Study And Design Of A High Precision Current Shunt Monitor With Wide Common Mode Input Voltage Range

Current sense technology is widely used in modern electronic information systems.Whether in system feedback control or circuit system protection,current sense technology has a very important position.According to specific R&D project requirements,based on the analysis of current sense circuit research background and research status at home and abroad,this paper proposes corresponding circuit solutions for the application environment and design difficulties of high-side current detection chips.Based on CR Shanghua's 80-120 V 0.18?m BCD high-voltage process technology,this paper designs a new type of wide-input common-mode voltage range high-precision current sense amplifier circuit with completely intellectual property rights,and carries on the design of the comprehensive and systematic simulation and verification.The current sense amplifier designed in this paper includes four main parts: power supply voltage conversion control,input stage,intermediate stage and output stage.In the input stage,this paper proposes a new type of level shifting and signal acquisition circuit,which can accurately collect high-voltage signals and shift the negative voltage signals to positive voltage.The level-shifted signals are sent to the first-stage amplifier.In order to obtain higher amplification accuracy,a gain bootstrap circuit is added to the amplifier module to increase the amplification factor to 142 d B,and a current feedback loop is introduced in the amplifier module to optimize the linearity of the amplifier.After the input stage collects and amplifies the signal,it is passed to the intermediate stage amplifier,that is,a typical three-op-amp instrumentation amplifier,which converts the differential signal into a single-ended signal and amplifies it again.A new swing optimization technique is used in the output stage amplifier to push the output swing to a range that is 0.2V lower than the power supply voltage.The simulation results show that the current sense amplifier designed in this paper can be applied to the common mode input voltage range of-16V?+80V.The system integrates a high input voltage low dropout linear regulator without external capacitors,which makes the system power supply voltage range extended to 2.7V?18V.The detection voltage range of the current sense amplifier is 10 m V?356m V,the amplification factor is 50V/V,the maximum allowable output voltage is 17.8V,the maximum gain error does not exceed 5%,and the operating temperature range is-40??125 ?.The overall circuit simulation shows that the wide common-mode input voltage range high-precision current sense circuit designed in this paper has achieved the expected function,and the main technical parameters have reached or exceeded the predetermined design index.