Keller LD series miniature combination pressure and temperature transmitter

A fully functional digital combination transmitter for pressure and temperature, claimed to be the smallest available, has been launched by Keller AG für Druckmesstechnik.

In the LD series, all the electronic components are accommodated in a laser-welded stainless steel housing filled with silicone oil. Measuring only 11 mm in diameter, the housing contains the sensor technology, the compensation coefficients, the digital signal processing and the I2C interface for simple, loss-free integration into higher-level systems.

Made of stainless steel or Hastelloy, the housing not only acts as a Faraday cage but also offers appropriate pro­tection against electromagnetic radiation and all potential environmental influences. Due to the chip-in-oil technology, extremely short signal paths with exceptionally high impact and vibration resistance are realised.

Six standard measurement ranges extend from 1 to 200 bar abs. with a compensated temperature range of -10°C to +80°C. Accuracy is rated as better than ±0.15%FS, and a total error band of less than ±0.5%FS is attained between 0°C and 50°C. The temperature measurement accuracy is ±2 K.

Transmitters in the LD series are optimised for battery-powered applications: during A-to-D conversion, current consumption is ~1.5 mA, dropping to ~0.1 μA in idle mode. The supply voltage range of 1.8-3.6 VDC corresponds to a normal microprocessor environment.

With a diameter of 11 mm, the Series 4 LD is the smallest of four versions. Larger models measuring 15 mm, 17 mm and 19 mm in diameter are also available for relative pressure measurements.