SLG46583V Implementing MAF Sensor with GreenPAK
■Introduction
●What is MAF. Mass Air flow sensor is a commonly used sensor for injection engines. At the engine chambers, the fuel and air has been mixed to cause the required explosion to move the piston. The fuel air mix should be at the best performance ratio. If the fuel is higher than required ratio, then the engine is less efficient and causes low
utilization of fuel, leading to low performance and downgrading of the engine power. To inject fuel into engine, the ECU "Engine Control Unit" needs to know the exact amount of air entering the engine. In case of having the correct airflow, measurement will help the ECU to calculate the best amount of fuel to inject. The MAF solves this issue by giving the ECU the exact measurement of the air flow entering the engine chamber.
●The MAF sensor stays at the input of the air tube, blocking a portion of it to take a sample of air flow. The MAF uses a simple technique to measure the air flow by having a small path for the airflow sample. Inside this path, there is a small heater that is controlled such that it stays at the same temperature whatever the airflow is passing
through it. This is possible with the help of a simple PID controller that keeps the heater temperature constant. The controller measures the heater temperature during the feedback loop during which it rises/reduces the heater power to maintain the temperature at a certain point.
●By a simple calculation, if the heater temperature is constant as the controller changes its power in accordance to the change in airflow then the current passing through the heater represents the amount of air flow passing through the heater. It is a simple technique of blowing a hot surface(heater) will causes the heat to dissipate faster; the hot surface will require more power to become hot again if the airflow is continuing blowing it.
●Why this simple technique? The airflow in the engine doesn't change very fast. It doesn't require a very fast response sensor to measure the airflow, so an easy way out is to avoid using a very sophisticated sensor.
●Most of the MAF sensors in the market uses an ASIC chip to implement the sensor has budget constraints in engineering and upgrading. The ASIC takes months maybe years of work to get designed with no issues. Implementing this sensor with an FPGA will be a good idea but it is impossible to fit inside the sensor tiny chassis; GreenPAK is the best of two worlds to implement the sensor in a tiny board with much less engineering work.
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[ MAF Sensor ][ Mass Air flow sensor ] |
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Application note & Design Guide |
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Please see the document for details |
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English Chinese Chinese and English Japanese |
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Oct 21, 2022 |
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Rev.1.00 |
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R19AN0165EU0100 |
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855 KB |
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