High-frequency power supplies often require high-speed, high-current drivers such as the UCCx732x family. A leading application is the needed to provide a high-power buffer stage between the PWM output of the control IC and the gates of the primary power MOSFET or IGBT switching devices. In other cases, the driver IC is used to drive the power-device gates through a drive transformer. Synchronous rectification supplies are also needed to simultaneously drive multiple devices which presents an extremely large load to the control circuitry.
Driver ICs are used when having the primary PWM regulator IC directly drive the switching devices for one or more reasons is not feasible. The PWMIC does not have the brute drive capability required for the intended switching MOSFET, limiting the switching performance in the application. In other cases there may be a desire to minimize the effect of high-frequency switching noise by placing the high current driver physically close to the load. Also, newer ICs that target the highest operating frequencies do not incorporate onboard gate drivers at all. Their PWM outputs are only intended to drive the high impedance input to a driver such as the UCCx732x. Finally, the control IC is under thermal stress due to power dissipation, and an external driver helps by moving the heat from the controller to an external package.