产品类别
产品标签
铠装热电偶传感器
刀片保险丝座
汽车插片保险丝
汽车保险丝
陶瓷管保险丝
断路器
盘式温控器
DS18b20 温度传感器
电气保险丝
快熔断/慢熔断保险丝
保险丝盒支架
玻璃管保险丝
直插式保险丝座
限位卡盘温控器
迷你断路器
电机过载保护器
电机热保护
NTC传感器
NTC热敏电阻传感器
PCB 安装保险丝座
PPTC自恢复保险丝
PT100温度传感器
正温度系数热敏电阻
传感器连接器线束
传感器探头 & 电缆
慢熔断微型保险丝
表面贴装保险丝
临时截止链接
温控开关
温度保险丝
温度感应器
温度传感器电缆
温度传感器探头
温度开关
热切断
热切断开关
热熔断器
热保护器
热敏开关
热敏电阻传感器探头
DS18b20 传感器探头和电缆
DS18B20温度传感器特点: 防水的, 防腐.
包装细节: 可根据需要定制. MAXIM原装进口; TO-92封装; 大量库存. 并提供不锈钢管防水封装的DS18B20数字温度传感器.
分类: 温度感应器
标签: DS18b20 温度传感器, 温度感应器, 温度传感器电缆
The ds18b20 temperature sensor probe has high accuracy. The temperature measurement accuracy can reach 0.01℃, and the temperature measurement accuracy in the wide temperature range is 0.1℃. Good stability and high precision in mass production.
The DS18B20 digital sensor probe and cable are easy to connect and can be used in a variety of situations after being packaged. Such as stainless steel straight pipe type, 螺纹型, magnet adsorption type, various models, including LTM8877, LTM8874 and so on.
DS18B20 is a commonly used digital temperature sensor. It outputs a digital signal and has the characteristics of small size, low hardware overhead, strong anti-interference ability and high accuracy. Its appearance mainly changes depending on the application. The encapsulated DS18B20 can be used for cable temperature measurement, blast furnace water circulation temperature measurement, boiler temperature measurement, machine room temperature measurement, agricultural greenhouse temperature measurement, clean room temperature measurement, ammunition depot temperature measurement and other non-limit temperature occasions. Wear-resistant and impact-resistant, small in size, 便于使用, with various packaging forms, it is suitable for digital temperature measurement and control of various small space equipment.
Main features of DS18B20 sensor probe
1. Main features of DS18B20
1.1. The adaptable voltage range is wider, voltage range: 3.0~5.5V, and can be powered by the data line in parasitic power mode
1.2. Unique single-wire interface method. When DS18B20 is connected to the microprocessor, it only needs one port line to achieve two-way communication between the microprocessor and DS18B20.
1.3. DS18B20 supports multi-point networking function. Multiple DS18B20 can be connected in parallel on the only three lines to achieve multi-point temperature measurement.
1.4. DS18B20 does not require any external components during use. All sensing components and conversion circuits are integrated into an integrated circuit shaped like a triode.
1.5. Temperature range -55℃~+125℃, accuracy is ±0.5℃ at -10~+85℃
1.6. The programmable resolution is 9~12 bits, and the corresponding resolvable temperatures are 0.5℃, 0.25℃, 0.125℃ and 0.0625℃ respectively, which can achieve high-precision temperature measurement.
1.7. At 9-bit resolution, the temperature can be converted into numbers in up to 93.75ms. At 12-bit resolution, the temperature value can be converted into numbers in up to 750ms, which is faster.
1.8. The measurement results directly output digital temperature signals and are serially transmitted to the CPU via the "one-line bus". 同时, the CRC check code can be transmitted, which has strong anti-interference and error correction capabilities.
1.9. Negative voltage characteristics: When the polarity of the power supply is reversed, the chip will not be burned due to heat, but it will not work properly.
2. Appearance and internal structure of DS18B20 sensor
The internal structure of the DS18B20 sensor mainly consists of four parts: 64-bit photolithography ROM, 温度传感器, non-volatile temperature alarm triggers TH and TL, and configuration register.
The appearance and pin arrangement of DS18B20 are as follows:
DS18B20 pin definition:
(1) DQ is the digital signal input/output terminal;
(2) GND is the power ground;
(3) VDD is the input terminal of the external power supply (grounded in the parasitic power wiring mode).
3. Working principle of DS18B20
The reading and writing timing and temperature measurement principle of DS18B20 are the same as those of DS1820, except that the number of digits of the temperature value obtained is different due to different resolutions, and the delay time during temperature conversion is reduced from 2s to 750ms. The oscillation rate of high temperature coefficient crystal oscillator changes significantly with temperature changes, and the generated signal is used as the pulse input of counter 2. Counter 1 and the temperature register are preset at a base value corresponding to -55°C. Counter 1 counts down the pulse signal generated by the low temperature coefficient crystal oscillator. When the preset value of counter 1 decreases to 0, the value of the temperature register will be increased by 1, the preset value of counter 1 will be reloaded, and counter 1 will restart counting the pulse signals generated by the low temperature coefficient crystal oscillator. This cycle continues until counter 2 counts to 0, then stops accumulating the temperature register value. 此时, the value in the temperature register is the measured temperature. The slope accumulator in Figure 3 is used to compensate and correct the nonlinearity in the temperature measurement process, and its output is used to correct the preset value of counter 1.
