New Trends in the Development of Smart Temperature Sensors

In the 21st century, smart temperature sensors are rapidly advancing into the high-tech field with high precision, diverse functions, standardized buses, high reliability and safety, and the development of virtual and networked sensors. In addition, the development of monolithic temperature measurement systems is at the right time, heralding future technological innovations.

(1) Improvement of temperature measurement accuracy and resolving power

In the mid-1990s, the earliest introduction of intelligent temperature sensors, the use of 8-bit A/D converter, its temperature measurement accuracy is low, the resolution can only reach 1 ℃. At present, foreign countries have introduced a variety of high-precision, high-resolution intelligent temperature sensors, the use of 9 ~ 12-bit A/D converter, resolution generally up to 0.5 ~ 0.0625 ℃. By the U.S. DALLAS Semiconductor Corporation's newly developed DS1624 type of high-resolution intelligent temperature sensors, can output 13-bit binary data, its resolution is as high as 0.03125 ℃, temperature measurement accuracy of ± 0.2 ℃.

In order to improve the conversion rate of multi-channel smart temperature sensor, some chips also use high-speed successive approximation A/D converter. The AD7817 5-channel intelligent temperature sensor, for example, its local sensor, each remote sensor conversion time is only 27μs, 9μs.

(2) Addition of testing functions

New smart temperature sensors are also being enhanced with new test functions. For example, DS1629 type single-wire intelligent temperature sensor increased real-time calendar clock (RTC), so that its function is more complete. DS1624 also increased the storage function, the use of the chip's internal 256 bytes of E2PROM memory, you can store the user's short message. In addition, the intelligent temperature sensor is from a single channel to the direction of multi-channel development, which creates good conditions for the development and development of multi-channel temperature measurement and control system.

Smart temperature sensors have a variety of operating modes to choose from, including single conversion mode, continuous conversion mode, standby mode, and in some cases, low-temperature limit extension mode, which is very easy to operate. For some smart temperature sensors, the host (external microprocessor or microcontroller) can also set the A/D conversion rate (typically MAX6654), resolution and maximum conversion time (typically DS1624) through the corresponding registers.

Intelligent temperature controllers are developed on the basis of intelligent temperature sensors. Intelligent temperature controller adapted to a variety of microcontrollers, constituting an intelligent temperature control system; they can also be separated from the microcontroller to work alone, constituting a temperature controller by itself, typical products are DS1620, DS1623, TCN75, LM76, MAX6625.

(3) Standardization and normalization of bus technology

At present, the intelligent temperature sensor bus technology has also been standardized, standardized, the bus used mainly single-wire (-Wire) bus, I2C bus, SMBUS bus and SPI bus.