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Hello everyone, in this lesson we will learn the measurement of MOS tubes
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First of all, we need to know why we need to measure the MOS tube
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Because there is no difference in the appearance of the two MOS tubes
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In the absence of a circuit diagram, we can only judge the type of MOS tube by measurement
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And through measurement, we can also judge whether the MOS tube is good or bad.
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Let's first take a look at the method of judging the type of MOS tube by measurement
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Judging the type of MOS tube is actually judging the direction of the body diode inside the MOS tube
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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.
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When we measure N-channel MOS tubes, put the red marker on the S pole,
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and the black marker on the D pole.
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At this time, the body diode can be turned on, and the value can be measured
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The other connection methods can not measure the value
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For P-channel MOS tubes, only when the red marker is placed on the D pole
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and the black marker is placed on the S pole,
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the body diode inside the MOS tube can be turned on, and the value can be measured.
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The other connection methods can not measure the value
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It should be noted that the measurement methods we are talking about here are all offline measurements,
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that is, dismantled and measured
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When online measurement, other connection methods can generally also measure the value,
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but the measured value will be far greater than the normal measured value
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Next, let's measure it in real
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Here we have prepared two MOS tubes
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Let's judge the types of these two MOS tubes
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First we need to adjust the multimeter to the diode file
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In order to facilitate the measurement, we turned the MOS tube over
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Let's first measure the MOS tube on the left
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The red marker is connected to the D pole, and the black marker is connected to the S pole.
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It can be seen that the measured value is 203
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Connect the black marker pen to the D pole, and the red marker pen to the S pole
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The measured value is OL
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It shows that the direction of the body diode inside the MOS tube is from the D pole to the S pole
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Then this MOS tube is a P-channel MOS tube
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Next, let's measure the MOS tube on the right
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The measurement method is still the same,
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connect the red marker to the D pole, and the black marker to the S pole
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It can be seen that the measured value is OL
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Next, we put the red marker on the S pole and the black marker on the D pole.
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It can be seen that the measured value is 531
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It shows that the direction of the body diode inside the MOS tube is from the S pole to the D pole
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Therefore, this MOS tube is an N-channel MOS tube
