The integrated temperature sensor is fabricated using a silicon semiconductor integrated process, so it is also known as a silicon sensor or a monolithic integrated temperature sensor. It is a commonly used temperature sensor product, which has the advantages of good linearity, moderate precision, high sensitivity, small size and convenient use. It can effectively compensate for the slow response time, large thermal inertia and poor internal linearity of traditional temperature sensors. It is widely used in many fields.
Principle and classification of integrated temperature sensor
According to the mode of the temperature sensor output signal, it can be roughly divided into three categories: digital temperature sensor, logic output temperature sensor, and analog temperature sensor.
- The analog integrated temperature sensor was introduced in the 1980s. It is a dedicated IC that integrates a temperature sensor on a single chip to perform temperature measurement and analog signal output functions. The main features of the analog integrated temperature sensor are single function (measuring temperature only), small temperature measurement error, low price, fast response speed, long transmission distance, small size, micro power consumption, etc. It is suitable for long-distance temperature measurement and control measurement. Non-linear calibration is required and the peripheral circuitry is simple. It is an integrated sensor that is most commonly used at home and abroad. Typical products include AD590, AD592, TMP17, and LM135.
Analog integrated temperature controllers mainly include temperature-controlled switches and programmable temperature controllers. Typical products are LM56, AD22105 and MAX6509. Some enhanced integrated temperature controllers (such as the TC652/653) also include A/D converters and cured programs, which have some similarities to smart temperature sensors. But it is a self-contained system, and it is not controlled by the microprocessor when it is working. This is the main difference between the two.
- Intelligent temperature sensors (also known as digital temperature sensors) were introduced in the mid-1990s. It is the result of microelectronics, computer technology and automated test technology (ATE). At present, a variety of intelligent temperature sensor products have been developed internationally. The smart temperature sensor internally contains a temperature sensor, an A/D converter, a signal processor, a memory (or register), and an interface circuit. Some products also come with multiplexers, central controllers (CPUs), random access memory (RAM), and read-only memory (ROM). The intelligent temperature sensor is characterized by the ability to output temperature data and associated temperature control, adapting to various microcontrollers (MCU); and it is based on hardware to implement test functions through software, and its intelligent harmony also depends on At the level of software development.
3, logic output type temperature sensor In many applications, we do not need to strictly measure the temperature value, only concerned about whether the temperature exceeds a set range, once the temperature exceeds the specified range, it will send an alarm signal to start or turn off the fan, Air conditioning, heaters or other control equipment, a logic output temperature sensor is available at this time. The LM56, MAX6501-MAX6504, and MAX6509/6510 are typical representatives. The LM56 is a high-precision low-voltage temperature switch manufactured by NS, with a built-in 1.25V reference voltage output. The maximum load is only 50ìA. The MAX6501/02/03/04 is a temperature monitor switch with logic output and SOT-23 package. Its design is very simple: the user chooses a temperature threshold that is close to the control he needs (preset by the factory at -45) °C to +115 ° C, the preset interval is 10 ° C). It can be used directly into the circuit without any external components.
Typical application of integrated temperature sensor
1, logic output type temperature sensor: mainly used in LM56, MAX6501-MAX6504, MAX6509/6510. When in use, the temperature range is set. When the temperature exceeds the specified range, an alarm signal is issued to activate or deactivate the fan, air conditioner, heater or other control device. In this case, a logic output temperature sensor can be selected.
- Digital temperature sensor: If a digital interface temperature sensor is used, this type of device can transmit temperature data through a single line and a microprocessor, providing three flexible output methods – frequency, period or timing, which output The square wave signal has a period proportional to the absolute temperature. The device is connected to the microprocessor through an I/O, and the temperature can be calculated by measuring the period using a counter inside the microprocessor.