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2. 发明授权

US5811999A Power converter having switching frequency phase locked to system clock 失效
标题翻译：电源转换器具有开关频率锁相到系统时钟
公开(公告)号：US5811999A
公开(公告)日：1998-09-22
申请号：US764593
申请日：1996-12-11
申请人： George Arthur Hall , Richard Allen Smith
发明人： George Arthur Hall , Richard Allen Smith
IPC分类号： H02M3/335 , H04B15/04 , H03L7/06
CPC分类号： H02M3/33507 , H04B15/04
摘要： A circuit for synchronizing a periodic ramp signal utilized in a switching mode power converter to system clock signal. A capacitor is charged through a resistor. When a voltage across the capacitor reaches a predetermined level, the capacitor is discharged and the charging cycle is repeated, thereby generating the periodic ramp signal across the capacitor. A waveform shaping circuit shapes the ramp signal into a rectangular wave signal having a same frequency and phase as the ramp signal. A phase comparator compares a phase of the rectangular wave signal to a phase of the system clock signal for forming a phase error signal. The phase error signal controls a level of current supplied to the timing capacitor by a voltage controlled current source. When the frequency of the system clock signal is higher than the frequency of the ramp signal, the phase comparator causes the voltage controlled current source to supply additional current to the capacitor, increasing the frequency of the ramp signal. When the frequency of the system clock signal is lower than the frequency of the ramp signal, the phase comparator causes the voltage controlled current to supply less current to the capacitor, decreasing the frequency of the ramp signal. Therefore, the frequency of the ramp signal is controlled in phase locked loop to synchronize the ramp signal with the system clock signal. The synchronized ramp signal can then be utilized for controlling switching in the switching mode power converter, reducing the effects of switching noise.
摘要翻译：一种用于将在开关模式功率转换器中使用的周期性斜坡信号同步到系统时钟信号的电路。电容器通过电阻充电。当电容器两端的电压达到预定电平时，电容器被放电并重复充电周期，从而在电容器两端产生周期性斜坡信号。波形整形电路将斜坡信号形成为具有与斜坡信号相同的频率和相位的矩形波信号。相位比较器将矩形波信号的相位与用于形成相位误差信号的系统时钟信号的相位进行比较。相位误差信号通过电压控制电流控制提供给定时电容器的电流电平。当系统时钟信号的频率高于斜坡信号的频率时，相位比较器使得压控电流源向电容器提供额外的电流，从而增加斜坡信号的频率。当系统时钟信号的频率低于斜坡信号的频率时，相位比较器使得电压控制电流向电容器提供较少的电流，从而降低斜坡信号的频率。因此，在锁相环路中控制斜坡信号的频率，以使斜坡信号与系统时钟信号同步。同步斜坡信号随后可用于控制开关模式功率转换器中的开关，减少开关噪声的影响。

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