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參數(shù)資料
| 型號： | LM95241CIMMX |
| 廠商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分類： | 溫度/濕度傳感器 |
| 英文描述： | Dual Remote Diode Temperature Sensor with SMBus Interface and TruTherm⑩ Technology (65nm/90nm) |
| 中文描述： | DIGITAL TEMP SENSOR-DUAL TRIP POINT |
| 封裝： | MO-187, MSOP-8 |
| 文件頁數(shù)： | 16/19頁 |
| 文件大?。?/td> | 708K |
| 代理商： | LM95241CIMMX |
2.0 LM95241 Registers
(Continued)
2.7 MANUFACTURERS ID REGISTER
(Read Address FEh) The default value is 01h.
2.8 DIE REVISION CODE REGISTER
(Read Address FFh) The default value is A4h. This register will increment by 1 every time there is a revision to the die by National
Semiconductor.
3.0 Applications Hints
The LM95241 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 be-
cause the path of best thermal conductivity is between the
die and the pins, its temperature will effectively be that of the
printed circuit board lands and traces soldered to the
LM95241’s pins. This presumes that the ambient air tem-
perature 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 tempera-
ture of the LM95241 die will be at an intermediate tempera-
ture between the surface and air temperatures. Again, the
primary thermal conduction path is through the leads, so the
circuit board temperature will contribute to the die tempera-
ture much more strongly than will the air temperature.
To measure temperature external to the LM95241’s die, use
a remote diode. This diode can be located on the die of a
target IC, allowing measurement of the IC’s temperature,
independent of the LM95241’s temperature. A discrete diode
can also be used to sense the temperature of external
objects or ambient air. Remember that a discrete diode’s
temperature will be affected, and often dominated, by the
temperature of its leads. Most silicon diodes do not lend
themselves well to this application. It is recommended that a
2N3904 transistor base emitter junction be used with the
collector tied to the base.
The LM95241’s TruTherm technology allows accurate sens-
ing of integrated thermal diodes, such as those found on
sub-micron geometry processors. With TruTherm technol-
ogy turned off, the LM95241 can measure a diode con-
nected transistor such as the 2N3904 or MMBT3904.
The LM95241 has been optimized to measure the remote
thermal diode integrated in a Intel processor on 65nm or
90nm process or an MMBT3904 transistor. Using the Re-
mote Diode Model Select register either pair of remote inputs
can be assigned to measure either a Intel processor on
65nm or 90nm process or an MMBT3904 transistor.
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
relationship holds for variables V
BE
, T and I
F
:
(1)
where:
q = 1.6x10
19
Coulombs (the electron charge),
T = Absolute Temperature in Kelvin
k = 1.38x10
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
eliminated, 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
measuring the resulting voltage difference, it is possible to
eliminate the I
term. Solving for the forward voltage differ-
ence 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 applied to an integrated diode such as a processor tran-
sistor with its collector tied to GND as shown in
Figure 3
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 equation,
Equation
(5)
, which is a more accurate representation of the topology
of the thermal diode found in an FPGA or processor.
(5)
L
www.national.com
16
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LM95241CIMMX/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 |
| LM95241CIMMX-1 | 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 |
| LM95241CIMMX-1/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 |
| LM95241CIMMX-2 | 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 |
| LM95241CIMMX-2/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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