In the power switch and other power supply system design program, program designers will pay more attention to a number of major parameters of the MOSFET, such as on-off resistor, larger operating voltage, larger power flow. Although this element is critical, taking into account the improper place will make the power supply circuit can not work properly, but in fact, this is only completed the first step, the MOSFET's own parasitic parameters is considered to be the important thing to jeopardize the power supply circuit.
Immediate driving of MOSFETs with power supply ICs
A good MOSFET driver circuit has the following provisions:
(1) The moment the switch is enabled, the driver circuit should be able to output a very large current, so that the MOSFET gate-source inter-pole operating voltage rises quickly to the required value, to ensure that the switch can be turned on quickly and there will be no high-frequency oscillations on the rising edge.
(2) power switch on and off period, the drive circuit can ensure that the MOSFET gate source inter-pole operating voltage is maintained for a long time, and effective conduction.
(3) Close a moment of the drive circuit, can supply a low impedance channel for the MOSFET gate source capacitance operating voltage between the rapid drain, to ensure that the switch can be quickly turned off.
(4) Simple and reliable construction of drive circuits with low wear and tear.
(5) According to the specific situation to carry out protection.
In the control module power supply, the most common is the power supply IC directly drive MOSFET. application, should pay attention to the larger drive the highest value of power flow, MOSFET distribution capacitance 2 main parameters. Power IC drive capability, MOS distribution capacitance size, drive resistor resistance value will jeopardize the MOSFET power switching rate. If the selection of MOSFET distribution capacitance is relatively large, the power supply IC internal drive capability is not enough, must be in the drive circuit to improve the drive capability, often apply the totem pole power supply circuit to enhance the power supply IC drive capability.
Post time: Jul-25-2024
