The UCC2818A-Q1 device 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-Q1 device 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
The UCC2818A-Q1 PFC controller is directly pin-for-pin compatible with the UCC2818
devices. Only the output stage of UCC2818A-Q1 device 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-Q1 device 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.
The UCC2818A-Q1 device is intended for applications with a fixed supply
(VCC). It is available in the 16-pin D package.
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