The UC3853N is a high-power Factor Pre-regulator provides simple, yet high performance active power factor correction. Using the same control technique as the UC1854, this 8-pin device exploits a simplified architecture and an internal oscillator to minimize external component count. The UC3853 incorporates a precision multiplier/squarer/divider circuit, voltage and current loop error amplifiers and a precision voltage reference to implement average current-mode control with RMS line voltage compensation. This control technique maintains constant loop gain with changes in input voltage, which minimizes input line current distortion over the worldwide input voltage range. The internal 75kHz oscillator includes an external clock input, allowing synchronization to downstream converters. Additionally, the device features an overvoltage protection comparator, a clamped MOSFET gate driver which self-biases low during undervoltage lockout and low startup and supply current.
