7V200A电源,在脉冲式开关负载下有叫声.
脉冲频率100Hz- 1KHz,占空比10%,上升沿10uS.
在开关电源输出与负载间串入MOS管作为负载开关,用以上脉冲控制MOS管开关.
测误差放大器输出波形,可以看到误差放大器输出已是低频间歇振荡.
![](http://u.dianyuan.com/bbs/u/72/388311228890280.jpg?x-oss-process=image/watermark,g_center,image_YXJ0aWNsZS9wdWJsaWMvd2F0ZXJtYXJrLnBuZz94LW9zcy1wcm9jZXNzPWltYWdlL3Jlc2l6ZSxQXzQwCg,t_20)
500) {this.resized=true; this.width=500; this.alt='这是一张缩略图,点击可放大。\n按住CTRL,滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/72/388311228890280.jpg?x-oss-process=image/watermark,g_center,image_YXJ0aWNsZS9wdWJsaWMvd2F0ZXJtYXJrLnBuZz94LW9zcy1wcm9jZXNzPWltYWdlL3Jlc2l6ZSxQXzQwCg,t_20');}" onmousewheel="return imgzoom(this);">
上图中上面波形是负载开关控制信号,频率100Hz,5V/DIV.
上图中下面波形是误差放大器输出波形,有间歇.2V/DIV
![](http://u.dianyuan.com/bbs/u/72/388311229000524.jpg?x-oss-process=image/watermark,g_center,image_YXJ0aWNsZS9wdWJsaWMvd2F0ZXJtYXJrLnBuZz94LW9zcy1wcm9jZXNzPWltYWdlL3Jlc2l6ZSxQXzQwCg,t_20)
500) {this.resized=true; this.width=500; this.alt='这是一张缩略图,点击可放大。\n按住CTRL,滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/72/388311229000524.jpg?x-oss-process=image/watermark,g_center,image_YXJ0aWNsZS9wdWJsaWMvd2F0ZXJtYXJrLnBuZz94LW9zcy1wcm9jZXNzPWltYWdlL3Jlc2l6ZSxQXzQwCg,t_20');}" onmousewheel="return imgzoom(this);">
上图中上面波形是负载开关控制信号,频率100Hz,5V/DIV.
上图中下面波形是电源输出波形.2V/DIV.
在此工作条件下,电源环路已严重失去平衡.
请大家指教如何改善?