What is the use of the resistance between the DC power MOS tubes GS?
The actual function of connecting the resistance between the DC power MOS tubes GS lies in the drive circuit of the DC power MOS tubes GS. This resistance may or may not exist. Common values are 5k and 10k, but what is the purpose of this resistor?
Find the DC MOS tube, hover over G, and add voltage to DS. What will the result be? If the input voltage is only a few tens of volts, the lamp is on and the lamp is burned out.
Why is the MOS tube turned on without adding a driving signal? This is because there is a capacitance between DG and GS and Cdg and Cgs in the tube. Therefore, the voltage applied between DS charges Cgs through Cdg. Incidentally, the voltage of the G pole rises until the MOS transistor of the DC power supply is turned on.
Therefore, when the DC power drive circuit does not work and there is no discharge circuit, the MOS tube of the DC power supply is fragile, and when the transformer is used to drive, the transformer winding has a discharge function, even if no DC resistance is added to the driver, the tube will not conduct electricity. Pass. Summary 1. The damage of static electricity to the DC power MOS (please refer to the reason: Since the junction capacitance of the equation U = Q/C is small, when the voltage is high, the smaller Q will also generate a voltage, and the DC power MOS tube will be damaged ) 2. Provide fixed offset.
When the bias circuit is disconnected, this small resistor effectively turns off the DC power supply MOS (reason: G pole is disconnected, when a voltage is applied to the DS port, Cgd is charged and the G terminal voltage rises, which cannot be effectively turned off) 3 , Explain the size of the resistor. If it is too small, the drive current and drive force will increase. If it is too large, the resistance will increase, and the off-time of the DC power MOS tube will be longer.
