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參數資料
| 型號： | ADT7481ARMZ-1RL |
| 廠商： | ON Semiconductor |
| 文件頁數： | 18/20頁 |
| 文件大小： | 237K |
| 描述： | IC SENSOR TEMP 2CH ALARM 10MSOP |
| 產品變化通告： | MFG CHG Notification ADI to ON Semi |
| 標準包裝： | 3,000 |
| 功能： | 溫度監控系統（傳感器） |
| 傳感器類型： | 內部和外部 |
| 感應溫度： | -40°C ~ 120°C，外部傳感器 |
| 精確度： | ±2.5°C（最小值） |
| 拓撲： | ADC，比較器，多路復用器，寄存器庫 |
| 輸出類型： | SMBus? |
| 輸出警報： | 是 |
| 輸出風扇： | 是 |
| 電源電壓： | 3 V ~ 3.6 V |
| 工作溫度： | -40°C ~ 120°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 10-TFSOP，10-MSOP（0.118"，3.00mm 寬） |
| 供應商設備封裝： | 10-MSOP |
| 包裝： | 帶卷 (TR) |
| 其它名稱： | ADT7481ARMZ-1REEL ADT7481ARMZ-1REEL-ND |
ADT7481
http://onsemi.com
18
causes a lag in the response of the sensor to a temperature
change.
In the case of the remote sensor, this should not be a
problem, since it will either be a substrate transistor in the
processor or a small package device, such as an SOT23,
placed in close proximity to it.
The on-chip sensor, however, will often be remote from
the processor and only monitors the general ambient
temperature around the package. In practice, the ADT7481
package will be in electrical, and hence, thermal contact with
a PCB and may also be in a forced airflow. How accurately
the temperature of the board and/or the forced airflow
reflects the temperature to be measured will also affect the
accuracy of the measurement. Self-heating, due to the power
dissipated in the ADT7481 or the remote sensor, causes the
chip temperature of the device (or remote sensor) to rise
above ambient. However, the current forced through the
remote sensor is so small that self-heating is negligible. The
worst-case condition occurs when the ADT7481 is
converting at 64 conversions per second while sinking the
maximum current of 1 mA at the ALERT
and THERM
output. In this case, the total power dissipation in the device
is about 4.5 mW. The thermal resistance, q
JA
, of the
MSOP10 package is about 142癈/W.
Layout Considerations
Digital boards can be electrically noisy environments, and
the ADT7481 measures very small voltages from the remote
sensor, so care must be taken to minimize noise induced at
the sensor inputs. Take the following precautions:
1. Place the ADT7481 as close as possible to the
remote sensing diode. Provided that the worst
noise sources such as clock generators,
data/address buses, and CRTs are avoided, this
distance can range from 4 to 8 inches.
2. Route the D+ and D tracks close together, in
parallel, with grounded guard tracks on each side.
To minimize inductance and reduce noise pick up,
a 5 mil track width and spacing is recommended.
Provide a ground plane under the tracks if
possible.
Figure 21. Typical Arrangement of Signal Tracks
5 MIL
5 MIL
5 MIL
5 MIL
5 MIL
5 MIL
5 MIL
GND
D
D+
GND
3. Try to minimize the number of copper/solder
joints that can cause thermocouple effects. Where
copper/solder joints are used, make sure that they
are in both the D+ and D path and at the same
temperature.
Thermocouple effects should not be a major
problem as 1癈 corresponds to about 200 mV, and
thermocouple voltages are about 3 mV/癈 of
temperature difference.
Unless there are two thermocouples with a large
temperature differential between them,
thermocouple voltages should be much less than
200 mV.
4. Place a 0.1 mF bypass capacitor close to the V
DD
pin. In extremely noisy environments, an input
filter capacitor may be placed across D+ and D
close to the ADT7481. This capacitance can affect
the temperature measurement, so care must be
taken to ensure that any capacitance seen at D+
and D is a maximum of 1,000 pF. This maximum
value includes the filter capacitance, plus any
cable or stray capacitance between the pins and the
sensor diode.
5. If the distance to the remote sensor is more than 8
inches, the use of twisted pair cable is
recommended. A total of 6 feet to 12 feet of cable
is needed.
For really long distances (up to 100 feet), use
shielded twisted pair, such as Belden No. 8451
microphone cable. Connect the twisted pair to D+
and D and the shield to GND close to the
ADT7481. Leave the remote end of the shield
unconnected to avoid ground loops.
Because the measurement technique uses switched
current sources, excessive cable or filter capacitance can
affect the measurement. When using long cables, the filter
capacitance can be reduced or removed.
Application Circuit
Figure 22 shows a typical application circuit for the
ADT7481, using discrete sensor transistors. The pullups on
SCLK, SDATA, and ALERT
are required only if they are not
already provided elsewhere in the system.
The SCLK and SDATA pins of the ADT7481 can be
interfaced directly to the SMBus of an I/O controller, such
as the Intel
?/DIV>
820 chipset.
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相關代理商/技術參數 |
參數描述 |
|---|---|
| ADT7481ARMZ-R7 | 功能描述:板上安裝溫度傳感器 2 CH TEMP SNSR/ALARM 2 WIRE SMBUS INTRFCE RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數字輸出 - 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 關閉: 安裝風格: 封裝 / 箱體: 設備功能:Temperature and Humidity Sensor |
| ADT7481ARMZ-REEL | 功能描述:板上安裝溫度傳感器 2 CH TEMP SNSR/ALARM 2 WIRE SMBUS INTRFCE RoHS:否 制造商:Omron Electronics 輸出類型:Digital 配置: 準確性:+/- 1.5 C, +/- 3 C 溫度閾值: 數字輸出 - 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 關閉: 安裝風格: 封裝 / 箱體: 設備功能:Temperature and Humidity Sensor |
| ADT7481ARMZ-REEL7 | 功能描述:IC SENSOR TEMP 2CH ALARM 10MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 熱管理 系列:- 標準包裝:1 系列:- 功能:溫度監控系統（傳感器） 傳感器類型:內部和外部 感應溫度:-40°C ~ 125°C，外部傳感器 精確度:±2.5°C 本地（最大值），±5°C 遠程（最大值） 拓撲:ADC，比較器，寄存器庫 輸出類型:2 線 SMBus? 輸出警報:無 輸出風扇:無 電源電壓:2.7 V ~ 5.5 V 工作溫度:-40°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:SOT-23-8 供應商設備封裝:SOT-23-8 包裝:Digi-Reel® 其它名稱:296-22675-6 |
| ADT7481EBZEVB | 功能描述:EVALUATION BOARD ADT7481 制造商:on semiconductor 系列:* 零件狀態:在售 標準包裝:1 |
| ADT7482 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Dual Channel Temperature Sensor and Overtemperature Alarm |
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