參數(shù)資料
型號(hào)： LM95245CIMM
廠商： National Semiconductor Corporation
元件分類(lèi)： 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(cè)試補(bǔ)償技術(shù)
文件頁(yè)數(shù)： 22/24頁(yè)
文件大小： 342K
代理商： LM95245CIMM
(6)
Solving
Equation 6
for R
equal to ±1.73
results in the
additional error due to the spread in the series resistance of
±1.07°C. The spread in error cannot be canceled out, as it
would require measuring each individual thermal diode de-
vice. This is quite difficult and impractical in a large volume
production environment.
Equation 6
can also be used to calculate the additional error
caused by series resistance on the printed circuit board. Since
the variation of the PCB series resistance is minimal, the bulk
of the error term is always positive and can simply be can-
celled out by subtracting it from the output readings of the
LM95245.
Processor Family
Transistor Equation
η
T
,
non-ideality
typ
NA
Series
R,
NA
min
NA
max
NA
Intel Processor on
45 nm process
Intel Processor on
65 nm process
0.997
1.001
1.005
4.52
Note: NA= Not Available at publication of this document.
3.2 PCB LAYOUT FOR MINIMIZING NOISE
30015117
FIGURE 8. Ideal Diode Trace Layout
In a noisy environment, such as a processor mother board,
layout considerations are very critical. Noise induced on
traces running between the remote temperature diode sensor
and the LM95245 can cause temperature conversion errors.
Keep in mind that the signal level the LM95245 is trying to
measure is in microvolts. The following guidelines should be
followed:
1.
V
should be bypassed with a 0.1 μF capacitor in
parallel with 100 pF. The 100 pF capacitor should be
placed as close as possible to the power supply pin. A
bulk capacitance of approximately 10 μF needs to be in
the near vicinity of the LM95245.
2.
A 100 pF diode bypass capacitor is recommended to filter
high frequency noise but may not be necessary. Make
sure the traces to the 100 pF capacitor are matched.
Place the filter capacitors close to the LM95245 pins.
Ideally, the LM95245 should be placed within 10 cm of
the Processor diode pins with the traces being as
straight, short and identical as possible. Trace resistance
of 1
Ω
can cause as much as 0.62°C of error. This error
can be compensated by using simple software offset
compensation.
Diode traces should be surrounded by a GND guard ring
to either side, above and below if possible. This GND
guard should not be between the D+ and D lines. In the
event that noise does couple to the diode lines it would
be ideal if it is coupled common mode. That is equally to
the D+ and D lines.
Avoid routing diode traces in close proximity to power
supply switching or filtering inductors.
Avoid running diode traces close to or parallel to high
speed digital and bus lines. Diode traces should be kept
at least 2 cm apart from the high speed digital traces.
If it is necessary to cross high speed digital traces, the
diode traces and the high speed digital traces should
cross at a 90 degree angle.
The ideal place to connect the LM95245's GND pin is as
close as possible to the Processors GND associated with
the sense diode.
Leakage current between D+ and GND and between D+
and D should be kept to a minimum. Thirteen nano-
amperes of leakage can cause as much as 0.2°C of error
in the diode temperature reading. Keeping the printed
circuit board as clean as possible will minimize leakage
current.
Noise coupling into the digital lines greater than 400 mVp-p
(typical hysteresis) and undershoot less than 500 mV below
GND, may prevent successful SMBus communication with
the LM95245. SMBus no acknowledge is the most common
symptom, causing unnecessary traffic on the bus. Although
the SMBus maximum frequency of communication is rather
low (100 kHz max), care still needs to be taken to ensure
proper termination within a system with multiple parts on the
bus and long printed circuit board traces. An RC lowpass filter
with a 3 dB corner frequency of about 40 MHz is included on
the LM95245's SMBCLK input. Additional resistance can be
added in series with the SMBDAT and SMBCLK lines to fur-
ther help filter noise and ringing. Minimize noise coupling by
keeping digital traces out of switching power supply areas as
well as ensuring that digital lines containing high speed data
communications cross at right angles to the SMBDAT and
SMBCLK lines.
3.
4.
5.
6.
7.
8.
9.
www.national.com
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參數(shù)描述
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(lèi)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-1 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
LM95245CIMM-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(lèi)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
LM95245CIMMX 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類(lèi)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
LM95245CIMMX/NOPB 功能描述:板上安裝溫度傳感器 RoHS:否 制造商:Omron Electronics 輸出類(lèi)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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