Embedded Pressure Measurement by Keller

  • December 20, 2021
  • Keller America Inc
  • Sponsored
Embedded Pressure Measurement by Keller
Embedded Pressure Measurement by Keller

The LC and LD lines from Keller employ a revolutionary CIO (Chip-In-Oil) technology that gives new meaning to embeddable pressure measurement. This unique technology simplifies OEM pressure measurement integration, which shortens time-to-market and reduces R&D and production costs.   

These new OEM transmitters combine microprocessor-based signal conditioning technology with a proven piezoresistive silicon pressure sensor, all within a miniature, environmentally-sealed housing that provides either an analog or digital output signal.

In the analog version, known as Series 4 LC...9 LC, the signal processing ASIC is fitted behind the sensing diaphragm, adjacent the pressure sensor, under oil, and with the exclusion of air. This yields a host of advantages in terms of application: all the key measurement and signal conditioning components are now protected against degradation due to humidity and condensation. The interior wiring is implemented with short, lightweight gold bonding wires, external electrical connections are made via sintered-in pressure-resistant feedthrus.

Together with the high-grade stainless steel, Hastelloy C-276, or 6Al-4V titanium housing, they form a Faraday cage around the pressure sensor + ASIC, acting as feed-through capacitors, resulting in a miniature pressure transmitter that is not only all-media capable but also RFI resistant up to field strengths of 250 V/m and for frequencies of up to 4 Ghz.

The 4 LC...9 LC pressure transmitters feature a ratiometric analog voltage output with an internal sampling rate that results in a dynamic range of 2 kHz. 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 and less than 8 mA current consumption, the output signal is specified as 0,5 ... 4,5 V. The transmitters provide constant protection against overvoltage and reverse polarity on all lines up to ±33 VDC and are fully calibrated to yield exceptional Total Error Band performance over a wide compensated temperature range (varies by type).

Alternatively, the Series 4LD...9LD  provides a digital-integrated circuit interface (I²C). The I²C interface is regarded as the serial standard in embedded systems. Up to 128 OEM 4LD...9LD transmitters can be addressed successively by one I²C master, enabling retrieval of both pressure and temperature values from the transmitters (slaves). The 4LD….9LD transmitters can operate with a voltage supply of only 2,7…3,6 VDC at less than 3 mA current consumption and they respond to data requests with current values <5 ms after start up, making them ideally suited for mobile or remote, battery-powered applications. As with the LC series, the 4LD…9LD are fully calibrated at the factory, resulting in a true “plug-and-play” solution for the system designer.

The available full scale pressure ranges for the LC series extend from 30 to 15000 PSI Full Scale and for the LD from 30 to 3000 PSI Full Scale. In both series, the size envelope ranges from Ø11 x 4.2mm in length up to Ø19 x 5mm in length, resulting in an ideal solution for many OEM applications.

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