| 摘要 |
PURPOSE: A mass flow controller using an analog gain control and an operating method thereof are provided to process plural flow ranges and plural kinds of gases by controlling the analog gain and using a scale factor. CONSTITUTION: A mass flow controller using an analog gain control includes a sensor, a bypass, a valve, and a control circuit(140). The control circuit includes an interface unit, a microprocessor, a multiplexer, a resistor unit, and an amplifier unit. The interface unit(141) outputs data about flow ranges and kinds of gases to the microprocessor. The microprocessor(142) is used for selecting a particular resistor according to the output data of the interface unit, outputting a switching control signal to the multiplexer, performing a scale control process, calculating the flow of mass, and outputting a valve control signal to a valve. The multiplexer(143) is used for switching the particular resistor according to the switching control signal of the microprocessor. The resistor unit(144) is formed with a plurality of resistors having different analog gain values. The amplifier unit(145) amplifies a variation of temperature according to the analog gain of the particular resistor.
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