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參數(shù)資料
| 型號： | ADT7461ARMZ-2R |
| 廠商： | ON Semiconductor |
| 文件頁數(shù)： | 16/20頁 |
| 文件大小： | 268K |
| 描述： | IC TEMP SENSOR DGTL 2CH 8-MSOP |
| 產(chǎn)品變化通告： | MFG CHG Notification ADI to ON Semi |
| 標(biāo)準(zhǔn)包裝： | 3,000 |
| 功能： | 溫度監(jiān)控系統(tǒng)（傳感器） |
| 傳感器類型： | 內(nèi)部和外部 |
| 感應(yīng)溫度： | 0°C ~ 127°C，-55°C ~ 150°C |
| 精確度： | ±3°C |
| 拓?fù)洌?/td> | ADC，比較器，多路復(fù)用器，寄存器庫 |
| 輸出類型： | 2 線 SMBus? |
| 輸出警報(bào)： | 是 |
| 輸出風(fēng)扇： | 是 |
| 電源電壓： | 3 V ~ 5.5 V |
| 工作溫度： | -40°C ~ 120°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 8-TSSOP，8-MSOP（0.118"，3.00mm 寬） |
| 供應(yīng)商設(shè)備封裝： | Micro8? |
| 包裝： | 帶卷 (TR) |
ADT7461
http://onsemi.com
16
Figure 21. Operation of the THERM
and THERM2
Interrupts
THERM2
LIMIT
905C
805C
705C
605C
505C
405C
TEMPERATURE
1
2
3
4
THERM
305C
THERM
LIMIT
THERM2
1. When the THERM2
limit is exceeded, the
THERM2
signal asserts low.
2. If the temperature continues to increase and
exceeds the THERM
limit, the THERM
output
asserts low.
3. The THERM
output deasserts (goes high) when the
temperature falls to THERM
limit minus hysteresis.
No hysteresis value is shown in Figure 21.
4. As the system continues to cool and the
temperature falls below the THERM2
limit, the
THERM2
signal resets. Again, no hysteresis value
is shown for THERM2
.
Both the external and internal temperature
measurements cause THERM
and THERM2
to
operate as described.
Application Information
Noise Filtering
For temperature sensors operating in noisy environments,
the industry standard practice was to place a capacitor across
the D+ and D pins to help combat the effects of noise.
However, large capacitances affect the accuracy of the
temperature measurement, leading to a recommended
maximum capacitor value of 1,000 pF. While this capacitor
reduces the noise, it does not eliminate it, making it difficult
to use the sensor in a very noisy environment.
The ADT7461 has a major advantage over other devices
for eliminating the effects of noise on the external sensor.
The series resistance cancellation feature allows a filter to be
constructed between the external temperature sensor and the
part. The effect of any filter resistance seen in series with the
remote sensor is automatically cancelled from the
temperature result.
The construction of a filter allows the ADT7461 and the
remote temperature sensor to operate in noisy environments.
Figure 22 shows a low-pass R-C-R filter with the following
values:
R = 100 W and C = 1 nF
This filtering reduces both common-mode noise and
differential noise.
Figure 22. Filter Between Remote Sensor and
ADT7461 Factors Affecting Diode Accuracy
100 W
100 W
1 nF
D+
D
REMOTE
TEMPERATURE
SENSOR
Remote Sensing Diode
The ADT7461 is designed to work with substrate
transistors built into processors or with discrete transistors.
Substrate transistors are generally PNP types with the
collector connected to the substrate. Discrete types can be
either PNP or NPN transistor connected as a diode
(base-shorted to collector). If an NPN transistor is used, the
collector and base are connected to D+ and the emitter to D.
If a PNP transistor is used, the collector and base are
connected to D and the emitter to D+.
To reduce the error due to variations in both substrate and
discrete transistors, several factors should be taken into
consideration:
" The ideality factor, nF, of the transistor is a measure of
the deviation of the thermal diode from ideal behavior.
The ADT7461 is trimmed for an nF value of 1.008. The
following equation may be used to calculate the error
introduced at a temperature T (癈), when using a
transistor whose nF does not equal 1.008. Consult the
processor data sheet for the nF values.
DT + (nF * 1.008)1.008 (273.15 Kelvin ) T) (eq. 1)
To factor this in, the user can write the DT value to the
offset register. It is then automatically added to or
subtracted from the temperature measurement by the
ADT7461.
" Some CPU manufacturers specify the high and low
current levels of the substrate transistors. The high
current level of the ADT7461, I
HIGH
, is 96 mA, and the
low level current, I
LOW
, is 6 mA. If the ADT7461
current levels do not match the current levels specified
by the CPU manufacturer, it may become necessary to
remove an offset. The CPUs data sheet advises whether
this offset needs to be removed and how to calculate it.
This offset may be programmed to the offset register. It
is important to note that if more than one offset must be
considered, the algebraic sum of these offsets must be
programmed to the offset register.
If a discrete transistor is being used with the ADT7461,
the best accuracy is obtained by choosing devices according
to the following criteria:
" Base-emitter voltage greater than 0.25 V at 6 mA, at the
highest operating temperature.
" Base-emitter voltage less than 0.95 V at 100 mA, at the
lowest operating temperature.
" Base resistance less than 100 W.
" Small variation in h
FE
(50 to 150) that indicates tight
control of V
BE
characteristics.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADT7461ARMZ-2REEL | 功能描述:IC SENSOR TEMP DGTL 2CH 8MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 熱管理 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 功能:溫度監(jiān)控系統(tǒng)（傳感器） 傳感器類型:內(nèi)部和外部 感應(yīng)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(yuǎn)程（最大值） 拓?fù)?ADC，比較器，寄存器庫 輸出類型:2 線 SMBus? 輸出警報(bào):無 輸出風(fēng)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(yīng)商設(shè)備封裝:SOT-23-8 包裝:Digi-Reel® 其它名稱:296-22675-6 |
| ADT7461ARMZ-2REEL7 | 功能描述:IC SENSOR TEMP DGTL 2CH 8MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 熱管理 系列:- 標(biāo)準(zhǔn)包裝:1 系列:- 功能:溫度監(jiān)控系統(tǒng)（傳感器） 傳感器類型:內(nèi)部和外部 感應(yīng)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(yuǎn)程（最大值） 拓?fù)?ADC，比較器，寄存器庫 輸出類型:2 線 SMBus? 輸出警報(bào):無 輸出風(fēng)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(yīng)商設(shè)備封裝:SOT-23-8 包裝:Digi-Reel® 其它名稱:296-22675-6 |
| ADT7461ARMZ-2RL7 | 功能描述:板上安裝溫度傳感器 EXT TMP RGE IC 1C TDM SRC 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 |
| ADT7461ARMZ-R2 | 制造商:ON Semiconductor 功能描述:ADT7461ARMZ-2REEL |
| ADT7461ARMZ-R7 | 功能描述:板上安裝溫度傳感器 EXT TMP RGE IC 1C TDM SRC 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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