原标题：Linear LT6375±270V 共模电压差分放大器解决方案

　　Linear公司的LT6375是 ±270V是共模电压差分放大器,具有极好的DC精度,非常高的(±270V)输入共模电压和很宽电源电压范围,包括有精密运算放大器和高度匹配的薄膜电阻网络,具有非常高的CMRR(97dB),极低的增益误差0.0035% (35ppm)和极低增益漂移(1ppm/℃),主要用在高边或低边电流检测,双向宽共模电流检测,高压/低压电平转换,精密差分放大器,工业数据采集前端和绝缘电路替代件.本文介绍了LT6375主要特性,框图,多种应用电路,以及演示板DC2443评估电路,电路图,材料清单和PCB设计图。

　　The LT6375 is a unity-gain difference amplifier whichcombines excellent DC precision, a very high input commonmode range and a wide supply voltage range. It includes aprecision op amp and a highly-matched thin film resistornetwork. It features excellent CMRR, extremely low gainerror and extremely low gain drift.

　　Comparing the LT6375 to existing difference amplifierswith high common mode voltage range, the selectableresistor divider ratios of the LT6375 offer superior systemperformance by allowing the user to achieve maximumSNR, precision and speed for a specific input commonmode voltage range.

　　The op amp at the core of the LT6375 has Over-The-Top®protected inputs which allow for robust operation in environmentswith unpredictable voltage conditions.

　　The LT6375 is specified over the –40℃ to 125℃ temperaturerange and is available in space-saving MSOP16and DFN14 packages.

　　LT6375主要特性:

　　±270V Common Mode Voltage Range

　　97dB Minimum CMRR (LT6375A)

　　0.0035% (35ppm) Maximum Gain Error (LT6375A)

　　1ppm/℃ Maximum Gain Error Drift

　　2ppm Maximum Gain Nonlinearity

　　Wide Supply Voltage Range: 3.3V to 50V

　　Rail-to-Rail Output

　　350μA Supply Current

　　Selectable Internal Resistor Divider Ratio

　　300μV Maximum Offset Voltage (LT6375A)

　　575kHz –3dB Bandwidth (Resistor Divider = 7)

　　375kHz –3dB Bandwidth (Resistor Divider = 20)

　　–40℃ to 125℃ Specified Temperature Range

　　Low Power Shutdown: 20μA (DFN Package Only)

　　Space-Saving MSOP and DFN Packages

　　LT6375应用:

　　High Side or Low Side Current Sensing

　　Bidirectional Wide Common Mode Range Current Sensing

　　High Voltage to Low Voltage Level Translation

　　Precision Difference Amplifier

　　Industrial Data-Acquisition Front-Ends

　　Replacement for Isolation Circuits

　　图1.LT6375功能框图

　　图2.LT6375宽电压范围电流检测框图

　　图3.LT6375 2阶巴特沃斯滤波器输出滤波器图

　　图4.LT6375电流测量框图

　　图5.LT6375通信电源监测框图

　　图6.LT6375 27dB音频增益电路图

　　图7. LT6375 +/-5mAhowland(差分电压/电流转换电路)电流源电流源

　　图8. LT6375精密基准电压分压器/缓冲器电路

　　演示板DC2443

　　Demonstration Circuit 2443 is a Configurable High Voltage Amplifier featuring the LT®6375.

　　This demo board translates a high common mode signal to an output related to a low voltage reference level. The demo circuit is equipped with jumpers to facilitate set­ting the pin-strapped internal divider ratio configuration. The LT6375 is unique in that it may be powered from a low voltage (down to 3.3V) while it accepts signals well outside the supply range. This device is also unusual in that it can operate with high supply voltages (up to 50V). Connection points are provided to wire the amplifier in other configurations besides the simple translator.

　　图9.演示板DC2443评估测试图