TI中文支持网Part Number:AM6411
HELLO :
The AM6411 CPU, with a new hardware board, has not yet been programmed with the minimum system software. Power-on testing of other voltages such as 3.3V, 1.8V, and DDR voltages are all normal. There is no VCC_CORE or VDD_0V85 voltage output. It was found that the enable function was not turned on. Further testing revealed that the VCC1V2_PG was pulled up by a 100K resistor, with 3.3V voltage at one end, but there was no voltage output at this end of VCC1V2_PG. The test also did not show any short circuit. VDD_0V85_PG was the same. After passing through U103, there was no high-level output, resulting in no voltage output for VCC_CORE. Could you please explain why VCC1V2_PG and VDD_0V85 use 3.3V and a 100K pull-up resistor? Is it related to the fact that no software was burned in? If not, what other reasons could cause this?
AM6411得CPU，硬件新贴得板 还没有烧录最小系统得软件，上电测试其它3.3V，1.8V，DDR得电压等都正常，没有VCC_CORE，VDD_0V85电压输出，发现使能没打开，进一步测试发现，VCC1V2_PG经过100K得上拉，一端有3.3V电压，VCC1V2_PG这端没有电压输出，测试VDD_0V85_PG，VCC1V2_PG也没有短路，VDD_0V85_PG也是一样，经过U103就没有高电平输出导致VCC_CORE没有电压输出，请问VCC1V2_PG，VDD_0V85为什么用3.3V 100K得上拉电阻拉不高，给上没有烧录软件有关系吗？没关系又是什么原因导致？
jianfeng cheng：
The VCC_CORE design uses a 0.75V voltage and is connected to R2 and R4. The power supply part is fine. As long as I raise the enable wire, there will be an output voltage.
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Eirwen：
已经收到了您的案例，调查需要些时间，感谢您的耐心等待。
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Vivian Gao：
有可能是因为内部阻抗高，是兆欧级别的，导致外接的上拉电阻作用不明显，没有拉到高电平。
https://e2e.ti.com/support/logic-group/logic/f/logic-forum/1278469/sn74lvc1g32-q1-impedance-of-a-b?tisearch=e2e-sitesearch&keymatch=SN74LVC1G32%2520impedance#
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jianfeng cheng：
此问题已经解决！
