The MC44603 is an enhanced high performance controller designed for off-line DC-DC converter applications. This device has the unique ability to automatically change the operating mode if the converter output is overloaded, unloaded, or short-circuited, providing the designer with additional protection and improving system reliability. The MC44603 has several notable features when compared to conventional switching power controllers. These features include a foldback facility for overload protection, standby mode when the converter output is slightly loaded, reduced switching transistor stress, demagnetization detection diodes and a high current totem pole output ideal for driving power MOSFETs. It can also be used to drive bipolar transistor converters at low power (<150 watts). This is optimized to work in continuous mode, but can also work in continuous mode. Its advanced design allows applications using current mode or voltage mode control.

Current or voltage mode controller • Operates up to 250 kHz switching frequency • Inherent feed-forward compensation • Cycle-by-cycle current limit locked to PWM period • Accurate frequency controlled oscillator

High flexibility • Externally programmable reference current • Secondary or primary sensing • Synchronization mechanism • High current totem pole output • Undervoltage lockout safety/protection with hysteresis • Overvoltage protection against open current and open voltage loops • Oscillator Pin Short-Circuit Protection • Fully Programmable Foldback • Soft-Start Capability • Accurate Maximum Duty Cycle Setting • Demagnetization (Zero Current Detect) Protection • Internal Trim Reference