(1) MOSFET is a voltage-manipulating element, while transistor is a current-manipulating element. In the driving ability is not available, drive current is very small, should be selected MOSFET; and in the signal voltage is low, and promised to take more current from the electric fishing machine drive stage conditions, should be selected transistor.
(2) MOSFET is the use of most carriers conductive, so called unipolar device, while the transistor is that there is a majority of carriers, but also the use of a small number of carriers conductive. It is called bipolar device.
(3) Some MOSFET source and drain can be exchanged for the use of the gate voltage can be positive or negative, the flexibility than the transistor is good.
(4) MOSFET can operate in a very small current and very low voltage conditions, and its production process can be very convenient to integrate many MOSFETs in a silicon chip, so MOSFETs in large-scale integrated circuits have been widely used.
(5) MOSFET has the advantages of high input impedance and low noise, so it is also widely used in a variety of electronic trap equipment. Especially with the field effect tube to do the whole electronic equipment input, output stage, can obtain the general transistor is difficult to reach the function.
(6) MOSFETs are divided into two categories: red junction type and insulated gate type, and their manipulation principles are the same.
In fact, the triode is cheaper and more convenient to use, commonly used in the old low-frequency fishers, MOSFET for high-frequency high-speed circuits, high-current occasions, so the new type of high-frequency ultrasonic fishers, essential is the big MOS. generally speaking, low-cost occasions, the general use of the first to consider the use of transistors, not if you want to consider the MOS.
MOSFET is breakdown reasons and solutions are as follows
First, the input resistance of the MOSFET itself is very high, and the gate - source inter-electrode capacitance is very small, so it is very susceptible to external electromagnetic fields or electrostatic inductance and charged, and a small amount of charge can be formed in the inter-electrode capacitance of the appropriately high voltage (U = Q / C), will be damaged tube. Although the MOS input of the electric fishing machine has anti-static maintenance measures, but still need to be treated with care, in the storage and delivery of the best metal containers or conductive materials packaging, do not put in easy to attack static high voltage chemical materials or chemical fiber fabrics. Assembly, commissioning, things, appearance, workstation, etc. should be outstanding grounding. To avoid the operator's electrostatic interference damage, such as should not wear nylon, chemical fiber clothing, hand or something before touching the integrated block is best to connect the ground. To the equipment lead straightening and bending or manual welding, the use of equipment is necessary to outstanding grounding.
Second, the maintenance diode at the input of the MOSFET circuit, its on-time current tolerance is generally 1mA in the possibility of excessive transient input current (beyond 10mA), should be connected to the input maintenance resistor. And 129 # in the initial design did not participate in the maintenance resistor, so this is the reason why the MOSFET may breakdown, and by replacing an internal maintenance resistor MOSFET should be able to avoid the onset of such failure. And because the maintenance circuit to absorb the momentary energy is limited, too large a momentary signal and too high electrostatic voltage will make the maintenance circuit to lose effect. So when welding soldering iron is necessary to firmly grounded to prevent leakage breakdown equipment input, general use, can be powered off after the use of the residual heat of the soldering iron for welding, and first weld its grounded pins.
Post time: Jul-31-2024
