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求教UCC28019的一些基本問(wèn)題

用UCC28019 做PFC，芯片還沒(méi)有到，一直在研究datesheet。有幾個(gè)問(wèn)題想問(wèn)一下

1

 

對(duì)于芯片的Input Brown-Out Protection(IBOP)，我的理解是可以設(shè)置電阻分壓讓芯片在你想的電壓時(shí)使進(jìn)入IBOP模式，但不知道進(jìn)入IBOP模式后芯片會(huì)怎樣操作

This prevents unwanted sustained system operation at or below a“brown-out” voltage, where excessive line current could overheat components. In addition, because VCC bias isnot derived directly from the line voltage, IBOP protects the circuit from low line conditions that may not triggerthe VCC UVLO turn-off.

還有低電壓時(shí)芯片會(huì)發(fā)生什么誤動(dòng)作，使電流過(guò)大？ 這個(gè)跟VCC的UVLO好像沒(méi)什么關(guān)系吧？因?yàn)槭欠珠_(kāi)供電的。

 

2

ISENSE腳電流峰值控制是什么原理 為什么計(jì)算時(shí)候Vsoc取0.66?

 

3

ICOMP 和VCOMP的兩個(gè)補(bǔ)償腳怎么用的，數(shù)據(jù)手冊(cè)上電阻電容直接接地，是閉環(huán)控制嗎？

 

 

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higel
LV.8
2
2013-08-24 09:16

1. 進(jìn)入Brown-Out后IC的輸出會(huì)關(guān)閉，直到IBOP腳電壓升高到VINSENABLE_th，IC恢復(fù)輸出

低壓時(shí)，要是沒(méi)有Brown-Out，電源的輸入電流會(huì)增大，系統(tǒng)的元件器應(yīng)力增大

Brown-Out與VCC UVLO不是同一回事，他們之前沒(méi)關(guān)系的

建議你仔細(xì)了解一下Brown-Out的作用


2. 峰值電流控制原理自己百度一下

Vsoc計(jì)算時(shí)取0.66V：（以下datasheet原文19頁(yè)）

The current sense resistor, RSENSE, is sized using the minimum threshold value of Soft Over Current (SOC), VSOC(min) = 0.66 V. To avoid triggering this threshold during normal operation, taking into account the gain of the internal non-linear power limit, resulting in a decreased duty cycle, the resistor is typically sized for an overload current of 25% more than the peak inductor peak current.


3. 補(bǔ)償電路，詳細(xì)請(qǐng)了解補(bǔ)償電路Type-I、Type-II


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大氣球
LV.2
3
2013-08-24 20:19
@higel
1.進(jìn)入Brown-Out后IC的輸出會(huì)關(guān)閉，直到IBOP腳電壓升高到VINSENABLE_th，IC恢復(fù)輸出低壓時(shí)，要是沒(méi)有Brown-Out，電源的輸入電流會(huì)增大，系統(tǒng)的元件器應(yīng)力增大Brown-Out與VCCUVLO不是同一回事，他們之前沒(méi)關(guān)系的建議你仔細(xì)了解一下Brown-Out的作用2.峰值電流控制原理自己百度一下Vsoc計(jì)算時(shí)取0.66V：（以下datasheet原文19頁(yè)）Thecurrentsenseresistor,RSENSE,issizedusingtheminimumthresholdvalueofSoftOverCurrent(SOC),VSOC(min)=0.66V.Toavoidtriggeringthisthresholdduringnormaloperation,takingintoaccountthegainoftheinternalnon-linearpowerlimit,resultinginadecreaseddutycycle,theresistoristypicallysizedforanoverloadcurrentof25%morethanthepeakinductorpeakcurrent.3.補(bǔ)償電路，詳細(xì)請(qǐng)了解補(bǔ)償電路Type-I、Type-II
謝謝！
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