What are the practical applications of MOS tubes?

Last Update Time: 2019-12-07 11:16:04

      This article describes the characteristics of the MOS tubes.

      MOS tubes are often used in hardware design. The following are N-type MOS tubes, including gate G, source S, and drain D.


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       The circuit symbols of the P-type MOS tube are as follows:


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      The MOS tube is similar to the triode except that the MOS tube is a voltage controlled type (voltage control) and the triode is a current controlled type (current control).

      As for the use of MOS tubes, there is a difference between N type and P type. For applications, we only need to know:

      1. For P-type MOS transistors, if G and S are high (voltage direction S points to G, the specific level looks at the specific MOS tube), D and S will be turned on (voltage direction S points to D), this When D and S are equivalent to a small resistance, if G and S are low (the specific level depends on the specific MOS tube), D and S will be cut off. At this time, D and S are equivalent to one very With a large resistance, current cannot flow.

      2. For N-type MOS transistors, if G and S are high (voltage direction G points to S, the specific level looks at the specific MOS tube), D, S (voltage direction D points to S) will be turned on, this When D and S are equivalent to a small resistance, if G and S are low (the specific level depends on the specific MOS tube), D and S will be cut off. At this time, D and S are equivalent to one very With a large resistance, current cannot flow.

      N-type MOS tube applications have more scenarios, compared to P-type MOS tubes, the advantages are as follows:

       1, the current passed is greater

       2, the switch speed is faster

       3, higher pressure resistance

      The following is a simple reference circuit of the N-type MOS tube. When the G terminal is turned into a high level, the MOS tube D and S are turned on. At this time, the MOS tube is turned on, the current of the motor is passed, and the motor rotates. When the G terminal is low, the D and S cannot be turned on, and the motor cannot run.


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     Practical application of MOS tube

     Before applying the MOS tube, after understanding the specific meaning of each parameter of the MOS tube, pay extra attention to the body diode of the tube itself, Vf=1.6V, after the conduction the impedance of the tube itself is generally mΩ; the tube often works in the following three State: Conduction, cut-off and variable resistance regions (there is also a linear amplification region).

     1. For logical conversion

     In addition to the level conversion of the signal, the level logic level conversion is often required, and the MOS tube and the triode can be realized. The following is the way of the MOS tube;


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     2. Slow start

     When there is a large capacitive load, such as electrolytic capacitors and high-power equipment power supplies (electric machinery, motor, etc.) need to be designed for slow start of the power supply, otherwise there will be a large surge current, the power supply voltage drops causing the system to reset, repeated restarts, etc. defect.


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      3. Used as a switch tube

      As the electronic switch control power supply is turned on and off, generally the positive electrode uses a PMOS tube, and the negative electrode is controlled by an NMOS tube;


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     4. For level conversion

     In circuit design, digital signals are inevitably required between different subsystems. The digital interface levels are often inconsistent between different systems or between devices. Therefore, level conversion circuits are required, and there are specially integrated ICs. Level conversion can be implemented from the perspective of cost saving. It can also be built with MOS tubes or triodes.

If you want to know more, our website has product specifications for MOS tubes, you can go to ALLICDATA ELECTRONICS LIMITED to get more information


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     Need to pay attention to the electrical level of the level, whether the external circuit level is determined, whether the two-way communication and communication rate affect the details of the specific circuit, the above is just a model.

     5. Anti-reverse use

     In the design of the power interface, there are many occasions to consider the problem of reverse connection. If there is no corresponding circuit design, it is easy to burn out the circuit and cause loss;

     The PMOS tube is usually used in the positive electrode, and the NMOS tube is usually used in the negative electrode; the upper circuit is only a model, and the specific circuit needs to increase the corresponding resistance of the container.

     There are many other uses for MOS tubes in the circuit.

     In particular, in the design of high-power circuits, it is necessary to understand the actual meaning and correlation of various parameters to avoid serious consequences.

If you want to know more, our website has product specifications for MOS tubes, you can go to ALLICDATA ELECTRONICS LIMITED to get more information