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WHITE PAPER PAGE 2 TE CONNECTIVITY SENSORS /// WHITE PAPER Analog and Digital Transducers — the Advantages of Both A PRESSURE TRANSDUCER THAT'S AVAILABLE IN BOTH ANALOG AND DIGITAL VERSIONS Analog and digital transducers are worlds apart in their technologies, interfaces, output signals, and the terminology used to describe and specify their operation. TE has developed an industrial pressure transducer — the M3200 — that is available in either an analog or digital configuration. Both versions share these features: ¡ Perform the same basic function of measuring and reporting the pressure of a gas or liquid in a system, pipe, or storage tank. ¡ Are identical mechanically and can be interchanged. ¡ Use the same flexible diaphragm, silicon strain gauge technology, and Wheatstone bridge to convert the applied pressure to an analog voltage signal. ¡ Digitize the analog signal for further manipulation by the transducer electronics. The similarities stop there however. Here's how the analog and digital transducers differ, not only in function, but in capabilities and benefits also. ANALOG — A CONTINUOUSLY VARIABLE OUTPUT In the analog version of the transducer, the digital signal from the internal A/D is adjusted in several ways. Calibration factors are applied to confirm the sensor meets accuracy specifications. Then temperature correction factors are used to adjust the signal and compensate for ambient temperature. Finally, zero and span calibrations are added that set the output signal in the desired range as dictated by the transducer part number. The result is then converted back to an analog signal by an internal D/A converter, run through a unity gain buffer, and sent to the output pin. The output signal is continuously variable, just like the pressure applied to the sensor. In legacy technologies such as bonded foil strain gauges, the signal was trimmed using resistors applied to a circuit board based on characterization of the sensing element over pressure and temperature. As microprocessors and ASICs became more capable and smaller, many were integrated into pressure transducers. This has resulted in better accuracy, smaller form factors, and in some cases decreased costs. The M3200 analog transducer provides a variety of output signals as illustrated in the table. P/N Code Output Range Supply Voltage Ratiometric1 2 0 to 100 mV 5.0 VDC Yes 3 0.5 to 4.5 VDC 5 ±0.25 VDC Yes 5 4 to 20 mA 9 to 30 VDC No 6 0 to 5 VDC 8 to 30 VDC No 7 0 to 10 VDC 12 to 30 VDC No 1. The output signal moves up and down in a way that is ratiometric to the supply voltage.

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