What are the precautions for using MOS tubes?
The MOS transistor is electrically conductive by a majority of carriers, also called a unipolar transistor. It belongs to a voltage controlled semiconductor device. It has high input resistance (10^7~10^12Ω), low noise, low power consumption, large dynamic range, easy integration, no secondary breakdown, wide safe working area, etc. It has become a powerful competitor of bipolar transistor and power transistors.
All MOS integrated circuits (including P-channel MOS, N-channel MOS, complementary MOS-CMOS integrated circuits) have an insulated gate to prevent voltage breakdown. The thickness of the insulating gate oxide layer of a typical device is approximately 25 nm, 50 nm, and 80 nm. In addition to the high-impedance gate of the integrated circuit, there is a resistor-diode network for protection. However, the protection network inside the device is not enough to avoid electrostatic damage (ESD) to the device. Experiments indicate that the device will fail during high-voltage discharge. The device may also fail for the accumulation of multiple lower voltage discharges. According to the severity of the damage, there are many forms of electrostatic damage. The most serious and most likely to occur is the complete destruction of the input or output so as to be short-circuited or open to the power supply VDD GND, and the device completely loses its original function. A little bit of serious damage is intermittent failure or degradation of performance, which is even more difficult to detect. There are also some electrostatic damage that can cause the device performance to deteriorate due to increased leakage current.
Some considerations for MOS tube applications
MOS tube is a voltage-driven high-current type device, which is widely used in circuits, especially power systems. MOS tubes have some characteristics that should be paid special attention in practical applications.
1. The MOS tube is non-directional after being turned on. After the MOS is turned on, it is similar to a wire. It has only resistance characteristics and no conduction voltage drop. Generally, the saturation on-resistance is several to several tens of milliohms. And no directionality, allowing direct current and alternating current to pass.
2, MOS tube body diode, also known as parasitic diode, in a single MOS tube device, not in integrated circuit lithography, this diode can play the role of reverse protection and freewheeling in high current drive and inductive load Generally, the forward voltage drop is about 0.7-1V. Because of the existence of this diode, the MOS device cannot simply see the function of a switch in the circuit. For example, in the charging circuit, after the charging is completed, the battery will be reversed after the power is removed. To supply power to the outside, this is usually the result we don't want to see. The general solution is to add a diode to prevent reverse power supply. This can be done, but the characteristics of the diode must be 0.6-1V. To the pressure drop, in the case of high current, the heat is severe, and at the same time, the energy is wasted, and the energy efficiency of the whole machine is lowered. Another method is to add a back-to-back MOS tube and use the low on-resistance of the MOS tube to achieve energy saving. Another common application of this characteristic is low-voltage synchronous rectification.
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