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參數(shù)資料
| 型號(hào)： | DS18B20Z/T&R |
| 廠商： | Maxim Integrated |
| 文件頁(yè)數(shù)： | 5/22頁(yè) |
| 文件大小： | 528K |
| 描述： | IC THERM MICROLAN PROG-RES 8SOIC |
| 產(chǎn)品培訓(xùn)模塊： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 標(biāo)準(zhǔn)包裝： | 2,500 |
| 功能： | 溫度計(jì)，恒溫計(jì) |
| 傳感器類(lèi)型： | 內(nèi)部 |
| 感應(yīng)溫度： | -55°C ~ 125°C |
| 精確度： | ±2°C（最小值） |
| 拓?fù)洌?/td> | 寄存器庫(kù)，變簽式暫存器 |
| 輸出類(lèi)型： | 1-Wire? |
| 輸出警報(bào)： | 是 |
| 輸出風(fēng)扇： | 無(wú) |
| 電源電壓： | 3 V ~ 5.5 V |
| 工作溫度： | -55°C ~ 125°C |
| 安裝類(lèi)型： | 表面貼裝 |
| 封裝/外殼： | 8-SOIC（0.154"，3.90mm 寬） |
| 供應(yīng)商設(shè)備封裝： | 8-SOIC |
| 包裝： | 帶卷 (TR) |
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DS18B20
5 of 22
The master device can check the alarm flag status of all DS18B20s on the bus by issuing an Alarm Search
[ECh] command. Any DS18B20s with a set alarm flag will respond to the command, so the master can
determine exactly which DS18B20s have experienced an alarm condition. If an alarm condition exists
and the T
H
or T
L
settings have changed, another temperature conversion should be done to validate the
alarm condition.
POWERING THE DS18B20
The DS18B20 can be powered by an external supply on the V
DD
pin, or it can operate in parasite power
mode, which allows the DS18B20 to function without a local external supply. Parasite power is very
useful for applications that require remote temperature sensing or that are very space constrained.
Figure 1 shows the DS18B20s 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 DS18B20 while the bus is high,
and some of the charge is stored on the parasite power capacitor (C
PP
) to provide power when the bus is
low. When the DS18B20 is used in parasite power mode, the V
DD
pin must be connected to ground.
In parasite power mode, the 1-Wire bus and C
PP
can provide sufficient current to the DS18B20 for most
operations as long as the specified timing and voltage requirements are met (see the DC Electrical
Characteristics and AC Electrical Characteristics). However, when the DS18B20 is performing
temperature conversions or copying data from the scratchpad memory to EEPROM, the operating current
can be as high as 1.5mA. This current can cause an unacceptable voltage drop across the weak 1-Wire
pullup resistor and is more current than can be supplied by C
PP
. To assure that the DS18B20 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 4. The 1-Wire
bus must be switched to the strong pullup within 10祍 (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
(t
CONV
) or data transfer (t
WR
= 10ms). No other activity can take place on the 1-Wire bus while the pullup
is enabled.
The DS18B20 can also be powered by the conventional method of connecting an external power supply
to the V
DD
pin, as shown in Figure 5. The advantage of this method is that the MOSFET pullup is not
required, and the 1-Wire bus is free to carry other traffic during the temperature conversion time.
The use of parasite power is not recommended for temperatures above +100癈 since the DS18B20 may
not be able to sustain communications due to the higher leakage currents that can exist at these
temperatures. For applications in which such temperatures are likely, it is strongly recommended that the
DS18B20 be powered by an external power supply.
In some situations the bus master may not know whether the DS18B20s on the bus are parasite powered
or powered by external supplies. The master needs this information to determine if the strong bus pullup
should be used during temperature conversions. To get this information, the master can issue a Skip ROM
[CCh] command followed by a Read Power Supply [B4h] command followed by a read time slot .
During the read time slot, parasite powered DS18B20s will pull the bus low, and externally powered
DS18B20s will let the bus remain high. If the bus is pulled low, the master knows that it must supply the
strong pullup on the 1-Wire bus during temperature conversions.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS18B20Z-W | 制造商:Maxim Integrated Products 功能描述: |
| DS18S20 | 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類(lèi)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/T&R | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:IC THERM MICROLAN HI PREC TO-92 |
| DS18S20/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(lèi)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+ | 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(lèi)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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