參數(shù)資料
型號(hào)： DS18B20P
廠商： DALLAS SEMICONDUCTOR
元件分類： Switch/Digital Output Temperature Sensor
英文描述： DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 0.50Cel, RECTANGULAR, SURFACE MOUNT
封裝： TSOC-6
文件頁(yè)數(shù)： 20/26頁(yè)
文件大?。?/td> 387K
代理商： DS18B20P
DS18B20
3 of 26
DS18B20 BLOCK DIAGRAM Figure 1
PARASITE POWER
The block diagram (Figure 1) shows the parasite-powered circuitry. This circuitry “steals” power
whenever the DQ or VDD pins are high. DQ will provide sufficient power as long as the specified timing
and voltage requirements are met (see the section titled “1-Wire Bus System”).
The advantages of
parasite power are twofold: 1) by parasiting off this pin, no local power source is needed for remote
sensing of temperature, and 2) the ROM may be read in absence of normal power.
In order for the DS18B20 to be able to perform accurate temperature conversions, sufficient power must
be provided over the DQ line when a temperature conversion is taking place. Since the operating current
of the DS18B20 is up to 1.5 mA, the DQ line will not have sufficient drive due to the 5k pullup resistor.
This problem is particularly acute if several DS18B20s are on the same DQ and attempting to convert
simultaneously.
There are two ways to assure that the DS18B20 has sufficient supply current during its active conversion
cycle. The first is to provide a strong pullup on the DQ line whenever temperature conversions or copies
to the E
2 memory are taking place. This may be accomplished by using a MOSFET to pull the DQ line
directly to the power supply as shown in Figure 2. The DQ line must be switched over to the strong pull-
up within 10
s maximum after issuing any protocol that involves copying to the E2 memory or initiates
temperature conversions. When using the parasite power mode, the VDD pin must be tied to ground.
Another method of supplying current to the DS18B20 is through the use of an external power supply tied
to the VDD pin, as shown in Figure 3. The advantage to this is that the strong pullup is not required on the
DQ line, and the bus master need not be tied up holding that line high during temperature conversions.
This allows other data traffic on the 1-Wire bus during the conversion time. In addition, any number of
DS18B20s may be placed on the 1-Wire bus, and if they all use external power, they may all
simultaneously perform temperature conversions by issuing the Skip ROM command and then issuing the
Convert T command. Note that as long as the external power supply is active, the GND pin may not be
floating.
The use of parasite power is not recommended above 100
°C, since it may not be able to sustain
communications given the higher leakage currents the DS18B20 exhibits at these temperatures. For
64-BIT ROM
AND
1-WIRE PORT
MEMORY AND
CONTROL LOGIC
SCRATCHPAD
8-BIT CRC
GENERATOR
TEMPERATURE SENSOR
HIGH TEMPERATURE
TRIGGER, TH
LOW TEMPERATURE
TRIGGER, TL
CONFIGURATION
REGISTER
POWER
SUPPLY
SENSE
INTERNAL VDD
DQ
VDD
相關(guān)PDF資料
PDF描述
DS18B20X DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 2Cel, RECTANGULAR, SURFACE MOUNT
DS18B20Z DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 0.50Cel, RECTANGULAR, SURFACE MOUNT
DS18B20 DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 0.50Cel, RECTANGULAR, THROUGH HOLE MOUNT
DS18B20U+T&R DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 0.50Cel, SQUARE, SURFACE MOUNT
DS18B20-SL+T&R DIGITAL TEMP SENSOR-SERIAL, 12BIT(s), 0.50Cel, RECTANGULAR, THROUGH HOLE MOUNT
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
DS18B20-PAR 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor
DS18B20-PAR/T&R 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor
DS18B20-PAR_07 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:1-Wire Parasite-Power Digital Thermometer
DS18B20-PAR+T&R 制造商:Maxim Integrated Products 功能描述: 制造商:Maxim Integrated Products 功能描述:TEMP SENSOR DGTL 1-WIRE 3PIN TO-92 - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC THERM MICROLAN PROG-RES TO-92 制造商:Maxim Integrated Products 功能描述:Board Mount Temperature Sensors Prgmble Resolution 1-Wire Parasite Pwr
DS18B20-PAR+T&R 功能描述:板上安裝溫度傳感器 Prgmble Resolution 1-Wire Parasite Pwr RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準(zhǔn)確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數(shù)字輸出 - 總線接口:2-Wire, I2C, SMBus 電源電壓-最大:5.5 V 電源電壓-最小:4.5 V 最大工作溫度:+ 50 C 最小工作溫度:0 C 關(guān)閉: 安裝風(fēng)格: 封裝 / 箱體: 設(shè)備功能:Temperature and Humidity Sensor
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