UC1853
UC2853
UC3853 High Power Factor Preregulator
FEATURES Complete 8-pin Power Factor
Solution Reduced External Components RMS Line Voltage Compensation Precision Multiplier/Squarer/Divider Internal 75kHz Synchronizable
Oscillator Average Current Mode PWM
Control Overvoltage Protection Comparator 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 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.
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 0В°C to +70В°C. BLOCK DIAGRAM UDG-94120-1 11/97 UC1853
UC2853 …