DS18B20 has 4 main data components:
(1) The 64-bit serial number in the photoetched ROM is photoetched before leaving the factory. It can be regarded as the address serial code of the DS18B20. The arrangement of the 64-bit photolithography ROM is: the first 8 bits (28H) are the product type number, and the next 48 bits are the serial number of the DS18B20 itself. The last 8 bits are the cyclic redundancy check code of the previous 56 bits (CRC=X8+X5+X4+1). The function of photolithography ROM is to make each DS18B20 different, so that multiple DS18B20s can be connected to one bus.
(2) The temperature sensor in DS18B20 can complete the measurement of temperature. Take 12-bit conversion as an example: it is provided in the form of 16-bit sign-extended two's complement reading, expressed in the form of 0.0625°C/LSB, where S is the sign bit.
This is the 12-bit data obtained after 12-bit conversion, which is stored in two 8-bit RAMs of 18B20. The first 5 bits in binary are the sign bits. If the measured temperature is greater than 0, these 5 bits are 0. Just multiply the measured value by 0.0625 to get the actual temperature. If the temperature is less than 0, these 5 bits are 1, and the measured value needs to be inverted, plus 1, and then multiplied by 0.0625 to get the actual temperature. 例如, the digital output of +125℃ is 07D0H, the digital output of +25.0625℃ is 0191H, the digital output of -25.0625℃ is FE6FH, and the digital output of -55℃ is FC90H.
(3) DS18B20 temperature sensor memory DS18B20. The internal memory of the temperature sensor includes a high-speed scratchpad RAM and a non-volatile electrically erasable EEPRAM, which stores the high-temperature and low-temperature flip-flops TH, TL and structural registers.
(4) Configuration register The meaning of each bit of this byte is as follows:
Table 3: Configuration register structure
The lower five bits are always "1", and TM is the test mode bit, which is used to set whether the DS18B20 is in working mode or test mode. This bit is set to 0 when DS18B20 leaves the factory, and users should not change it. R1 and R0 are used to set the resolution, as shown in the following table: (DS18B20 is set to 12 bits when shipped from the factory)
Table 4: Temperature resolution setting table
4. High-speed temporary storage memory The high-speed temporary storage memory consists of 9 bytes, and its allocation is shown in Table 5. When the temperature conversion command is issued, the converted temperature value is stored in the 0th and 1st bytes of the cache memory in two-byte complement form. The microcontroller can read this data through the single-wire interface. When reading, the low bit is in front and the high bit is in the back. The data format is shown in Table 1. Corresponding temperature calculation: When the sign bit S=0, directly convert the binary bit to decimal; when S=1, first convert the complement to the original code, and then calculate the decimal value. Table 2 shows some of the corresponding temperature values. The ninth byte is the redundancy check byte.
Table 5: DS18B20 temporary register distribution
According to the communication protocol of DS18B20, the host (single chip microcomputer) must go through three steps to control DS18B20 to complete temperature conversion: DS18B20 must be reset before each read and write. After the reset is successful, a ROM command is sent, and finally a RAM command is sent, so that the predetermined operation can be performed on the DS18B20. Reset requires the main CPU to pull the data line down for 500 microseconds and then release it. When DS18B20 receives the signal, it waits for about 16 to 60 microseconds, and then sends out a low pulse of 60 to 240 microseconds. The main CPU receives this signal to indicate successful reset.
Table 6: ROM instruction list
联系我们
等待您的电子邮件, 我们将在短时间内回复您 12 小时提供您需要的有价值的信息.
相关产品
PT100 RTD sensor Probe & 电缆
PT100 thermal resistance acquisition modules can be connected to the RS-485 local control network through the isolated 485 communication interface. RS-485 allows up to 32 PT100 thermal resistance acquisition modules to be hung on the same bus. 然而, if Link-Max's RS-485 repeater is used, 取决于 256 PT100 thermal resistance acquisition modules can be connected to the same network, and the maximum communication distance is 1200m.
RTD PT100 Temperature Sensor Probe with Cable
What is a Platinum thermal resistance sensor?
An RTD (Resistance Temperature Detector) is a Platinum thermal resistance whose resistance changes with changes in temperature. Its resistance increases as the sensor temperature increases. The relationship between resistance and temperature is well known and repeatable over time. RTD is a passive device. It does not produce output by itself. External electronics can be used to measure the sensor resistance by passing a small current through the sensor to produce a voltage. Typically 1 mA or less measurement current, maximum 5 嘛, without risk of self-heating.
Thermistor temperature sensor for electrical appliances
As everyone knows, the Small appliances , as a popular household kitchenware, not only has the function of heating, but also has many automatic functions. 例如, automatic heat preservation, automatic boiling water, automatic rice cooking, automatic soup cooking and other functions. The realization of all these automatic functions requires the Small appliances to be able to accurately measure and control the temperature. The existing Small appliances mainly uses a temperature sensor for temperature measurement. Such as: