各位高手:
我的電路板中snubber電路中二極管IN4007S發熱把PCB(FR-1)都燒黃了.
哪位能知道是什么原因? 2330101247285233.ppt
snubber緩沖電路中二極管燒壞
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@liangfei332
使用UF4007可以么?
看看PI的數據:
slower recovery time of the 1N4007GP causes a reverse current to flow back through the primary winding at the end of the clamping period. This partially discharges the leakage energy stored in clamp capacitor, C, and transfers some of the energy stored to the secondary, thus improving efficiency.
Diode PIN (W) POUT (W) η (%)
UF4005 36.18 30.23 83.6
1N4937 36.07 30.23 83.8
1N4007GP* 35.92 30.23 84.2
(VISHAY的是1N4007GP標了最大反向恢復時間為2uS)
slower recovery time of the 1N4007GP causes a reverse current to flow back through the primary winding at the end of the clamping period. This partially discharges the leakage energy stored in clamp capacitor, C, and transfers some of the energy stored to the secondary, thus improving efficiency.
Diode PIN (W) POUT (W) η (%)
UF4005 36.18 30.23 83.6
1N4937 36.07 30.23 83.8
1N4007GP* 35.92 30.23 84.2
(VISHAY的是1N4007GP標了最大反向恢復時間為2uS)
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@hlp330
看看PI的數據:slowerrecoverytimeofthe1N4007GPcausesareversecurrenttoflowbackthroughtheprimarywindingattheendoftheclampingperiod.Thispartiallydischargestheleakageenergystoredinclampcapacitor,C,andtransferssomeoftheenergystoredtothesecondary,thusimprovingefficiency.Diode PIN(W) POUT(W) η(%) UF4005 36.18 30.23 83.61N4937 36.07 30.23 83.81N4007GP* 35.92 30.23 84.2(VISHAY的是1N4007GP標了最大反向恢復時間為2uS)
如果使用IN4007的話,會不會對次級輸出電路造成影響?比如燒壞后面的二極管或FET啥的?
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@hlp330
看看PI的數據:slowerrecoverytimeofthe1N4007GPcausesareversecurrenttoflowbackthroughtheprimarywindingattheendoftheclampingperiod.Thispartiallydischargestheleakageenergystoredinclampcapacitor,C,andtransferssomeoftheenergystoredtothesecondary,thusimprovingefficiency.Diode PIN(W) POUT(W) η(%) UF4005 36.18 30.23 83.61N4937 36.07 30.23 83.81N4007GP* 35.92 30.23 84.2(VISHAY的是1N4007GP標了最大反向恢復時間為2uS)
我贊同hlp330前輩的說法,因為這要看當時電氣情況,一般在小功率的狀態下,若是開關二極體使用1N4007,反而可以有效的改善EMI.
以VDS波形來說的話,以前方最先量測的第一個突波(高次諧波)週期時間來計算,開關二極體的反向恢復時間要比它在慢一些,如:量測換算為600nS,可找1uS以上即可.
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