请问,采用TPS62170采用R1=390K,R2=180K输出2.5V的电压,没有接负载的时候,输出电压为+2.5v,但接上负载后,输出电压变为3.24V,不明白怎么回事,以为芯片坏了,换了新的还是老样子。
什么原因导致输出电压变高了?谢谢
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请看datasheet这段话
Also sensitive nodes like FB and VOS should be connected with short wires, not nearby high dv/dt signals (e.g.
SW). As they carry information about the output voltage, they should be connected as close as possible to the
actual output voltage (at the output capacitor). Signals not assigned to power transmission (e.g. feedback divider)
should refer to the signal ground (AGND) and always be separated from the power ground (PGND).
不确定的是:如果和后面的电路断开测试输出电压为2.5V,没有问题。但是连接负载以后电压变为3.24V左右,疑惑在于接负载了电压变低好理解,但变高是什么原因了?什么会导致这升压?
1、PCB如何有问题的话,我觉得应该不接负载的时候就可以显现出来。
2、如果负载有问题的话,那负载上什么样的电路会导致这个情况(这个2.5V电压是给Xilinx的FPGA的配置和IO管脚供电的)。
3、板子也有3.3V的供电,是不是2.5V那里和3.3V短路了?测量发现2.5v和3.3v无短路。
4、测试输出端和地,发现电阻为160ohm。
谢谢!
确实比较疑惑为什么会升压?