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參數(shù)資料
| 型號： | LM95245 |
| 廠商： | National Semiconductor Corporation |
| 元件分類： | 溫度/濕度傳感器 |
| 英文描述： | Precision Remote Diode Digital Temperature Sensor with TruTherm⑩ BJT Beta Compensation Technology for 45nm Process |
| 中文描述： | 高精度遠(yuǎn)程二極管數(shù)字溫度傳感器的45納米工藝的TruTherm⑩晶體管測試補償技術(shù) |
| 文件頁數(shù)： | 21/24頁 |
| 文件大?。?/td> | 342K |
| 代理商： | LM95245 |
30015143
FIGURE 7. Thermal Diode Current Paths
In the active region, the -1 term is negligible and may be elim-
inated, yielding the following equation
(2)
In
Equation 2
, η
and I
are dependant upon the process that
was used in the fabrication of the particular diode. By forcing
two currents with a very controlled ratio(I
F2
/ I
F1
) and measur-
ing the resulting voltage difference, it is possible to eliminate
the I
term. Solving for the forward voltage difference yields
the relationship:
(3)
Solving
Equation 3
for temperature yields:
(4)
Equation 4
holds true when a diode connected transistor such
as the MMBT3904 is used. When this “diode” equation is ap-
plied to an integrated diode such as a processor transistor
with its collector tied to GND as shown in
Figure 7
it will yield
a wide non-ideality spread. This wide non-ideality spread is
not due to true process variation but due to the fact that
Equation 4
is an approximation.
TruTherm technology uses the transistor (BJT) equation,
Equation 5
, which is a more accurate representation of the
topology of the thermal diode found in an FPGA or processor.
(5)
TruTherm should only be enabled when measuring the tem-
perature of a transistor integrated as shown in the processor
of
Figure 7
, because
Equation 5
only applies to this topology.
3.1.2 Calculating Total System Accuracy
The voltage seen by the LM95245 also includes the I
R
volt-
age drop of the series resistance. The non-ideality factor,
η
,
is the only other parameter not accounted for and depends
on the diode that is used for measurement. Since
Δ
V
is
proportional to both
η
and T, the variations in
η
cannot be
distinguished from variations in temperature. Since the non-
ideality factor is not controlled by the temperature sensor, it
will directly add to the inaccuracy of the sensor. Intel thermal
diode specifications for processors on 45nm process were not
available at the publication of this document, therefore fol-
lowing examples will use the 65nm thermal diode specifica-
tions. For the for Intel processor on 65nm process, Intel
specifies a +4.06%/0.897% variation in
η
from part to part
when the processor diode is measured by a circuit that as-
sumes diode equation,
Equation 4
, as true. As an example,
assume a temperature sensor has an accuracy specification
of ±1.0°C at a temperature of 80°C (353 Kelvin) and the pro-
cessor diode has a non-ideality variation of +1.19%/0.27%.
The resulting system accuracy of the processor temperature
being sensed will be:
T
ACC
= + 1.0°C + (+4.06% of 353 K) = +15.3 °C
and
T
ACC
= - 1.0°C + (0.89% of 353 K) = 4.1 °C
TrueTherm technology uses the transistor equation,
Equation
4
, resulting in a non-ideality spread that truly reflects the pro-
cess variation which is very small. The transistor equation
non-ideality spread is ±0.39% for the Pentium 4 processor on
90 nm process. The resulting accuracy when using TruTherm
technology improves to:
T
ACC
= ±0.75°C + (±0.39% of 353 K) = ± 2.16 °C
The next error term to be discussed is that due to the series
resistance of the thermal diode and printed circuit board
traces. The thermal diode series resistance is specified on
most processor data sheets. For Intel processors in 65 nm
process, this is specified at 4.52
typical. The LM95245 ac-
commodates the typical series resistance of Intel Processor
on 65 nm process. The error that is not accounted for is the
spread of the processor's series resistance, that is 2.79
to
6.24
or ±1.73
. The equation to calculate the temperature
error due to series resistance (T
ER
) for the LM95245 is simply:
21
www.national.com
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM95245_08 | 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Precision Remote Diode Digital Temperature Sensor with TruTherm㈢ BJT Beta Compensation Technology for 45nm Process |
| LM95245CIM | 功能描述:板上安裝溫度傳感器 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 |
| LM95245CIM/NOPB | 功能描述:板上安裝溫度傳感器 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 |
| LM95245CIMM | 功能描述:板上安裝溫度傳感器 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 |
| LM95245CIMM/NOPB | 功能描述:板上安裝溫度傳感器 TS W/ TRUTHERM FOR 45NM PROCESS 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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