Thanks to the Chip-in-Oil (CiO) technology developed at Keller, the trend toward miniaturization is now becoming a reality. In our Series 4 LC…9 LC pressure transmitters, the special ASIC for signal processing is fitted directly next to the pressure sensor, in the same housing, under oil, and with the exclusion of air. This yields a host of advantages in terms of application: all the key pressure measurement components are now protected against the risks from humidity and condensation. The interior wiring is implemented with short, lightweight bonding wires, while sintered-in pressure-resistant glass leadthroughs feed the transmitter signals out. Together with the high-grade steel housing, they form a Faraday cage around the measuring system, acting as feedthrough capacitors. This makes the CiO technology absolutely RFI resistant up to field strengths of 250 V/m and for frequencies of up to 4 GHz.

Series 4 LC…9 LC pressure transmitters offer two output signals: a ratiometric analog voltage output and a digital inter-integrated circuit interface (I2C). The ratiometric signal eliminates the need for an expensive voltage reference in the support electronics to the A/D converter, with no additional effort and expense for compensation and calibration. For a voltage supply of 5,0 V, the output signal is specified as 0,5 … 4,5 V. The transmitters provide constant protection against overvoltage and polarity reversal on all lines up to ±33 VDC.

With an analog output, the transmitters can be used at temperatures of between -40 °C and +150 °C, and with an I2C output the range is from -40 °C to +80 °C. The full scale pressure ranges for the analog version extend from 2 bar to 1’000 bar, and for the digital version from 2 bar to 200 bar. The internal sampling rate offers a very good dynamic range of 2 kHz. Low power consumption during continuous operation is another benefit. In this regard, the digital version requires less than 3 mA, and the analog version requires about 8 mA .