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| 型號： | ADT7519ARQ-REEL |
| 廠商： | Analog Devices, Inc. |
| 元件分類： | 溫度/濕度傳感器 |
| 英文描述： | SPI/I2C Compatible, Temperature Sensor, Four Channel ADC and Quad Voltage Output DAC |
| 中文描述： | SPI/I2C兼容，溫度傳感器，四通道ADC和四路電壓輸出DAC |
| 文件頁數(shù)： | 27/44頁 |
| 文件大?。?/td> | 1350K |
| 代理商： | ADT7519ARQ-REEL |
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ADT7516/ADT7517/ADT7519
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
connected to the D– input and the base to the D+ input.
Rev. A | Page 27 of 44
A 2N3906 is recommended as the external transistor.
To prevent ground noise interfering with the measurement, 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 ADT7516/ADT7517/ADT7519 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.
GND
D+
D–
GND
10 MIL
10 MIL
10 MIL
10 MIL
10 MIL
10 MIL
10 MIL
0
Figure 54. Arrangement of Signal Tracks
4.
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.
Thermocouple effects should not be a major problem
because 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 ADT7516/ADT7517/ADT7519.
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. Con-
nect the twisted pair to D+ and D–. and the shield to GND
close to the ADT7516/ADT7517/ADT7519. Leave the
remote end of the shield unconnected to avoid ground
loops.
Because the measurement technique uses switched current
sources, excessive cable and/or filter capacitance can affect the
measurement. When using long cables, the filter capacitor may
be reduced or removed.
Cable resistance can also introduce errors. Series resistance of
1 introduces about 0.5°C error.
Temperature Value Format
One LSB of the ADC corresponds to 0.25°C. The ADC can
theoretically measure a temperature span of 255°C. The internal
temperature sensor is guaranteed to a low value limit of –40°C.
It is possible to measure the full temperature span using the
external temperature sensor. The temperature data format is
shown in Table 9.
The result of the internal or external temperature measure-
ments is stored in the temperature value registers, and is com-
pared with limits programmed into the internal or external high
and low registers.
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相關代理商/技術參數(shù) |
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|---|---|
| ADT7519ARQ-REEL7 | 制造商:Analog Devices 功能描述:Temp Sensor Digital Serial (4-Wire, SPI, I2C) 16-Pin QSOP T/R 制造商:Analog Devices 功能描述:TEMP SENSOR DGTL SERL (4-WIRE, SPI) 16QSOP - Tape and Reel |
| ADT7519ARQZ | 功能描述:IC TEMP SNSR QUAD DAC 16-QSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 熱管理 系列:- 標準包裝:3,000 系列:- 功能:溫度開關 傳感器類型:內(nèi)部 感應溫度:85°C 分界點 精確度:±6°C（最小值） 拓撲:ADC（三角積分型），比較器，寄存器庫 輸出類型:開路漏極 輸出警報:是 輸出風扇:是 電源電壓:2.7 V ~ 5.5 V 工作溫度:-55°C ~ 125°C 安裝類型:表面貼裝 封裝/外殼:SC-74A，SOT-753 供應商設備封裝:SOT-23-5 包裝:帶卷 (TR) 其它名稱:ADT6501SRJZP085RL7-ND |
| ADT7519ARQZ1 | 制造商:AD 制造商全稱:Analog Devices 功能描述:SPI/I2C Compatible, Temperature Sensor, Four Channel ADC and Quad Voltage Output DAC |
| ADT7519ARQZ1-REEL | 制造商:AD 制造商全稱:Analog Devices 功能描述:SPI/I2C Compatible, Temperature Sensor, Four Channel ADC and Quad Voltage Output DAC |
| ADT7519ARQZ1-REEL7 | 制造商:AD 制造商全稱:Analog Devices 功能描述:SPI/I2C Compatible, Temperature Sensor, Four Channel ADC and Quad Voltage Output DAC |
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