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Recognition and Measurement of Electronic Components
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This lesson mainly explains the polarity and function of the MOS tube
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Field effect transistors are referred to as field tubes for short,
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and are identified by the letter Q
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In the schematic diagram, the transistors will also use Q to identify
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Because there is no triode in the mainboard of the mobile phone,
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the triode is integrated inside the chip
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Therefore, in the mobile phone drawings,
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Q means MOS tube
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The MOS tube is a voltage control element,
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which uses the input voltage to control the output current
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MOS tubes are mainly divided into junction field effect transistors
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and insulated gate field effect transistors
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They will vary in their conductive properties
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Most of the mainboards use insulated gate enhanced field effect transistors
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This kind of MOS tube is widely used in the circuits
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Insulated gate field effect transistor is also called metal oxide semiconductor field effect transistor,
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referred to as MOS tube
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According to the different flow directions of MOS tube,
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it is divided into N-channel and P-channel
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In the mobile phone mainboard,
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there are N-channel MOS tubes and P-channel MOS tubes
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A MOS tube has 3 polarities, namely G, D, S
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The G pole is also called the control pole
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D is extremely drain, also called input pole
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The S pole is the source, also called the output
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We can compare the MOS tube to a faucet
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The D pole refers to the place where the faucet is connected to the water plant
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The G pole refers to the place where the valve controls the discharge of water
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The S pole is where the water comes out
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In real objects, the polarity of the MOS tube is not easy to distinguish
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The MOS tube used in the mainboard,
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generally the left side is the G pole,
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the upper side is the D pole,
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and the lower side is the S pole
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The MOS tubes used in laptops, some of which have 8 legs are single MOS tubes,
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and some are double MOS tubes,
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so the polarity is more difficult to distinguish
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Like this, we need to use the schematic diagram to identify
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The MOS tube in the mobile phone is not easy to distinguish in kind
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The MOS tube of the iPhone is in the shape of BGA,
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and there are no external pins
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MOS tube mainly plays the role of signal conversion and current conversion in mobile phones
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The relatively large MOS tube in the mobile phone
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is generally used in the charging circuit
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The MOS tubes used in other signal circuits are relatively small
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Ok, that's it for this lesson
