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參數(shù)資料
| 型號： | DS18S20-PAR/T&R |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | Switch/Digital Output Temperature Sensor |
| 英文描述： | DIGITAL TEMP SENSOR-SERIAL, 9BIT(s), 0.50Cel, ROUND, THROUGH HOLE MOUNT |
| 封裝： | TO-92, 3 PIN |
| 文件頁數(shù)： | 14/20頁 |
| 文件大?。?/td> | 250K |
| 代理商： | DS18S20-PAR/T&R |
DS18S20-PAR
3 of 20
PARASITE POWER
The DS18S20-PAR’s parasite power circuit allows the DS18S20-PAR to operate without a local external
power supply. This ability is especially useful for applications that require remote temperature sensing or
that are very space constrained. Figure 1 shows the DS18S20-PAR’s parasite-power control circuitry,
which “steals” power from the 1-Wire bus via the DQ pin when the bus is high. The stolen charge
powers the DS18S20-PAR while the bus is high, and some of the charge is stored on the parasite power
capacitor (CPP) to provide power when the bus is low.
The 1-Wire bus and CPP can provide sufficient parasite power to the DS18S20-PAR for most operations
as long as the specified timing and voltage requirements are met (refer to the DC ELECTRICAL
CHARACTERISTICS and the AC ELECTRICAL CHARACTERISTICS sections of this data sheet).
However, when the DS18S20-PAR is performing temperature conversions or copying data from the
scratchpad memory to EEPROM, the operating current can be as high as 1.5 mA. This current can cause
an unacceptable voltage drop across the weak 1-Wire pullup resistor and is more current than can be
supplied by CPP. To assure that the DS18S20-PAR has sufficient supply current, it is necessary to
provide a strong pullup on the 1-Wire bus whenever temperature conversions are taking place or data is
being copied from the scratchpad to EEPROM. This can be accomplished by using a MOSFET to pull
the bus directly to the rail as shown in Figure 2. The 1-Wire bus must be switched to the strong pullup
within 10
ms (max) after a Convert T [44h] or Copy Scratchpad [48h] command is issued, and the bus
must be held high by the pullup for the duration of the conversion (tconv) or data transfer (twr = 10 ms).
No other activity can take place on the 1-Wire bus while the pullup is enabled.
SUPPLYING THE DS18S20-PAR DURING TEMPERATURE CONVERSIONS
Figure 2
OPERATION – MEASURING TEMPERATURE
The core functionality of the DS18S20-PAR is its direct-to-digital temperature sensor. The temperature
sensor output has 9-bit resolution, which corresponds to 0.5
°C steps. The DS18S20-PAR powers-up in a
low-power idle state; to initiate a temperature measurement and A-to-D conversion, the master must issue
a Convert T [44h] command. Following the conversion, the resulting thermal data is stored in the 2-byte
temperature register in the scratchpad memory and the DS18S20-PAR returns to its idle state. The
DS18S20-PAR output data is calibrated in degrees centigrade; for Fahrenheit applications, a lookup table
or conversion routine must be used. The temperature data is stored as a 16-bit sign-extended two’s
complement number in the temperature register (see Figure 3). The sign bits (S) indicate if the
temperature is positive or negative: for positive numbers S = 0 and for negative numbers S = 1. Table 2
gives examples of digital output data and the corresponding temperature reading.
Resolutions greater than 9 bits can be calculated using the data from the temperature, COUNT REMAIN
and COUNT PER °C registers in the scratchpad. Note that the COUNT PER °C register is hard-wired to
VPU
4.7K
1-Wire Bus
Micro-
processor
DS18S20-PAR
GND
DQ
To Other
1-Wire Devices
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| DS18S20-PAR | DIGITAL TEMP SENSOR-SERIAL, 9BIT(s), 0.50Cel, ROUND, THROUGH HOLE MOUNT |
| DS18S20Z | DIGITAL TEMP SENSOR-SERIAL, 9BIT(s), 0.50Cel, RECTANGULAR, SURFACE MOUNT |
| DS18S20 | DIGITAL TEMP SENSOR-SERIAL, 9BIT(s), 0.50Cel, RECTANGULAR, THROUGH HOLE MOUNT |
| DS18S20-SL+T&R | DIGITAL TEMP SENSOR-SERIAL, 9BIT(s), 0.50Cel, RECTANGULAR, THROUGH HOLE MOUNT |
| DS18S20Z/T&R | DIGITAL TEMP SENSOR-SERIAL, 9BIT(s), 0.50Cel, RECTANGULAR, SURFACE MOUNT |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS18S20-SL/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 |
| DS18S20-SL+T&R | 制造商:Maxim Integrated Products 功能描述:TEMP SENSOR DGTL 1-WIRE - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC THERM MICROLAN HI-PREC TO-92 制造商:Maxim Integrated Products 功能描述:Board Mount Temperature Sensors Prgmble Resolution 1-Wire Parasite Pwr |
| DS18S20-SL+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 |
| DS18S20-W | 制造商:Maxim Integrated Products 功能描述: |
| DS18S20Z | 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 |
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