【作者】 田锦明；

【导师】 王松林；

【作者基本信息】 西安电子科技大学 ， 电路与系统， 2006， 硕士

【摘要】 本文的主要工作是设计一种单片电源管理集成控制电路,该集成电路采用跨周期调制(SCM)模式与脉宽调制(PWM)模式相结合的工作方式，来减小功率损耗,需要较少的外部元件即能构成完整的开关电源。控制器内部电路可工作在40KHz、60KHz或100KHz三种不同的固有频率,内部集成了耐压450V的功率LDMOS,该场效应管能保证无能量损失或低能量损失的开启过程。最大驱动输出电流250mA,芯片的最高工作效率可达90%以上。由于采用电流模式控制,极大地简化了逐个脉冲控制,实现了可靠的廉价离线变换器的设计。输出接额定负载时芯片工作在PWM模式。当输出功率需要量减小时,该集成电路自动地进入所谓跨周期模式,以便在轻负载条件下达到极好的效率。因为这种情况发生在低峰值电流条件下,所以不会产生听得到的音频噪声。电路内部还有一个有效的过载保护电路,当出现过载时,停止输出脉冲而进入安全模式；当故障消除后,控制器恢复,并返回至正常工作状态。具有迟滞功能的过温保护电路,使供电更加安全。并具有过压、欠压保护功能。更多还原

【Abstract】 The main work of this paper is to design a switching power controller with low power dissipation. The evolution of controlling mode combined both advantages of Pulse-Width Modulation (PWM) and Skip-Circle Modulation (SCM) mode was adopted to decrease the power loss. Cooperating with simple periphery component, a full switch power supply is formed. With an internal structure operating at a fixed 40 kHz,60 kHz or 100 kHz switching frequency, the controller features a high-voltage start-up Lateral double diffused MOS (LDMOS) with breakdown voltage exceed 450V which ensures a clean and loss-less startup sequence. The convertor has the capability of 250mA peak drive current and the efficiency of this convertor is up to 90%.Its current-mode controlling naturally provides good audio-susceptibility and inherent pulse-by-pulse control. The system worked at normal PWM mode at heavy load.When the current set-point falls below a given value, e.g. the output power demand diminishes, the controller automatically enters the skip cycle mode and provides improved efficiency at light loads while offering excellent performance in standby conditions. Because this occurs at a user adjustable low peak current, no acoustic noise takes place. The controller also includes an efficient protective circuitry which, in presence of an output over load condition, disables the output pulses while the device enters a safe burst mode, trying to restart. Once the default has gone, the device auto-recovers. Finally, a temperature shutdown with hysteresis and the function of UVLO help building safe and robust power supplies.更多还原