Pressure Sensor Example
The configuration shown in Figure55 is simple,and is very useful for the read out of pressure sensors.With two
op amps in this application,the dual LMV852 fits verywell.
The op amp configured as a buffer and connected at the negative output of the pressure sensor prevents the
loading of the bridge by resistor R2.The buffer also prevents the resistors of the sensor from affecting the gain of
the following gain stage.Given the differential output voltage Vs of the pressure sensor,the output signal of this
op amp configuration,VOUT, equals:
To align the pressure range with the full range of an ADC,the power supply voltage and the span of the pressure
sensor are needed.For this example a power supply of 5V is used and the span of the sensor is 100mV.
When a 100Ω resistor is used for R2,and a 2.4kΩ resistor is used for R1,the maximum voltage at the output is
4.95V and the minimum voltage is 0.05V.This signal is covering almost the full input range of the ADC.Further
processing can take place in the microprocessor following the ADC.
我的计算思路，接跟随器的电压为Vdd/2,结果算出
Vout=Vdd/2-Vs(1+R1/R2)
跟示例的结果有不少出入，请老师帮忙，谢谢！
