MB主板上电过程.ppt
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1、MB主板上電過程,前言,電腦的開機只需要對著Power鍵輕輕一按即可.可這一按具體是如何使電腦能開機工作的呢?它的整個過程是怎樣的?以下分幾個部分做講解,Content,開機上電動作圖解主板的電壓定義主板的主要開機信號介紹主板開機上電過程(波形和電路),PWRBTN,Slp-s3(+),Pson#(-),+5v,+3v,+12v/-12v,+5v,+3v,Power ok,NB_ RESET,Reset,SB,NB,CPU,POWER,SUPER I/OOR AS016,Cpu rst,Intel chipset power on sequence,Pwr ok,Power Sequence,
2、MB Power Sequence,主板基本電壓(電源控制IC),主板基本電壓有5個,其他電壓都是由這5個基本電壓轉換而得.,主板基本電壓,ACPI的Global States分四個狀態G0G1G2G3,ACPI表示高級配置和電源管理介面對於Windows2000,ACPI定義了Windows、BIOS和系統硬體之間的新型工作介面。這些新介面包括Windows 控制電源管理和設備配置的機制。,主板基本電壓,狀態電壓種類有3種1.Main power:S0/S12.Dual power:S0/S1/S33.Standby power:S0/S1/S3/S4/S5,詳細參考附件:,Main Pow
3、er,Main power的產生由SLP_S3#去控制。按Power Button PWRBTN#拉low 通知SIOSIO告知NB NB送出SLP_S3#(此時SLP_S3#為高電平)PSON#被拉low Power Supply產生Main Power.,Power-up(Main Power),CH1:+12VCh2:+5VCh3:+3V,Main power(+12V,+5V,+3V)almost ramp up at the same time.The main power ramp behavior depends on the power supply design.,Stand
4、by Power,1,在MB上,power supply只提供+5VSB一種standby電壓,其他standby power都由它轉出來的。2,Standby power上電(插上power cord)主板就會有,但其提供的電流有限。,Dual Power,Dual power由standby power和main power提供,他存在於S0,S1,S3這幾種狀態下,由Gate信號去控制哪一個power輸出。,主板信號簡介,RTCRST#RSMRST#PWRBTN#SLP_S3#PS_ON#PWROKPLTRST#,RTCRST#,Battery,3.0V,BATT,2.6V,G3 Sta
5、te,BATT comes from BATTERY at G3 state.So BATT will be 2.6V at G3 state.BATT comes from+3VSB at S5 state.So BATT will be 2.9V at S5 state.,S5 State,2.9V,RTCRST#有效:在G3狀態時,拔掉battery,此時SB收到低電平,會清掉COMS 內容;若要給主板維持時間或CMOS內容,RTCRST信號需要是高電平.,+3VSB,S5 State,+5VSB,RSMRST,After plugging power cord,+5VSB ramps
6、up.+3VSB is regulated from+5VSB.32ms after+3VSB ramps above VTRIP(2.2V),RSMRST asserts.RSMRST will re-assert after AC power loss,which acts like a wake up event of SB and causes the de-assertion of SLP_S3#to turn on the system.,RSMRST#,Resume reset active表示所有的standby power都OK.,RSMRST#:Resume Well Re
7、set,this signal is used for resetting the resume power plane logic.,AUXOK Logic Example:,Let VPQ3.1 ramps up slower than+3VSB.It is to meet the spec that RSMRST(AUXOK)needs to ramp up after VTR is ready with a delay(20ms for SB600).To precisely estimate the resulting delay from+3VSB to AUXOK,we need
8、 to implement the RC charge formula.,VC,If VCC=3.3V,assuming 20ms is needed:t=RC=20ms VC(20ms)=2.08V VC(18.63ms)=2VIf VCC=5V,assuming 20ms is needed:2.t=RC=20ms VC(20ms)=3.16V VC(10.22ms)=2V RC is chosen by substituting VC(t),VCC,t and solve for RC.,RSMRST#,PWRBTN#,PWRBTN#:Power Button,#:代表低電平有效,PWR
9、BTN#,Pin6 and pin8 is connected to the power button on the chassis.Pressing power button generate a low pulse to SB and SIO.Power button can be programmed to generate suspend,hibernate or shut-down event.Generally PWRBTN#of SB is internal pulled high,R1336 is reserved to avoid internal pull-high mal
10、function.This must be pulled to standby power.,5.CB918 must be installed:1.Debounce,2.Prevent ESD from directly going into SB and SIO.1000PF is a commonly used value.6.To achieve better ESD resist performance,CB918 should be placed near front panel header.,SLP_S3#,SLP_S3#:Sleep Control,SLP_S3#is for
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