Design And Application Guide For High Speed MOSFET Gate Drive Circuits By Laszlo Balogh ABSTRACT The main purpose of this paper is to demonstrate a systematic approach to design high performance gate drive circuits for high speed switching applications. It is an informative collection of topics offering.

MOSFETs are widely used in switching power supplies due to their low internal resistance and fast switching speed. The MOSFET often selects a appropriate driver circuit based on the parameters of the power-supply IC and MOSFET. Let's discuss the drive circuits of MOSFETs for switching power supplies. When using a MOSFET to design a switching power supply, most people will consider the parameters of on-resistance, maximum voltage and maximum current of the MOSFET. But that's it.

We always only taking these factors into consideration. Such a circuit designed in this way is far from being a good circuit. We should take a closer look at its own parasitic parameters. Autobag hs 100 excel manual page.

For a certain MOSFET, its drive circuit, the peak output drive current, the rising rate and etc. Will all affect the switching performance of MOSFET. How MOSFETs and Field-Effect Transistors Work! When the power-supply IC and MOS transistor are selected, it is especially important to select an appropriate driver circuit to connect the IC to the transistor. A good MOSFET driver circuit has the following requirements: • (1) When the switching transistor is turned on, the drive circuit should be able to provide a large enough charging current to rapidly increase the voltage between the gate and source terminals of the MOSFET to the required value, ensuring that not only the switching transistor can be quickly turned on but also there is no high-frequency oscillation on the rising edge. • (2) During the on-time of the switch, the driver circuit can ensure that the voltage between the gate and source terminals of the MOSFET remains stable and reliably turned on.

• (3) At the moment of turn-off, the driver circuit can provide a path with as low impedance as possible to quickly discharge the capacitor's voltage between the gate and source terminals of the MOSFET, ensuring that the switch can be quickly turned off. • (4) The circuit structure should be simple, efficient and reliable. • (5) Electrical isolation is applied accordingly.

The MOSFET drive circuits commonly used in several power supply modules are described below. • The power-supply IC directly drives the MOSFET Figure 1 The power-supply IC directly drives the MOSFET The direct drive of power-supply IC is the most common and the simplest driving method. With this method, we should pay attention to several parameters and the influence of them.

First, check the power-supply IC manual to learn the maximum peak drive current allowed, because different IC chips have different drive capability. Second, check the parasitic capacitance of MOSFET, such as C 1, C 2 in figure 1. If the values of C 1 and C 2 are relatively large, the energy required to turn on the MOS transistor is relatively large either. If the power-supply IC does not have a adequate peak drive current, the transistor will be turned on at a slower speed.