IC687RCM711B High Precision Operational Amplifiers

The current value of IC687RCM711B is too small, the output signal will be small during the test, in order to make the measured signal meet the requirements of A/D it is necessary to increase the amplification of the amplifier circuit, which increases the error of the system. Considering the above two reasons, the current value of the constant current source in this system is set at 0.5 mA. The constant current source circuit design uses the IC687RCM711B high-precision chopper stabilised zero operational amplifier [2] and voltage reference source TL431.

IC687RCM711B chopper-stabilised zero operation gives it excellent DC characteristics, out-of-phase voltage and its drift, common-mode voltage, and low-frequency noise, etc. The TL431 is a three-terminal adjustable voltage reference source with good thermal stability, and its output voltage can be set in the range of 2.5 V to 36 V. The TLC2652 is a high-precision chopper-stabilised operational amplifier [2] and the TLC2652 is a high-precision chopper-stabilised operational amplifier.

IC687RCM711B uses 32 eight-selective multi-switching device CD4051 and two 74LS138 to form an electronic switching array, which realises the control of 128 channels, and can select any one of 128 Pt resistors for testing. Measurement circuit measured by the Pt resistance sensor voltage at both ends of the amplifier circuit into the MSP430 microcontroller for A/D conversion.