- HIH CURENT TOTEM POLE OUTPUT DRIVERS
- HIH CURENT TOTEM POLE OUTPUT DRIVER
- HIH CURENT TOTEM POLE OUTPUT MANUAL
The power-supply IC drive capability is insufficient. If the drive capability is insufficient, high-frequency oscillations may occur on the rising edge, even if Rg in Figure 1 is reduced, the problem cannot be solved! And IC drive capability, MOSFET parasitic capacitance, MOSFET switching speed and other factors may also affect the choice of drive resistance, so Rg can not be reduced indefinitely.Ģ. If the power-supply IC does not have a adequate peak drive current, the transistor will be turned on at a slower speed. 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. Second, check the parasitic capacitance of MOSFET, such as C 1, C 2 in figure 1.
HIH CURENT TOTEM POLE OUTPUT MANUAL
With this method, we should pay attention to several parameters and the influence of them.įirst, check the power-supply IC manual to learn the maximum peak drive current allowed, because different IC chips have different drive capability. The direct drive of power-supply IC is the most common and the simplest driving method.
The power-supply IC directly drives the MOSFET The power-supply IC directly drives the MOSFET.įigure 1. The MOSFET drive circuits commonly used in several power supply modules are described below.ġ. Electrical isolation is applied accordingly. The circuit structure should be simple, efficient and reliable.ĥ.
HIH CURENT TOTEM POLE OUTPUT DRIVER
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.Ĥ. 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.ģ. 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.Ģ. 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.Ī good MOSFET driver circuit has the following requirements:ġ. How MOSFETs and Field-Effect Transistors Work! will all affect the switching performance of MOSFET. For a certain MOSFET, its drive circuit, the peak output drive current, the rising rate and etc. We should take a closer look at its own parasitic parameters. Such a circuit designed in this way is far from being a good circuit. We always only taking these factors into consideration. 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. Let's discuss the drive circuits of MOSFETs for switching power supplies. The MOSFET often selects a appropriate driver circuit based on the parameters of the power-supply IC and MOSFET. MOSFET s are widely used in switching power supplies due to their low internal resistance and fast switching speed.
HIH CURENT TOTEM POLE OUTPUT DRIVERS
Topics covered in the book include the state-of-the-art of power MOSFET drive techniques, the switching loss model, current source gate drivers (CSDs), resonant gate drivers, adaptive gate drivers and GaN HEMT gate drivers. If the parasitic capacitance of the selected MOS transistor is large and the driving capacity of the power-supply IC is insufficient, the totem pole circuit is often used to enhance the drive capability of the power supply IC, which is shown in the dotted box of figure 2.
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.
The author perfected the content of this article on December 26th
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