For domestic MOS, choose TMC-2 -- Application of DC brushless motor controller
➡ PMOS anti-reverse power connection circuit:
When the power is first turned on, the body diode of PMOS Q1 conducts. At this time, Vs > Vg, the PMOS tube turns on. After the PMOS conducts, it shorts the body diode, and the power supply works normally.
If the positive and negative poles of the power supply are reversed, the PMOS turns off and the body diode of the PMOS is also in reverse connection and does not conduct, thus playing a protective role.
Among them, D1 is a Zener diode to prevent Vcc > 12V from exceeding the limit value of Vg and causing breakdown, so as to protect the G pole.
➡ PMOS switch circuit:
Generally, the PMOS switch is on the high side, that is, the power supply end, and the NMOS switch is on the low side, that is, the GND end or the negative power supply end. When the power is first turned on, R2 makes Ug = Us, so it is cut off at this time, and the back end is not powered on. It is necessary to pull down Ug through CONTROL so that Ug < Us, the MOS tube conducts, and the back end is powered on. This process plays a role in switch control. Of course, the MOS itself has an on-resistance Rds. If it is used in high-current applications, a voltage drop will be generated. At this time, it is necessary to consider selecting a MOS tube with a smaller Rds, such as: TM80P03D. Of course, the junction temperature Tj of the device itself should also be considered, and good heat dissipation should be done.
If the CONTROL terminal cannot reach VCC, or VCC has exceeded its limit value, then the following circuit can be considered, using an NMOS or triode to drive to avoid burning the CONTROL terminal.
➡ PMOS anti-backflow circuit:
First of all, it should be clear that anti-reverse connection and anti-backflow are two different things. This circuit realizes anti-backflow through two back-to-back PMOS. When CONTROL is at a high level, the NMOS of Q3 is turned on, the G poles of Q1 and Q2 are pulled down, and after Q1 is turned on, Q2 is also turned on, and the circuit is powered on. When CONTROL is at a low level, Q3 is turned off, Ug = Us of Q1 and Q2 is cut off, and the circuit is turned off. At this time, the body diode of Q1 is in reverse connection, which plays the role of anti-backflow.
Practical cases of MOS tubes:
➡ 1、Electric scooter: TM50N06D (3 pieces) + TM50P06D (3 pieces), main power switch: TM100P06D
➡ 2、High-power vacuum cleaner: TM50N06D (3 pieces) + TM50P06D (3 pieces), main power switch: TM100P06D
➡ 3、Sweeping robot: TM35G06NF (3 pieces) or TM20G06GD (3 pieces), main power switch: TM60P06D
The above three pictures are the actual PCBA of the electric scooter, the actual PCBA of the high-power vacuum cleaner and the PCBA of the sweeping robot respectively. It can be seen that MOS tubes are important components of the inverter bridge in high-power brushless motor applications and are widely used.
Among them, the main brushless motor needs to be driven by a three-phase inverter bridge. Now, small-power motor manufacturers will choose the integrated scheme of inverter bridge + driver chip, but high-power brushless motors still use the traditional external three-phase inverter bridge. It is composed of 6 high-power MOS, and the current commutation function of the brushless motor is completed through the control of the driver chip. Recommended models: TMC 的 TM50N06D， TM50P06D。
To sum up, as a key component in circuit design, MOSFET, with its excellent characteristics and wide applicability, plays an indispensable role in power electronics, brushless motor control and other fields. Through in-depth understanding of its working principle and parameters, combined with the practice of various circuit applications, engineers can use its advantages more flexibly and efficiently to build safe and reliable circuit systems. In the context of the rapid development of modern electronic technology, MOSFET is not only a component, but also a door to a new world of innovation and efficiency. In the future, with the continuous improvement of process and design levels, MOSFET will shine in more emerging fields, providing solid technical support for our daily life and the progress of various industries.
Taimei Semiconductor is deeply engaged in MOSFET technology, committed to the progress and innovation of MOSFET in various power applications, growing together with engineers, accompanying engineers on the road of exploring and learning MOSFET application technology, and exploring more potential of MOSFET!
