Therefore, switching currents are often required in the range of several hundred milliamperes, or even in the range of amperes. The switching time of a transistor is inversely proportional to the amount of current used to charge the gate.
Typical switching times are in the range of microseconds. Therefore, it is necessary to keep the switching time as short as possible, so as to minimize switching loss. Consequently, when gate current is applied to a transistor to cause it to switch, a certain amount of heat is generated which can, in some cases, be enough to destroy the transistor. When a transistor is switched on or off, it does not immediately switch from a non-conducting to a conducting state and may transiently support both a high voltage and conduct a high current. Similarly, to switch the transistor off, this charge must be dissipated, i.e. As a transistor requires a particular gate voltage in order to switch on, the gate capacitor must be charged to at least the required gate voltage for the transistor to be switched on. The isolated gate-electrode of the MOSFET forms a capacitor (gate capacitor), which must be charged or discharged each time the MOSFET is switched on or off. In contrast to bipolar transistors, MOSFETs do not require constant power input, as long as they are not being switched on or off.
#Half bridge mosfet driver ic drivers
The HVIC gate drivers with floating switches are well-suited for topologies requiring high-side, half-bridge, and three-phase configurations. With the ability to place high-voltage circuitry (in a ‘well’ formed by polysilicon rings), that can ‘float’ 600 V or 1200 V, on the same silicon away from the rest of the low-voltage circuitry, high-side power MOSFETs or IGBTs exist in many popular off-line circuit topologies such as buck, synchronous boost, half-bridge, full-bridge and three-phase. Using this mixed-signal HVIC technology, both high-voltage level-shifting circuits and low-voltage analog and digital circuits can be implemented. In 1989, International Rectifier (IR) introduced the first monolithic HVIC gate driver product, the high-voltage integrated circuit (HVIC) technology uses patented and proprietary monolithic structures integrating bipolar, CMOS, and lateral DMOS devices with breakdown voltages above 700 V and 1400 V for operating offset voltages of 600 V and 1200 V. An integrated gate-driver solution reduces design complexity, development time, bill of materials (BOM), and board space while improving reliability over discretely-implemented gate-drive solutions. A gate driver IC serves as the interface between control signals (digital or analog controllers) and power switches (IGBTs, MOSFETs, SiC MOSFETs, and GaN HEMTs). In essence, a gate driver consists of a level shifter in combination with an amplifier.
Gate drivers can be provided either on-chip or as a discrete module.
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