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Hello everyone, in this lesson we will learn about the body diode of the MOS tube

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The body diode of the MOS tube is also called a parasitic diode

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As shown in the figure, it is also reflected in the circuit symbol of the MOS tube

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This diode, its characteristics are the same as ordinary diodes

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It can be turned on when the positive voltage is more than 0.7 volts higher than the negative

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So, this introduces the first property of the body diode

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That is, no matter whether the MOS tube is turned on or off,

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as long as the positive voltage of the body diode is 0.7 volts greater than the negative, it can be turned on

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For example, an N-channel MOS tube

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When the G pole has a high level, the DS poles are turned on

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No matter from D to S, or from S to D, they are all conducting

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But when the G pole comes to a low level, the MOS tube is cut off

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There is no conduction between the D pole and the S pole.

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But because of the existence of the body diode,

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as long as the voltage of the S pole is greater than 0.7V of the D pole, the S and D poles can still be conductive

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Another characteristic of the body diode is that

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the current that can flow through the body diode is generally relatively small.

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At the same time, the body diode directions of N-channel MOS tubes and P-channel MOS tubes are different.

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The direction of the body diode of the N-channel MOS tube is from the S pole to the D pole

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The direction of the body diode of the P-channel MOS tube is that the D pole points to the S pole.