UC3853 Datasheet | Unitrode

FEATURES - plete 8-pin Power Factor Solution - Reduced External ponents - RMS Line Voltage pensation - Precision Multiplier/Squarer/Divider - Internal 75k Hz Synchronizable Oscillator - Average Current Mode PWM Control - Overvoltage Protection parator - High Current, Clamped Gate Driver DESCRIPTION The UC3853 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 ponent 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 pensation. 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 75k Hz oscillator includes an external clock input, allowing synchronization to downstream converters. Additionally, the device features an overvoltage protection parator, a clamped MOSFET gate driver which self-biases low during undervoltage lockout, and low startup and supply current. These devices are available in 8-pin plastic and ceramic dual in-line (DIP) packages, and 8-lead small outline (SOIC) packages. The UC1853 is specified for operation from - 55°C to +125°C, the UC2853 is specified for operation from - 25°C to +85°C, and the UC3853 is specified for operation from 0°C to +70°C. BLOCK DIAGRAM 11/97 UDG-94120-1 ABSOLUTE MAXIMUM RATINGS Supply Voltage (VCC) - - - - - . . . . 40V Output Drive Current, Continuous - - - - - - . . 0.125A Peak - - - - - - - . . . . 0.5A Output Minimum Voltage - - - - - - 0.3V IAC Maximum Input Current - . ....