The UC2853A 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 UC2853A 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 63kHz 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.

The UC2853A is identical to the UC2853 except the internal oscillator frequency has been reduced from 75kHz to 63kHz. The switching frequency is lowered in order to keep the second harmonic of the switching frequency below a 150kHz. For EMI specifications at 150kHz this makes it easier for a design to meet system requirements.Read more