The
SSP1492 (
Product
Brief) will interface directly with the
Piezoresistive Bridge Outputs provided by some
Pressure sensors. The SSP1492 utilizes a unique frequency mode data acquisition technique which converts sensor output into a frequency-based signal by placing the sensor element into a resistance-capacitance (RC) oscillator as shown in Figure 1. The oscillator circuit consists of a comparator with a positive feedback loop to create an oscillator which converts the time-varying sensor signal into a square wave with a varying time period. This signal can be counted and digitized into a value that is proportional to the oscillator frequency, and in turn, proportional to the sensor’s measurement. In the RC oscillator configuration, the sensor is introduced as a variable resistor (R) with an external fixed capacitor (C) in the circuit. A period counter unit (see Figure 2) demodulates and digitizes the output signal from the sensor oscillator section, and can measure two parameters of time-varying signals: cycle period and pulse width. The sensor data converter has scalable dynamic range, accuracy and speed and can easily be scaled from less than 8 to over 24 bits of conversion resolution.
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