标题: 754主板过温保护故障(已经解决) [打印本页] 作者: fxchby 时间: 2008-4-28 23:50 标题: 754主板过温保护故障(已经解决) 辉煌K8VM-800主板,上假负载上电一切正常,十几秒后,俄罗斯测试卡上的复位灯熄灭,测CPU Vcore \Reset\PG都为0V,点复位键不能复位,测复位键开关电压为0V,长按开关键关闭电源后可以重新触发,但是一开始就无复位;只有拔掉电源后重新接上后才能有复位十几秒,重复前面的故障现象.跑电路知,复位键一路直接连接到时钟IC,一路连接到W83304D的第5脚Fault#.割断通向时钟IC的线路,故障依存.测Fault#电压为0V，W83304D已经被关闭。查W83304D的datasheet得知,第5脚Fault#是起保护作用的,继续跑电路得下面的电路图.其中,关于754 CPU的THERMTRIP_L引脚在754 Datasheet中说明如下:
3.7 THERMTRIP_L
Both lidded and lidless processors provide a hardware enforced thermal protection mechanism. When the processor’s die temperature exceeds a specified temperature, the processor is designed to stop its internal clocks and assert the THERMTRIP_L output.
THERMTRIP_L assertion is only valid when PWROK is asserted and RESET_L is deasserted.
THERMTRIP_L assertion indicates the processor die temperature has exceeded normal operating parameters. PWROK must be deasserted in response to a THERMTRIP_L assertion to enable proper processor operation.
Once asserted THERMTRIP_L remains asserted until RESET_L is asserted.
If the processor’s die temperature still exceeds the thermal trip point when RESET_L is deasserted,
THERMTRIP_L will immediately be reasserted and the processor’s internal clocks will be stopped.
主要意思是说THERMTRIP_L是起过温保护,当754CPU的核心温度die temperature高达到某一程度时,该引脚就会被置为有效.
奇怪的是，不上真CPU，不管上不上假负载，都会出现过温保护……查到这里，不知如何下手了………………
