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关于开关电源电感在大电流是发出吱吱声的分析
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Why noise output from choke?
Why the output choke got noise sound when the 3D mark running?
The reason is the loading change frequency between 50Hzand 20KHz,
The core and wire of coke will vibrate by loading change frequency,the noise of chokewill follow the frequency , and the loading change level will change the noise dB.
If the vibration frequency out of this range or the noise less 10 dB, we can't hear it.
Many M/B gotsame result,
Whenvibration noisehappen on transientorloading change only,
And thethermalof choke never getting hot , it's normal.
On the static load, the chokeshould silence.
If on the static load , the choke got noise and also getting hot, that's abnormal.
Poor the gain of feedback and poor transient response also can reduce the noise.
Like slow down the switching frequency , reduce the gain of compensation, or use slowly response time, it will help to reduce the noise. But the change will impactto the transient result.
For example : when the loading be changed by 50A/us, the output chokefollow by 10A/us, it's need 5 us togotthe change.
If output can follow fast than 50A/us, than the change time will short and the vibration will heavy , the noise dB will increase .
Increase switching frequency, change the vibration frequencysome times reduce the noise, But the change will impactto the thermal of Upper Mosfet.
Summary:
The choke silence on static load, thermal stable on static and loading change, getting noise from loading transient, It's mean normal. Nothing changerecommend.
If the noise is not acceptable by customer, a little lower switching frequency will smaller impact to transient and improve the thermal of high sideMosfet.
But the change doesn't mean the noise will be gone, some loading c frequency change or heavy current change slew rate, the noise will possible happen again.
Why the output choke got noise sound when the 3D mark running?
The reason is the loading change frequency between 50Hzand 20KHz,
The core and wire of coke will vibrate by loading change frequency,the noise of chokewill follow the frequency , and the loading change level will change the noise dB.
If the vibration frequency out of this range or the noise less 10 dB, we can't hear it.
Many M/B gotsame result,
Whenvibration noisehappen on transientorloading change only,
And thethermalof choke never getting hot , it's normal.
On the static load, the chokeshould silence.
If on the static load , the choke got noise and also getting hot, that's abnormal.
Poor the gain of feedback and poor transient response also can reduce the noise.
Like slow down the switching frequency , reduce the gain of compensation, or use slowly response time, it will help to reduce the noise. But the change will impactto the transient result.
For example : when the loading be changed by 50A/us, the output chokefollow by 10A/us, it's need 5 us togotthe change.
If output can follow fast than 50A/us, than the change time will short and the vibration will heavy , the noise dB will increase .
Increase switching frequency, change the vibration frequencysome times reduce the noise, But the change will impactto the thermal of Upper Mosfet.
Summary:
The choke silence on static load, thermal stable on static and loading change, getting noise from loading transient, It's mean normal. Nothing changerecommend.
If the noise is not acceptable by customer, a little lower switching frequency will smaller impact to transient and improve the thermal of high sideMosfet.
But the change doesn't mean the noise will be gone, some loading c frequency change or heavy current change slew rate, the noise will possible happen again.
晕哦， 怎么是英文啊
呵呵，金山快议啊
可以看得明白，谢谢楼主了
好像在一些器件公司提供的设计手册上看看过。
好像很难解这个问题，也只能调一下 f 和 Compenstion。
不错,还可以熟悉一下英语
The issue just happen now.ths
你看看Compenstion那边对地的MLCC电容的值是否过小
我是中国人看不懂 e 文！
学习啦！。
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