[广达案例】-电源毛刺波形 分析过程

会员478826

Glitch Issue

* 5V_RUN, 5V_SUS, and 3V_SUS have glitch issue in system shut down. Following are the waveforms.

  

CH1:+5V_RUN

CH2:+3.3VSUS

CH3:+5V_SUS

file:///C:/Documents%20and%20Settings/ljjvip/Application%20Data/Tencent/Users/274482736/QQ/WinTemp/RichOle/_4J%7B6_)OMFX5ZWP69E%7D2%60O2.jpg

*Compare ISL6236 and MAX8778 controller for this issue. Following is +5V_RUN schematic.

file:///C:/Documents%20and%20Settings/ljjvip/Application%20Data/Tencent/Users/274482736/QQ/WinTemp/RichOle/25MV$3A3LL%7BINWZ%608%7BG7BM7.jpg

1. Controller of +3.3_ALW and +5V_ALW: ISL6236

CH1:+5V_ALW

CH2:+15V_ALW

CH3:+5V_ALW2

CH4:+5V_RUN

[img=675,418]file:///C:/Documents%20and%20Settings/ljjvip/Application%20Data/Tencent/Users/274482736/QQ/WinTemp/RichOle/ZBBVLI]55Z6J[QP$Q2PEJ59.jpg[/img]


file:///C:/Documents%20and%20Settings/ljjvip/Application%20Data/Tencent/Users/274482736/QQ/WinTemp/RichOle/0)GRC4(EDPBY(1JVV(CK~SR.jpg

The waveforms show the glitch root cause. When +5V_ALW2 down to zero, the +15V_ALW is 5.16V and +5V_ALW is 3.46V. The PQ44 will be turn on, then cause this issue.

[Summary]: When system shut down, +5V_ALW2 down  to zero immediately for ISL6236 IC.

So ISL6236 has glitch issue.

[Solution]: Put PR65 into 10ohm.When +3.3V_ALW, +5V_ALW and +5V_ALW2 shut down, Vcc(pin3) of ISL6236 exist 3.6V. In the other words,Vcc(pin3) will appear 3.6V as long as Vin(pin6) present. So +5V_ALW2 will exist a voltage velua(about 2.8V) in shut down. This issue can be solved when put PR65 into 10ohm.

[img=768,330]file:///C:/Documents%20and%20Settings/ljjvip/Application%20Data/Tencent/Users/274482736/QQ/WinTemp/RichOle/L)TCW_XPB%60CO%252NNS938[WB.jpg[/img]

会员393519

在哪复制的吧

会员631672

看情况是为了转正的，无语

会员351551

楼主是搞FMEA的吧？同行啊