參數(shù)資料
型號(hào)： ADT7411ARQ
廠商： Analog Devices, Inc.
元件分類(lèi)： 溫度/濕度傳感器
英文描述： SPI/I2C Compatible, 10-Bit Digital Temperature Sensor and 8-Channel ADC
中文描述： SPI/I2C兼容，10位數(shù)字溫度傳感器和8通道ADC
文件頁(yè)數(shù)： 18/36頁(yè)
文件大?。?/td> 456K
代理商： ADT7411ARQ
ADT7411
measurement sensor could change and therefore an offset is
added to the measured value to enable the transfer function to
match the thermal characteristics. This offset is added before
the temperature data is stored. The offset value used is stored in
the internal temperature offset register.
External Temperature Measurement
The ADT7411 can measure the temperature of one external
diode sensor or diode-connected transistor.
Rev. A | Page 18 of 36
The forward voltage of a diode or diode-connected transistor,
operated at a constant current, exhibits a negative temperature
coefficient of about 2 mV/°C. Unfortunately, the absolute
value of V
BE
varies from device to device, and individual
calibration is required to null this out, so the technique is
unsuitable for mass production.
The technique used in the ADT7411 is to measure the change in
V
BE
when the device is operated at two different currents.
This is given by:
( )
In
q
KT
V
BE
×
=
where:
K is Boltzmann’s constant
q is the charge on the carrier
T is the absolute temperature in Kelvin
N is the ratio of the two currents
Figure 23 shows the input signal conditioning used to measure
the output of an external temperature sensor. This figure shows
the external sensor as a substrate transistor, provided for temp-
erature monitoring on some microprocessors, but it could
equally well be a discrete transistor.
If a discrete transistor is used, the collector will not be
grounded, and should be linked to the base. If a PNP transistor
is used, the base is connected to the D input and the emitter to
the D+ input. If an NPN transistor is used, the emitter is con-
nected to the D input and the base to the D+ input. A 2N3906
is recommended as the external transistor.
To prevent ground noise from interfering with the measure-
ment, the more negative terminal of the sensor is not referenced
to ground but is biased above ground by an internal diode at the
D input. As the sensor is operating in a noisy environment, C1
is provided as a noise filter. See the Layout Considerations
section for more information on C1.
To measure V
BE
, the sensor is switched between operating
currents of I, and N × I. The resulting waveform is passed
through a low-pass filter to remove noise, then to a chopper-
stabilized amplifier that performs the functions of amplification
and rectification of the waveform to produce a dc voltage
proportional to V
BE
. This voltage is measured by the ADC to
give a temperature output in 10-bit twos complement format. To
further reduce the effects of noise, digital filtering is performed
by averaging the results of 16 measurement cycles.
Layout Considerations
Digital boards can be electrically noisy environments, and care
must be taken to protect the analog inputs from noise, particu-
larly when measuring the very small voltages from a remote
diode sensor. The following precautions should be taken:
1.
Place the ADT7411 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 be 4 inches to 8 inches.
2.
Route the D+ and D tracks close together, in parallel, with
grounded guard tracks on each side. Provide a ground
plane under the tracks if possible.
3.
Use wide tracks to minimize inductance and reduce noise
pickup. A 10 mil track minimum width and spacing is
recommended (see Figure 28).
0
GND
D+
D–
GND
10 MIL
10 MIL
10 MIL
10 MIL
10 MIL
10 MIL
10 MIL
Figure 28. Arrangement of Signal Tracks
Try to minimize the number of copper/solder joints, which
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.
4.
