market demand and development trend,this paper focuses on the research of the basic theory and related protocols of quick charge technology,and solves the related technical difficulties.A power supply interface chip XD1786 compatible with quick charge technology is designed.In view of the problems of traditional charge pump shoot-through phenomenon,a high-voltage cross-couple charge pump with non-overlapping clock is proposed.This charge pump has a wide input range and a small output ripple,and can effectively avoid the shoot-through current phenomenon,thus improve the voltage gain and efficiency.At the same time,a level shift circuit with negative feedback regulation ability is designed,which can follow input voltage,and has high anti-interference ability.In addition,through studying the basic theory of translinear loop,the principle is extended from the bipolar transistor translinear loop to the translinear loop composed of MOS transistors,and applied to the analysis and design of analog integrated circuit,thus simplifying the calculation of non-linear circuits.This paper systematically introduces the whole design process of XD1786.Firstly,this paper introduces the basic theory of quick charge technology and related protocols,and the problems brought by the quick charge technology are studied.By comparing various implementations of quick charge,this paper presents a more reasonable implementation scheme of quick charge.Secondly,according to the typical application,the electrical characteristics of the chip are determined,and the system structure and function of the chip are designed.Then,this paper describes the function description,the principle analysis and circuit design of some core sub-modules in the chip,and finally verified by simulation.And then the whole function of the chip is verified by pre-simulation and post-simulation,and the layout of XD1786 is designed.Finally,the function of the chip is verified by the actual test,and the test results are analyzed.XD1786 is a USB mobile device charger interface IC which implements the QC 2.0 or QC 3.0 specification for adaptive voltage battery charging.XD1786 can automatically select the appropriate output voltage,thereby reducing the battery charging time and system charging loss,and can automatically detect whether a connected PD is QC 2.0 or QC 3.0 capable before enabling output voltage adjustment.If a PD that is not compatible with quick charge specification,XD1786 disables output voltage adjustment to ensure safe operation.XD1786 built-in adaptive output overvoltage protection(AOVP),secondary over-temperature protection(SOTP),output soft short circuit protection(OSSP)and other protection circuits to ensure the safe and stable operation of the system.XD1786 circuit and layout design is based on 0.35?m 24 V BCD process,using Cadence software and Spectre simulator for simulation verification,and testing the flow out of the sample,the test results show that the performance of the chip can meet the design requirements. |
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