參數(shù)資料
型號(hào)： LMP90079MH/NOPB
廠商： NATIONAL SEMICONDUCTOR CORP
元件分類： 模擬信號(hào)調(diào)理
英文描述： SPECIALTY ANALOG CIRCUIT, PDSO28
封裝： LEAD FREE, PLASTIC, MO-153, TSSOP-28
文件頁數(shù)： 42/62頁
文件大?。?/td> 1721K
代理商： LMP90079MH/NOPB
17.6.2 Thermocouple and IC Analog Temperature
30169799
FIGURE 39. Thermocouple with CJC
The LMP900xx is also ideal for thermocouple temperature
applications. Thermocouples have several advantages that
make them popular in many industrial and medical applica-
tions. Compare to RTDs, thermistors, and IC sensors, ther-
mocouples are the most rugged, least expensive, and can
operate over the largest temperature range.
A thermocouple is a sensor whose junction generates a dif-
ferential voltage, VIN, that is relative to the temperature dif-
ference (Thot – Tcold). Thot is also known as the measuring
junction or “hot” junction, which is placed at the measured
environment. Tcold is also known as the reference or “cold”
junction, which is placed at the measuring system environ-
ment.
Because a thermocouple can only measure a temperature
difference, it does not have the ability to measure absolute
temperature. To determine the absolute temperature of the
measured environment (Thot), a technique known as cold
junction compensation (CJC) must be used.
In a CJC technique, the “cold” junction temperature, Tcold, is
sensed by using an IC temperature sensor, such as the
LM94022. The temperature sensor should be placed within
close proximity of the reference junction and should have an
isothermal connection to the board to minimize any potential
temperature gradients.
Once Tcold is obtained, use a standard thermocouple look-
up-table to find its equivalent voltage. Next, measure the
differential thermocouple voltage and add the equivalent cold
junction voltage. Lastly, convert the resulting voltage to tem-
perature using a standard thermocouple look-up-table.
For example, assume Tcold = 20°C. The equivalent voltage
from a type K thermocouple look-up-table is 0.798 mV. Next,
add the measured differential thermocouple voltage to the
Tcold equivalent voltage. For example, if the thermocouple
voltage is 4.096 mV, the total would be 0.798 mV + 4.096 mV
= 4.894 mV. Referring to the type K thermocouple table gives
a temperature of 119.37°C for 4.894 mV.
47
www.national.com
LMP90080/LMP90079/LMP90078/LMP90077
相關(guān)PDF資料
PDF描述
LMP90079MHE/NOPB SPECIALTY ANALOG CIRCUIT, PDSO28
LMP90078MHX/NOPB SPECIALTY ANALOG CIRCUIT, PDSO28
LMP90078MHE/NOPB SPECIALTY ANALOG CIRCUIT, PDSO28
LMP90079MHX/NOPB SPECIALTY ANALOG CIRCUIT, PDSO28
LMP90080MHE/NOPB SPECIALTY ANALOG CIRCUIT, PDSO28
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LMP90079MHX/NOPB 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32
LMP90080 制造商:NSC 制造商全稱:National Semiconductor 功能描述:Sensor AFE System: Multi-Channel, Low-Power 16-Bit
LMP90080MH/NOPB 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32
LMP90080MHE/NOPB 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32
LMP90080MHX/NOPB 功能描述:模數(shù)轉(zhuǎn)換器 - ADC RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 結(jié)構(gòu):Sigma-Delta 轉(zhuǎn)換速率:125 SPs to 8 KSPs 分辨率:24 bit 輸入類型:Differential 信噪比:107 dB 接口類型:SPI 工作電源電壓:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:VQFN-32
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