The High-Voltage Integrated Circuit (HVIC) gate driver family is designed to drive an N-channel MOSFET or IGBT up to 600 V. One of the most common methods to supply power to the high-side gate drive circuitry of the high-voltage gate drive IC is the bootstrap power supply. This bootstrap power supply technique has the advantage of being simple and low cost. However, duty cycle is limited by the requirement to charge the bootstrap capacitor and serious problems occur when extremely short pulse width is used in the application system. This application note explains the features of HVIC gate drivers and provides recommendations to avoid short pulse-width issues in the application.
In the HVIC gate driver block diagram shown in the Figure, a typical HVIC gate driver consists of input, pulse generator, level shifter, Under-Voltage Lockout (UVLO), control latch, and driver circuit. HVIC gate driver IC uses bootstrap method to control MOSFET and IGBT. By adding a bootstrap circuit outside the HVIC, the high side can be supplied with a signal power source. This kind of “floating supply” is suitable for providing gate drive circuitry to directly drive high-side switches that operate up to rail voltages.