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Precision And Low Power Remote Sensing Concept,Did You Understand That??

Auth:亿配芯城 Date:2019/11/18 Source:www.yibeiic.com Visit:25 Related Key Words: Low power consumption High precision Bias amplifier
This solution combines low power consumption in recent years、Research progress in high precision amplification,Equal low power consumption、High reliability wirelessMeshInternet function。Support for implementing these solutions is zero drift、Low input bias amplifierLTC2063withLTP5901-IPM,The former is the highest2μACurrent operation,The latter consumes less current in sleep mode1.5μA。The power consumption of these devices is low enough,Even a copper and zinc electrode can be used(Every four square inches),And a battery-powered combination of electrolytes formed from the internals of lemon。


wirelessMeshThe internet


Measurements implemented and retrieved over a wireless network in an industrial environment rarely require high speed,But they usually require high reliability and security,Also requires low power operation,To maximize battery run time。LTP5901-IPMin802.15.4eForming a node or a wireless networkSmartMesh®IP Mote。LTP5901-IPMIntegrated one10Bit、0Vto1.8V ADC,And a built-inARM®Cortex®-M3 32Bit microprocessor,Can be tested by simple programming。This terminal is used for security、reliability、Low power consumption、Flexibility and programmability。


Four detection applications


In general,The following circuit designs do not require deep rocket knowledge.。but,They are neat、Efficient,Is customized for specific applications。These designs don't need to be complicated;Actually,Complex design only increases cost and reliability risks。


One sensor per input in the circuit,Output voltage by processing sensor output。useLTP5901-IPM 10BitADCAs input,Each circuit tries to map the input,cover0Vto1.8VMost of the range。



Basic battery voltage detection


Figure1Demonstrates a typical in-phase overall gain negative feedback op amp configuration,Can detect partial pressure。LTP5901InputADCRange is0Vto1.8V。R1withR2Reduce battery voltage with minimal quiescent current,To extend battery life。LTC2063Input bias current is very low,Even if the above two resistance values ​​are high, it will not affect the final10BitADCAccuracy。LTC2063Minimizes supply current,Provides zero drift advantages over time and temperature。


Figure1:Simple battery voltage detection



Current Detection


The beauty of battery-powered and isolated electronics lies in:It can be grounded at any position。In the most convenient circuit topology,我们可以in不丧失通用性of情况下检测Current,Also place the terminal in any location related to local grounding。Unipolar current,E.g4mAto20mAIndustrial loop,One can use traditional low-side topologies to safely detect currents associated with local grounding。Figure2Shows that current flows through a very small resistorR2,Resulting in a detection voltage。Because of the zero drift of the amplifier、Very low offset voltage performance and other reasons,This input voltage can be very small。In the circuit shown in the figure,via501mΩThe gain of the input generated by the sense resistor is increased101 V/V。在20mATime,VOUTYes1.012V。You can choose other values ​​to get the most out of it.ADC的1.8Vrange。


Figure2:Current detection circuit


resistanceR4Relative resistance is relatively low,YesLTC2063Low-impedance shunt for input capacitor。therefore,Large resistanceR1The interaction between the feedback resistor and the input capacitor does not stabilize。


The constructed circuit is optimized,For testing0mAto35mA电流、0Vto1.8V ADCMapping range。


Irradiance meter


Figure3The circuit shown can be used to measure the short circuit current of a solar cell。In short circuit current mode,The current and irradiance of silicon and other solar cells are highly linear。Short circuit current is0VSolar cell current。Figure3The circuit in the circuit does not guarantee that the solar cell accurately reaches the maximum current.0V;but,Even in full sunlight, the current is20mA,The voltage is only10mV。On a solar cell10mVLevel in itI-VActually short circuit on the curve。


Figure3:Short-circuit irradiance measurement using solar cells










热电偶电压可以是正压也可以是负压。图4所示的电路融合采用微功率基准电压源和微功率放大器来检测极小的正负电压。幸运的是,如果热电偶与被测器件(DUT)电气隔离,则可以置于任何方便的电压域中。图4中的示例使用LT6656-1.25,在1.25V时偏置热电偶。电路输出是基于1.25V基准电压源的小热电偶电压的高增益版本。对于这种配置,0V至1.8V的ADC范围相当合理。如果不使用零漂移、低失调放大器,则无法实现2000 V/V左右的极高增益。








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