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參數(shù)資料
| 型號： | AD7818 |
| 廠商： | Analog Devices, Inc. |
| 元件分類： | 溫度/濕度傳感器 |
| 英文描述： | 10-Bit ADCs with On-Chip Temperature Sensor(單通道,10位A/D轉(zhuǎn)換器) |
| 中文描述： | 10位ADC的片上溫度傳感器（單通道，10位的A / D轉(zhuǎn)換器） |
| 文件頁數(shù)： | 12/16頁 |
| 文件大?。?/td> | 230K |
| 代理商： | AD7818 |
AD7816/AD7817/AD7818
–12–
REV. 0
For example, if the result of a conversion on Channel 0 was
1000000000 (512 Dec), the ambient temperature is equal to
–103
°
C + (512/4) = +25
°
C.
Table II below shows some ADC codes for various temperatures.
Table II. Temperature Sensor Output
ADC Code
Temperature
–55
°
C
–25
°
C
0
°
C
+25
°
C
+55
°
C
+125
°
C
00 1100 0000
01 0011 1000
01 1001 1100
10 0000 0000
10 0111 1000
11 1001 0000
TEMPERATURE MEASUREMENT ERROR DUE TO
REFERENCE ERROR
The AD7816, AD7817 and AD7818 are trimmed using a preci-
sion +2.5 V reference to give the transfer function described
previously. To show the effect of the reference tolerance on a
temperature reading, the temperature sensor transfer function
can be rewritten as a function of the reference voltage and the
temperature.
C
ODE
(
Dec
)
=
([113.3285
×
K
×
T
]
/
[
q
×
V
REF
]
–
0.6646)
×
1024
where
K
= Boltzmann’s Constant, 1.38
×
10
–23
q
= Charge on an electron, 1.6
×
10
–19
T
= Temperature (K)
So, for example, to calculate the ADC code at 25
°
C
CODE
= ([113.3285
×
298
×
1.38
×
10
–23
]/[1.6
×
10
–19
×
2.5]
– 0.6646)
×
1024
= 511.5 (200 Hex)
As can be seen from the expression, a reference error will pro-
duce a gain error. This means that the temperature measure-
ment error due to reference error will be greater at higher
temperatures. For example, with a reference error of –1%, the
measurement error at –55
°
C would be +2.2 LSBs (0.5
°
C) and
+16 LSBs (4
°
C) at +125
°
C.
SELF-HEATING CONSIDERATIONS
The AD7817 and AD7818 have an analog-to-digital conversion
function capable of a throughput rate of 100 kSPS. At this
throughput rate the AD7817 and AD7818 will consume be-
tween 4 mW and 6.5 mW of power. Because a thermal imped-
ance is associated with the IC package, the temperature of the
die will rise as a result of this power dissipation. The graphs
below show the self-heating effect in a 16-lead SOIC package.
Figures 12 and 13 show the self-heating effect on a two-layer
and four-layer PCB. The plots were generated by assembling a
heater (resistor) and temperature sensor (diode) in the package
being evaluated. In Figure 12, the heater (6 mW) is turned off
after 30 sec. The PCB has little influence on the self-heating
over the first few seconds after the heater is turned on. This can
be more clearly seen in Figure 13 where the heater is switched
off after 2 seconds. Figure 14 shows the relative effects of self-
heating in air, fluid and in thermal contact with a large heat
sink.
These diagrams represent the worst case effects of self-heating.
The heater delivered 6 mW to the interior of the package in all
cases. This power level is equivalent to the ADC continuously
converting at 100 kSPS. The effects of the self-heating can be
reduced at lower ADC throughput rates by operating on Mode
2—see Operating Modes section. When operating in this mode,
the on-chip power dissipation reduces dramatically and, as a
consequence, the self-heating effects.
TIME – secs
T
8
C
0.50
–0.050
60
10
20
30
40
50
0.45
0.30
0.15
0.10
0.05
0.40
0.35
0.25
0.20
0.00
4-LAYER PCB
2-LAYER PCB
Figure 12. Self-Heating Effect Two-Layer and
Four-Layer PCB
TIME – secs
T
8
C
0.25
–0.050
5
1
2
3
4
0.15
0.05
0.20
0.10
0.00
4-LAYER PCB
2-LAYER PCB
Figure 13. Self-Heating Effect Two-Layer and
Four-Layer PCB
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| AD7818AR | 制造商:Analog Devices 功能描述:ADC Single SAR 100ksps 10-bit Serial 8-Pin SOIC N 制造商:Rochester Electronics LLC 功能描述:1 CH. ADC W/0N-CHIP TEMP SENSOR I.C. - Bulk 制造商:Analog Devices 功能描述:SEMICONDUCTOR ((NW)) |
| AD7818ARM | 功能描述:IC ADC 10BIT W/TEMP SNSR 8-MSOP RoHS:否 類別: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 輸出類型:I²C?/SMBus? 輸出警報: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:MIC284-2BMMTRMIC284-2BMMTR-ND |
| AD7818ARM-REEL | 功能描述:IC ADC 10BIT W/TEMP SNSR 8-MSOP RoHS:否 類別: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 輸出類型:I²C?/SMBus? 輸出警報: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:MIC284-2BMMTRMIC284-2BMMTR-ND |
| AD7818ARM-REEL7 | 制造商:Analog Devices 功能描述:ADC Single SAR 100ksps 10-bit Serial 8-Pin MSOP T/R 制造商:Analog Devices 功能描述:ADC SGL SAR 100KSPS 10-BIT SERL 8MSOP - Tape and Reel |
| AD7818ARMZ | 功能描述:IC ADC 10BIT W/TEMP SENSOR 8MSOP RoHS:是 類別:集成電路 (IC) >> PMIC - 熱管理 系列:- 標(biāo)準(zhǔn)包裝:3,000 系列:- 功能:溫度開關(guān) 傳感器類型: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 輸出類型:開路漏極 輸出警報: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:ADT6501SRJZP085RL7-ND |
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