Thermocouple effects should not be a major problem as
1°C corresponds to about 240 μV, and thermocouple
voltages are about 3 μV/°C of temperature difference.
Unless there are two thermocouples with a big temperature
differential between them, thermocouple voltages should
be much less than 200 mV.
5.
Place 0.1 μF bypass and 2200 pF input filter capacitors
close to the ADT7411.
6.
If the distance to the remote sensor is more than 8 inches,
the use of twisted-pair cable is recommended. This will
work up to about 6 feet to 12 feet.
7.
For long distances (up to 100 feet) use shielded twisted-
pair cable, such as Belden #8451 microphone cable.
Connect the twisted pair to D+ and D and the shield to
GND close to the ADT7411. Leave the remote end of the
shield unconnected to avoid ground loops.
相關(guān)PDF資料
PDF描述
ADT7411ARQ-REEL Circular Connector; No. of Contacts:26; Series:LJT07R; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:17; Circular Contact Gender:Pin; Circular Shell Style:Jam Nut Receptacle; Insert Arrangement:17-26
ADT7411ARQ-REEL7 Circular Connector; No. of Contacts:55; Series:LJT07R; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:17; Circular Contact Gender:Pin; Circular Shell Style:Jam Nut Receptacle; Insert Arrangement:17-35
ADT7411ARQZ-REEL Circular Connector; No. of Contacts:55; Series:LJT07R; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:17; Circular Contact Gender:Pin; Circular Shell Style:Jam Nut Receptacle; Insert Arrangement:17-35
ADT7411ARQZ-REEL7 Circular Connector; No. of Contacts:55; Series:LJT07R; Body Material:Aluminum; Connecting Termination:Crimp; Connector Shell Size:17; Circular Contact Gender:Socket; Circular Shell Style:Jam Nut Receptacle; Insert Arrangement:17-35
ADT7411ARQZ10 LJT 6C 6#12 SKT RECP
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
ADT7411ARQ-REEL 功能描述:IC SENSOR TEMP 10BIT ADC 16QSOP RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 熱管理 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:SilentSense™ 功能:溫度監(jiān)控系統(tǒng)（傳感器） 傳感器類(lèi)型:內(nèi)部和外部 感應(yīng)溫度:-55°C ~ 125°C，外部傳感器 精確度:±2°C 本地（最大），±3°C 遠(yuǎn)程（最大） 拓?fù)?ADC（三角積分型），比較器，寄存器庫(kù) 輸出類(lèi)型:I²C?/SMBus? 輸出警報(bào):是 輸出風(fēng)扇:是 電源電壓:2.7 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-TSSOP，8-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:8-MSOP 包裝:帶卷 (TR) 其它名稱(chēng):MIC284-2BMMTRMIC284-2BMMTR-ND
ADT7411ARQ-REEL7 功能描述:IC SENSOR TEMP 10BIT ADC 16QSOP RoHS:否 類(lèi)別:集成電路 (IC) >> PMIC - 熱管理 系列:- 標(biāo)準(zhǔn)包裝:2,500 系列:SilentSense™ 功能:溫度監(jiān)控系統(tǒng)（傳感器） 傳感器類(lèi)型:內(nèi)部和外部 感應(yīng)溫度:-55°C ~ 125°C，外部傳感器 精確度:±2°C 本地（最大），±3°C 遠(yuǎn)程（最大） 拓?fù)?ADC（三角積分型），比較器，寄存器庫(kù) 輸出類(lèi)型:I²C?/SMBus? 輸出警報(bào):是 輸出風(fēng)扇:是 電源電壓:2.7 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-TSSOP，8-MSOP（0.118"，3.00mm 寬） 供應(yīng)商設(shè)備封裝:8-MSOP 包裝:帶卷 (TR) 其它名稱(chēng):MIC284-2BMMTRMIC284-2BMMTR-ND
ADT7411ARQZ 功能描述:IC DGTL TEMP SNSR 8CH ADC 16QSOP RoHS:是 類(lèi)別:集成電路 (IC) >> PMIC - 熱管理 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- 功能:溫度開(kāi)關(guān) 傳感器類(lèi)型:內(nèi)部 感應(yīng)溫度:85°C 分界點(diǎn) 精確度:±6°C（最小值） 拓?fù)?ADC（三角積分型），比較器，寄存器庫(kù) 輸出類(lèi)型:開(kāi)路漏極 輸出警報(bào):是 輸出風(fēng)扇:是 電源電壓:2.7 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:SC-74A，SOT-753 供應(yīng)商設(shè)備封裝:SOT-23-5 包裝:帶卷 (TR) 其它名稱(chēng):ADT6501SRJZP085RL7-ND
ADT7411ARQZ 制造商:Analog Devices 功能描述:Temperature Sensor IC
ADT7411ARQZ1 制造商:AD 制造商全稱(chēng):Analog Devices 功能描述:SPI??-/I2C??-Compatible, 10-Bit Digital Temperature Sensor and 8-Channel ADC
發(fā)布緊急采購(gòu)，3分鐘左右您將得到回復(fù)。

采購(gòu)需求

(若只采購(gòu)一條型號(hào)，填寫(xiě)一行即可)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

發(fā)布成功！您可以繼續(xù)發(fā)布采購(gòu)。也可以進(jìn)入我的后臺(tái)，查看報(bào)價(jià)

*型號(hào) *數(shù)量 廠商 批號(hào) 封裝
添加更多采購(gòu)

我的聯(lián)系方式

*
*
*