如上图,这是ST公司的STM32F373-EVAL评估版上的用于测量温度的电路。小弟愚钝,看不懂这个电路,请问如何计算PT100的电压?pt100是温度传感器,热敏电阻之类的。
ST官方文档说运算放大器A1的增益为1,不知道为啥? 下面是官方文档的解答。看不懂。
The operational amplifier, A1, and the resistors R1 to R5 form a differential amplifier with a
differential gain (GA1).
Due to the resistor values chosen, GA1 is equal to 1. This is known because the resistor
bridge, R1 and R2, connected to VDD is equivalent to the VDD/2 generator where R1/2 = R
internal resistor.
The voltage on Rref is given in Equation 2 to Equation 5.
Due to the resistor values chosen, GA1 is equal to 1. This is known because the resistor
bridge, R1 and R2, connected to VDD is equivalent to the VDD/2 generator where R1/2 = R
internal resistor.
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这段如何理解?VDD---R1----R2---是可以等效成VDD/2---R网络,可是这和A1的增益什么关系?