FS9721_LP3 is a high performance, low power consumption and 3 3 /4 digits (4000 Counts) Analog to Digital Converter that built-in the microprocessor (ADC+MCU). It includes the 8 bits microprocessor, low noise and high stability OPAMP, AC rectifier OPAMP, voltage promotion and regulated voltage power, high regulated bandgap, auto measurement switch and function control circuit, buzzer driver circuit, clock oscillation circuit, backlight display control circuit, LCD display driver circuit and so on. With the microprocessor, FS9721_LP3 can process the logic function control via I/O ports, and through the codes of MEA1〜MEA4 pins, it can assemble various measurement functions, as well as construct fully auto measurement meter through the code settings. For the settings of Range, Select, Hold, Rel, BLCTR, Hz/Duty and Reset keys, it can be fulfilled the measurement mode select, function switch, reading hold, relative value measurement, backlight display, frequency and duty cycle measurement, reset and so on functions by triggering these keys. FS9721_LP3 has the serial data output function so that users can connect the meter and the equipment of computer for recording, analyzing, processing and printing the measuring data. With regard to the auto power off function, when there is no action within 30 minutes on the switch or keys of the meter, the system will enter the sleep mode automatically to save the power. In the process of using the meter, if it is not necessary to power off automatically, the function can also be cancelled in use. FS9721_LP3 is made by large integrated circuit technology so that rise greatly up the reliability of the product, and make the design be simple and the volume be small. It takes low power voltage so as to be low power consumption and is convenient to use the power supply of battery, especially is proper for the use on the palm mode meter. FS9721_LP3 is a microprocessor-embedded and multifunctional measuring ADC so that just less external components added, it can be a high accuracy, lots functions and low cost measuring meter.