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參數(shù)資料
| 型號： | DS18B20Z |
| 元件分類： | 溫度傳感器 |
| 英文描述： | Programmable Resolution 1-Wire Digital Thermometer |
| 中文描述： | 可編程的1 - Wire數(shù)字溫度計 |
| 文件頁數(shù)： | 3/27頁 |
| 文件大?。?/td> | 391K |
| 代理商： | DS18B20Z |
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DS18B20
3 of 27
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 V
DD
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
μ
s maximum after issuing any protocol that involves copying to the E
2
memory or initiates
temperature conversions. When using the parasite power mode, the V
DD
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 V
DD
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
applications in which such temperatures are likely, it is strongly recommended that V
DD
be applied to the
DS18B20.
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 V
DD
DQ
V
DD
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS18B20Z/T&R | 制造商:Maxim Integrated Products 功能描述:HI RES MICROLAN DIG THERM 8-SOIC TR - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC THERM MICROLAN PROG-RES 8SOIC 制造商:Maxim Integrated Products 功能描述:Board Mount Temperature Sensors Prgmble Resolution 1-Wire Parasite Pwr |
| DS18B20Z/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 |
| DS18B20Z+ | 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 |
| DS18B20Z+ | 制造商:Maxim Integrated Products 功能描述:SEMICONDUCTOR ((NW)) |
| DS18B20Z+T&R | 制造商:Maxim Integrated Products 功能描述:HI RES MICROLAN DIG THERM 8-SOIC TR 制造商:Maxim Integrated Products 功能描述:TEMP SENSOR DGTL SERL (1-WIRE) 8SOIC N - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC THERM MICROLAN PROG-RES 8SOIC 制造商:Maxim Integrated Products 功能描述:Board Mount Temperature Sensors Prgmble Resolution 1-Wire Parasite Pwr |
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