Voltage requirements for pressure sensors

Generally ordinaryThe output of the pressure sensor is an analog signal, with a close range full range output voltage of 100-150mV and an output current of 0-0101mA The voltage of the remote output signal will decay, and current signal output should be used. After amplifying the current through a pressure transmitter, a current signal below 20mA can be output. This will double the price.

In addition, digital signals and frequency signals can only be obtained after A/D and V/F transformations. Both constant current and constant voltage sources are commonly used as excitation sources for sensors. The two incentive methods are different and have different effects.

Constant current source excitation is beneficial for compensating thermal sensitivity drift.

Because the temperature coefficient of the bridge arm resistor is positive, while the sensitivity temperature coefficient is negative. The temperature coefficient of the output signal voltage under constant current source excitation is the algebraic sum of the two. And constant voltage excitation cannot directly provide sensitivity temperature compensation effect. But when using a constant voltage source excitation, a thermistor or diode can be connected in series outside the bridge to compensate for thermal sensitivity drift. When using a constant current source excitation, this sensitivity compensation method does not work. It can be seen that constant voltage source excitation and constant current source excitation cannot be interchanged with each other at will.

Constant current source excitation is used for general precision measurement. When excited by a constant voltage source, the measurement accuracy depends on the accuracy of the constant voltage source voltage stabilizing device.

In addition, the excitation power supply of the pressure sensor can be divided into proportional excitation and fixed excitation. The former connects the pressure transducer bridge directly to the power supply, and when the power supply changes,The sensitivity and zero point of the pressure sensor change accordingly. The latter has a reference voltage internally, and the pressure sensor bridge is powered and excited by the reference voltage. The reference voltage is constant and independent of the power supply voltage. As long as the power supply voltage changes within a specified voltage range, the reference voltage remains unchanged. Therefore, the output of the sensor remains unchanged and is not affected by the power supply voltage.

Pressure sensors can be powered by batteries, but more commonly, they use DC regulated power technology. When powered by a battery, the noise is low, but as the battery is used, the supply voltage gradually decreases, especially when the sensor is stimulated proportionally, the sensitivity gradually decreases. This will result in inaccurate readings. Therefore, compensation methods should be adopted (such as using a common battery power supply for pressure sensors and A/D converters), or using low-power, low current pressure sensors with a long lifespan battery, or connecting the power supply when measuring pressure. After the measurement is completed, the battery should be turned off to save energy. After replacing the battery with a new one, the pressure sensor needs to be recalibrated and calibrated. This is because there are certain differences in the electromotive force and internal resistance of batteries of different brands. The change in excitation voltage of the pressure sensor's bridge can cause a change in sensitivity.