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參數(shù)資料
| 型號： | LM95213CISD |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 溫度/濕度傳感器 |
| 英文描述： | 2-Diode Input and Local Digital Temperature Sensor with Two-Wire Interface and TCRIT Outputs |
| 中文描述： | DIGITAL TEMP SENSOR-SERIAL, 11BIT(s), 2Cel, SQUARE, SURFACE MOUNT |
| 封裝： | LLP-14 |
| 文件頁數(shù)： | 29/34頁 |
| 文件大?。?/td> | 415K |
| 代理商： | LM95213CISD |
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3.0 Applications Hints
The LM95213 can be applied easily in the same way as other
integrated-circuit temperature sensors, and its remote diode
sensing capability allows it to be used in new ways as well. It
can be soldered to a printed circuit board, and because the
path of best thermal conductivity is between the die and the
pins, its temperature will effectively be that of the printed cir-
cuit board lands and traces soldered to the LM95213's pins.
This presumes that the ambient air temperature is almost the
same as the surface temperature of the printed circuit board;
if the air temperature is much higher or lower than the surface
temperature, the actual temperature of the LM95213 die will
be at an intermediate temperature between the surface and
air temperatures. Again, the primary thermal conduction path
is through the leads, so the circuit board temperature will con-
tribute to the die temperature much more strongly than will the
air temperature.
To measure temperature external to the LM95213's die, in-
corporates remote diode sensing technology. This diode can
be located on the die of a target IC, allowing measurement of
the IC's temperature, independent of the LM95213's temper-
ature. A discrete diode can also be used to sense the tem-
perature of external objects or ambient air. Remember that a
discrete diode's temperature will be affected, and often dom-
inated, by the temperature of its leads. Most silicon diodes do
not lend themselves well to this application. It is recommend-
ed that an MMBT3904 transistor base emitter junction be
used with the collector tied to the base.
The LM95213 can measure a diode-connected transistor
such as the MMBT3904 or the thermal diode found in an AMD
processor or FPGA. The LM95213 has been optimized to
measure the remote thermal diode integrated in a typical
MMBT3904 transistor. The offset register can be used to cal-
ibrate for other thermal diodes easily. The LM9513 deos not
include TruTherm
technology that allows sensing of sub-
micron geometry process thermal diodes. For this applicaiton
the LM95233 would be better suitted.
The LM95233 has been specifically optimized to measure the
remote thermal diode integrated in a typical Intel
processor
on 65nm or 90 nm process or an MMBT3904 transistor. Using
the Remote Diode Model Select register found in the
LM95233 any of the two remote inputs can be optimized for
a typical Intel processor on 65nm or 90nm process or an
MMBT3904.
3.1 DIODE NON-IDEALITY
3.1.1 Diode Non-Ideality Factor Effect on Accuracy
When a transistor is connected as a diode, the following re-
lationship holds for variables V
BE
, T and I
F
:
(1)
where:
q = 1.6×10
19
Coulombs (the electron charge),
T = Absolute Temperature in Kelvin
k = 1.38×10
23
joules/K (Boltzmann's constant),
η
is the non-ideality factor of the process the diode is
manufactured on,
I
S
= Saturation Current and is process dependent,
I
f
= Forward Current through the base-emitter junction
V
BE
= Base-Emitter Voltage drop
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
/ I
) 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 8
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.
National invented TruTherm beta cancellation technology us-
es the transistor equation,
Equation 5
, which is a more accu-
rate representation of the topology of the thermal diode found
in some sub-micron FPGAs or processors.
(5)
29
www.national.com
L
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參數(shù)描述 |
|---|---|
| LM95213CISD/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 |
| LM95213CISDX | 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 |
| LM95213CISDX/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 |
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