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DS3984推挽式CCFL驱动电路

最近用DS3984做了个4灯管的逆变器.
按照DATASHEET上的电路设计的.
DS3984规格书
673411197124399.pdf

灯管频率50KHZ,PWM频率148HZ
但是输出波形不是纯正弦波,而且在低亮度时,灯管有点闪.

请教,有没有用过3984的,给些建议.

LCM脚波形(软启动波形)
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/60/673411197123835.jpg?x-oss-process=image/watermark,g_center,image_YXJ0aWNsZS9wdWJsaWMvd2F0ZXJtYXJrLnBuZz94LW9zcy1wcm9jZXNzPWltYWdlL3Jlc2l6ZSxQXzQwCg,t_20');}" onmousewheel="return imgzoom(this);">
LCM脚波形(启动后)
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/60/673411197124219.jpg?x-oss-process=image/watermark,g_center,image_YXJ0aWNsZS9wdWJsaWMvd2F0ZXJtYXJrLnBuZz94LW9zcy1wcm9jZXNzPWltYWdlL3Jlc2l6ZSxQXzQwCg,t_20');}" onmousewheel="return imgzoom(this);">
MOS管波形
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/60/673411197124285.jpg?x-oss-process=image/watermark,g_center,image_YXJ0aWNsZS9wdWJsaWMvd2F0ZXJtYXJrLnBuZz94LW9zcy1wcm9jZXNzPWltYWdlL3Jlc2l6ZSxQXzQwCg,t_20');}" onmousewheel="return imgzoom(this);">
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2007-12-10 15:48
查了些资料
673411197199963.pdf

变压器的匝数比可能不对

查看美信的资料后,决定把输入电压降低试试

随着输入电压的降低,MOS管占空比增大,波型(LCM)有些改善
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/60/673411197200782.jpg');}" onmousewheel="return imgzoom(this);">

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/60/673411197200845.jpg');}" onmousewheel="return imgzoom(this);">

5V输入电压时
LCM波形
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/60/673411197200264.jpg');}" onmousewheel="return imgzoom(this);">

MOS管源极波形
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/60/673411197200368.jpg');}" onmousewheel="return imgzoom(this);">

更改后,5V供电的灯管亮度比12V供电还高,变压器温度也降低了.

但是,低亮度时,闪烁的问题还是没有解决.

另外在输出电压上串一个30pF的高压电容后,灯管反而点不亮了.

请高手指点一下!
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