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Fast temp sensors tout speed+stability

Melville, New York — ZMD America and Innovative Sensor Technology (IST) AG claimed a breakthrough in high-precision temperature sensor ICs with their highly accurate TSic family.

“By utilizing IST's capabilities to calibrate high-precision sensors, these devices offer companies an accuracy rating that we believe is a factor of five above devices currently in the market today,” said Thilo von Selchow, ZMD's CEO.

There are five new products available: TSic 106 (±0.5°C accuracy at room temperature), TSic 206 (±0.5°C accuracy from +10°C to 90°C), TSic 306 (±0.3°C accuracy from +10°C to 90°C), the TSic 506F (±0.1°C accuracy from +5°C to 45°C, and -0.1, +0.2°C) and the TSic 706VHA (±0.05°C accuracy from +35°C up to 45°C).

Critical issues for achieving these breakthrough specifications were the selection of the appropriate semiconductor technology, analog design, the robustness and simplicity to read the digital signal transducer, and ZACwire data transfer, von Selchow said. “The digital sequential data transfer offers a compelling solution with minimal development effort,” he added.

The TSic sensor family features low-power consumption of 45μA and a supply voltage of 2.97 V to 5.5 V. The sensors have a self-heating temperature of less than 0.07°C for mobile devices, high-precision conventional measurement systems, products requiring fast temperature control, and applications requiring wireless digital signal transmission.

The sensors are available now in SOP-8 (SOIC-8) and an e-line (TO-92-compliant) packages. Measuring 1.6mm x 1.5mm, the calibrated sensores are practical for chip-on-board, chip-on-flex, and chip-scale packages. Other customer-specific packaging, output configurations or temperature calibration ranges are available for high-volume applications as well.

 
 
See related block diagram

Pricing depends on accuracy and starts at $1.14 for the SOP-8 style (±1°C) and $2.28 for the SOP-8 (±0.3°C) in 500-piece quantities.
Click here for the temp sensor data sheets.

ZMD America , 1-631-549-2666, www.ZMDA.com.

IST AG Switzerland , +41-71-987-7373, www.IST-AG.com.

The TSic temperature sensor family is said to be fully tested and calibrated — with absolute measurement accuracy on delivery — no further calibration needed.

The new family combines outstanding accuracy with long term stability, yet it is very simple to use, said Frank Cooper, president of ZMD America.

The sensors employ a high-precision bandgap reference with a proportional-to-absolute temperature (PTAT) output; a low-power, precision analog-to-digital converter (A/D converter); and an on-chip DSP core with E2PROM to precisely calibrate the output temperature signal.

A joint venture between ZMD America and IST AG (Wattwil, Switzerland) resulted in the development of this temperature sensor family with a rapid response time. Comparable products with accuracy of less than ±0.5 would cost a lot more and possess a significantly higher maximum supply current, Cooper said.

The response time of the TSic family is extremely fast (63 percent of a temperature step is reached after 0.8 seconds in an SOP-8 and/or e-line package, and can be made accurately in less than three seconds when measured in water), Cooper said. The chip on flex (COF) package is even faster, he said. “In customer-specific product versions, the TSic COF device can provide a new measurement every 4 ms. This is a key feature for improved accuracy and performance over other devices,” Cooper said.

Alternatives to digital IC-based temperature sensors include passive sensors like negative temperature coefficient (NTC) thermistors and analog ICs, which lack precision, require additional components, and have an analog signal that is noise sensitive and requires a costly A/D converter, Cooper said.

Although platinum sensors like resistance temperature detectors (RTDs) are very precise, they also require additional components, require more power and have noise issues, he said.

This is ZMD's first standalone temperature sensor. Previously, they did make temp sensors for their ASIC products. ZMD provided the high precision bandgap reference with PTAT output, as well as the ZACwire interface, which offers many advantages for sensor interfacing, Cooper said. “ZACwire is very simple for device interfacing and only needs one input per attached sensor at the microcontroller level,” he said.

Prior to the joint venture, IST AG produced platinum- and nickel-based temperature sensors. The TSic family represents IST AG's first IC-based temperature sensor. The company is banking on its 14 years experience calibrating millions of highly accurate platinum sensors, which it applied to the TSic family, Cooper said.

Previous-generation products from other vendors also offer temperature sensors in the -50°C to +150°C temperature range. In comparison with 20 similar products over the same temperature range, however, competing sensors have a resolution starting at ± 0.5°C to ± 3°C, whereas the TSic product family provides accuracy of 0.1°C, 0.3°C or 0.5°C, Cooper said.

Another key feature of these devices is low power consumption, which reduces self heating and is necessary for wireless or battery driven applications. If a temp sensor has high self heating such as 0.3°C or more, which is very typical today, this will limit high accuracy measurement. “Self heating is different in different environmental conditions and therefore can not be compensated at the calibration level,” Cooper said.

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