How to simplify IC temperature sensor design

Temperature sensors have now undergone great changes. To date, all temperature sensors available on the market do not have analog/digital output functions. The use of thermistors, RTDs, and thermocouples is accompanied by the use of an analog conversion device or a silicon temperature sensor. Unfortunately, in important applications, these analog output devices require a comparator, an ADC, or an amplifier to convert their analog signals into useful signals. Thus, when the integration capability reaches a higher level, a temperature sensor with a digital interface can appear. There are a wide variety of Ics temperature sensors sold today, ranging from simple devices that handle transboundary temperature signals to remote temperature remote control and measurements, and can be programmed with temperature settings. The current choice is not only the selection of the analog output or digital output sensor, but also a wider choice of sensor models. These choices should be matched to your system.

The "analog pulse" sensor can have various forms of digital output. The voltage VVOUT vs. temperature curve is determined by the IC. When a particular threshold temperature occurs, the digital output changes. In this case, "pulse" is added to the analog temperature sensor without the comparator and reference voltage. After the device is gated, other types of “pulse” components transmit temperature data in the form of delay times, which may also be in frequency or square wave form. System monitoring is the most complex of the four types. Used in conjunction with digital I/O ports, these devices are typically used to sense system voltage and provide an alarm signal when the voltage rises or falls to a certain I/O setting. This type of IC is sometimes used for fan detection or control. In some cases, this device is used to determine if the fan is working properly. More complex models can be used to control one or more temperature measurement points of the fan.

Both thermistors and silicon temperature sensors are widely used as analog output temperature sensors. Silicon temperature sensors have much better linearity than thermistors. However, thermistors also provide reasonable linearity and good sensitivity over a narrow temperature range. Many of the earlier circuits built with thermistors are now outdated and have now been replaced with silicon temperature sensors. The silicon temperature sensor can use different scale output formats. For example, it can be expressed in K, 0C and 0F on the output conversion. In most applications, the outputs of these devices are fed into comparators or A/D converters to convert temperature data into digital format. Although this is an additional requirement of the device, the thermistors and silicon temperature sensors due to their price Cheap and can be applied for many years.

About five years ago, a new type of temperature sensor was introduced. These devices include digital interfaces (allowing communication with the microcontroller). This communication interface typically includes I2C and SMBus serial buses, while other serial communication interfaces such as SPI are also common. The interface can transmit digital data to the microprocessor, which can also accept commands from the microcontroller. These instructions are often temperature domain values. If the temperature exceeds the limit, a digital signal is generated on the temperature sensor IC and it will generate an interrupt to the microcontroller. The microcontroller can then adjust the fan speed or adjust the microprocessor so that the temperature is under control. This type of device is widely used and remote temperature measurement can be performed in these applications. For remote measurement, most high-performance CPUs include an onchip converter that provides an analog voltage value for the temperature. Another important feature of this type of sensor is the ability to interrupt the microprocessor when the measured temperature is not within the range between the high limit and the low limit. In other sensors, an interrupt signal should be generated when the measured temperature value is too high or low (no two values ​​at the same time).

IC sensors can provide a combination of various functional interfaces. Because these devices are constantly improving, system installers will see more application effects - new features and new methods of sensors displaying special interfaces in the system. Ultimately, the design level of the chip will reach more electronic components integrated on one chip to ensure that the temperature sensor can contain more new functions and a more special interface.