UCC2818A-Q1,pdf(BiCMOS Power F

The UCC2818A provides all the functions necessary for active power factor corrected preregulators. The controller achieves near unity power factor by shaping the ac input line current waveform to correspond to that of the ac input line voltage. Average current mode control maintains stable, low distortion sinusoidal line current.

Designed in Texas Instrument’s BiCMOS process, the UCC2818A offers new features such as lower start-up current, lower power dissipation, overvoltage protection, a shunt UVLO detect circuitry, a leading-edge modulation technique to reduce ripple current in the bulk capacitor and an improved, low-offset (±2 mV) current amplifier to reduce distortion at light load conditions.

The UCC2818A PFC controller is directly pin-for-pin compatible with the UCC2818 devices. Only the output stage of UCC2818A has been modified to allow use of a smaller external gate drive resistor values. For some power supply designs where an adequately high enough gate drive resistor can not be used, the UCC2818A offers a more robust output stage at the cost of increasing the internal gate resistances. The gate drive of the UC2818A, however, remains strong at ±1.2 A of peak current capability.

UCC2818A is intended for applications with a fixed supply (V_CC). It is available in the 16-pin D package.