FEATURES
• Complete 8-pin Power Factor
Solution
• Reduced External Components
• RMS Line Voltage Compensation
• Precision Multiplier/Squarer/Divider
• Internal 63kHz Synchronizable
Oscillator
• Average Current Mode PWM
Control
• Overvoltage Protection Comparator
• High Current, Clamped Gate Driver

DESCRIPTION
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.
These devices are available in 8-pin PDIP (P) and SOIC (D) packages. The
UC2853A is specified for operation from –40°C to 105°C.