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Hello everyone, in this lesson we will learn the common high level and low level in the circuit

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Before understanding high level and low level, we need to understand digital circuits

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When devices such as computers and mobile phones process signals, they are all digital

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In digital circuits, there are only two concepts of 0 and 1.

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High level and low level correspond to the two concepts of 1 and 0 respectively

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High level represents 1, low level represents 0

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At the same time, the high level can be expressed by high/H, and the low level can be expressed by Low/L

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When understanding high level and low level, we can say that high level is high voltage and low level is low voltage

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And how high the voltage is to be considered a high level, and how low is the voltage to be considered a low level?

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We need to know that their voltages are not fixed, but relative.

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We need to combine the whole circuit to analyze

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For example, the two MOS tubes on the right

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The N-channel MOS tube is turned on at high level

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That is, the G-pole voltage is greater than the S-pole voltage of 4.5V or more before it can be fully turned on.

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Assuming that the S-pole voltage is 5V, then the G pole voltage will be high when it is above 9.5V

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The P-channel MOS tube is turned on when the low level

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That is, when the G-pole voltage is lower than the S-pole 4.5V, it can be turned on

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When the S pole voltage is 5V, the G pole is low only when the G pole is below 0.5V

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It can be seen from this that the high level and low level of a voltage are affected by the circuit

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However, in most cases, 0V represents a low level and 3V represents a high level.