What is the difference between using a MOS tube switch alone and a triode with a MOS tube as a switch?
Sammy Posted on January 4, 2021
Level conversion and isolation protection. It does not matter if the voltage is small.
Franco Posted on January 4, 2021
The general IO of ARM and MCU is more than 3.3V. If you control the voltage of 12V, 24V, without the cooperation of the triode, a single MOS tube can't do it. If the CPU side is broken, adding a transistor would be much better. So it's not that MOS can't be used, it depends on the situation.
Melinda Posted on January 4, 2021
The P-type MOS tube is used as the power switch. If there is no triode OC gate to cooperate, you need to pay attention to several things:
The gate control level must not be lower than the controlled power supply, and the P-type MOS transistor Vgs >= Vds will be turned off. If you use 1.8V to directly control P-type MOS transistors to switch 3.3V, there will usually be problems that cannot be dropped.
Before the IC is powered off, the pins may not have high impedance. The controlled power supply may leak into the IC through the control pins, which may cause malfunctions or burn out. This problem has occurred in many cases.
The gate control signal usually comes from the microcontroller (MCU), the pin status is uncertain before the reset (Reset) is completed, the moment the system is powered on may cause the power to turn on briefly, which may cause system malfunction or malfunction, such as The light or the screen backlight flashes, the motor rotates, etc.
Chace Posted on January 4, 2021
The triode acts as a current-voltage conversion. After all, the characteristics of the two tubes are different.
