Thanks to the Chip-in-Oil (CiO) technology developed at Keller, the trend toward miniaturization is now 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 lead-through feed the transmitter signals out. Together with the high-grade stainless steel housing, they form a Faraday cage around the measuring system, acting as feed-through 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 I²C inter-integrated circuit interface. 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 I2C interface up to 128 OEM transmitters can be addressed successively by one I2C master in order to call up the current pressure and temperature values from the transmitters (slaves). With an I2C output, the pressure transmitters can operate with a voltage supply of only 2,7…3,6 VDC, and they are ready to supply the current measured values 5 ms after switching on. Appropriate ON/OFF operation and low power consumption make these transmitters ideally suited for mobile applications.