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| 型号： | AD7817ARZ-REEL7 |
| 厂商： | Analog Devices Inc |
| 文件页数： | 13/20页 |
| 文件大小： | 279K |
| 描述： | IC ADC 10BIT W/TEMP SNSR 16SOIC |
| 标准包装： | 1,000 |
| 功能： | 温度监控系统（传感器） |
| 传感器类型： | 内部 |
| 感应温度： | -55°C ~ 125°C |
| 精确度： | ±2°C |
| 拓扑： | ADC，多路复用器，寄存器库 |
| 输出类型： | MICROWIRE?，QSPI?，SPI? |
| 输出警报： | 是 |
| 输出风扇： | 是 |
| 电源电压： | 2.7 V ~ 5.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-SOIC |
| 包装： | 带卷 (TR) |
REV. C
AD7816/AD7817/AD7818
13
For example, if the result of a conversion on Channel 0 was
1000000000 (512 Dec), the ambient temperature is equal to
103癈 + (512/4) = +25癈.
Table II below shows some ADC codes for various temperatures.
Table II. Temperature Sensor Output
ADC Code
Temperature
00 1100 0000
55癈
01 0011 1000
25癈
01 1001 1100
0癈
10 0000 0000
+25癈
10 0111 1000
+55癈
11 1001 0000
+125癈
TEMPERATURE MEASUREMENT ERROR DUE TO
REFERENCE ERROR
The AD7816, AD7817, and AD7818 are trimmed using a pre-
cision 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.
CODE (Dec) = ([113.3285 ?SPAN class="pst AD7818ARZ_2284549_5"> K ?SPAN class="pst AD7818ARZ_2284549_5"> T]/[q ?SPAN class="pst AD7818ARZ_2284549_5"> V
REF
]
0.6646) ?/SPAN> 1024
where:
K = Boltzmanns Constant, 1.38 ?/SPAN> 10
23
q = Charge on an electron, 1.6 ?/SPAN> 10
19
T = Temperature (K)
So, for example, to calculate the ADC code at 25癈
CODE = ([113.3285 ?/SPAN> 298 ?/SPAN> 1.38 ?/SPAN> 10
23
]/[1.6 ?SPAN class="pst AD7818ARZ_2284549_7"> 10
19
?2.5]
0.6646) ?SPAN class="pst AD7818ARZ_2284549_7"> 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癈 would be 2.2 LSBs (0.5癈) and
16 LSBs (4癈) at 125癈.
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 between
4 mW and 6.5 mW of power. Because a thermal impedance 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 sec-
onds. 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
0.50
0.05
0
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
0.25
0.05
0
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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相关代理商/技术参数 |
参数描述 |
|---|---|
| AD7817BR | 制造商:Analog Devices 功能描述:ADC Single SAR 100ksps 10-bit Serial 16-Pin SOIC N 制造商:Rochester Electronics LLC 功能描述:4 CH. ADC W/ON-CHIP TEMP SENSOR I.C. - Bulk |
| AD7817BR-REEL | 制造商:Analog Devices 功能描述:ADC Single SAR 100ksps 10-bit Serial 16-Pin SOIC N T/R 制造商:Rochester Electronics LLC 功能描述:4 CH. ADC W/ON-CHIP TEMP SENSOR I.C. - Tape and Reel |
| AD7817BR-REEL7 | 制造商:Analog Devices 功能描述:ADC Single SAR 100ksps 10-bit Serial 16-Pin SOIC N T/R 制造商:Rochester Electronics LLC 功能描述:4 CH. ADC W/ON-CHIP TEMP SENSOR I.C. - Tape and Reel |
| AD7817BRU | 功能描述:IC ADC 10BIT W/TEMP SNSR 16TSSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 热管理 系列:- 标准包装:2,500 系列:SilentSense™ 功能:温度监控系统（传感器） 传感器类型:内部和外部 感应温度:-55°C ~ 125°C，外部传感器 精确度:±2°C 本地（最大），±3°C 远程（最大） 拓扑:ADC（三角积分型），比较器，寄存器库 输出类型:I²C?/SMBus? 输出警报:是 输出风扇:是 电源电压:2.7 V ~ 5.5 V 工作温度:-55°C ~ 125°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-MSOP 包装:带卷 (TR) 其它名称:MIC284-2BMMTRMIC284-2BMMTR-ND |
| AD7817BRU-REEL | 制造商:Analog Devices 功能描述:ADC Single SAR 100ksps 10-bit Serial 16-Pin TSSOP T/R 制造商:Rochester Electronics LLC 功能描述:4 CH. ADC W/ON-CHIP TEMP SENSOR I.C. - Tape and Reel |
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