反激变换器输出同步整流驱动芯片分析与设计

发布时间：2018-03-13 16:32

  本文选题：反激变换器　切入点：同步整流　出处：《西安科技大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着电子技术的发展,芯片的供电电压越来越低,但目前供电电源的输出部分通常采用二极管整流,由于其正向导通压降较大,降低了电源效率,而采用通态电阻小的功率MOS管代替二极管实现整流,可以避免这一问题。反激变换器因其结构简单,成本低廉,在小功率领域得到广泛应用,因此,对反激变换器输出同步整流驱动控制芯片进行研究具有理论研究意义及工程应用价值。通过对反激变换器和同步整流技术工作原理及工作波形进行分析,提出了反激变换器输出同步整流驱动芯片设计方案。通过对输出同步整流MOS管的漏源电压进行采样,在同步整流MOS管漏源电压小于零时,原边开关管关断,开通同步整流MOS管;通过对流过同步整流MOS管电流进行采样放大,流过其电流小于关断阈值时,关断输出同步整流MOS管。通过在驱动芯片内置辅助电源,简化驱动芯片外围电路。辅助电源主要由电容充电模块和LDO模块组成,原边开关管导通电容充电模块储能,LDO模块为芯片低压控制电路提供稳定的输出电压;通过对带隙基准源原理的研究,设计了一个无运放的低温度系数带隙基准电压源,其温度系数为10.42ppm/℃。最后完成了一款反激变换器输出同步整流驱动芯片的设计,基于0.35um5V/60VBCD仿真库文件,采用Cadence工具对芯片内部关键电路模块进行了仿真和验证。采用所设计的驱动控制芯片搭建反激变换器系统仿真平台,对系统进行了仿真,仿真结果验证了所设计芯片的可行性。基于0.35um 5V/60V BCD设计规则文件,采用Cadence软件完成了整体电路版图设计,并通过了 DRC检查验证。
[Abstract]:With the development of electronic technology, the supply voltage of the chip becomes lower and lower. However, diode rectifier is usually used in the output part of the power supply at present. This problem can be avoided by using a power MOS transistor with low on-state resistance instead of the diode. Flyback converter is widely used in the field of low power because of its simple structure and low cost. The research on the output synchronous rectifier drive control chip of flyback converter has theoretical significance and engineering application value. The working principle and working waveform of flyback converter and synchronous rectifier technology are analyzed. The design scheme of output synchronous rectifier drive chip of flyback converter is presented. By sampling the leakage voltage of output synchronous rectifier MOS transistor, when the leakage voltage of synchronous rectifier MOS tube is less than 00:00, the primary side switch tube is turned off and the synchronous rectifier MOS tube is turned on. By sampling and amplifying the current of the synchronous rectifier MOS tube, the output synchronous rectifier MOS tube is turned off when the current is less than the turn-off threshold. The auxiliary power supply is mainly composed of capacitor charging module and LDO module. By studying the principle of bandgap reference source, a low temperature coefficient band-gap voltage reference without operational amplifier is designed. The temperature coefficient is 10.42 ppm / 鈩，

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