1 Features

1? Qualified for Automotive Applications

? Controls Boost Preregulator to Near-Unity Power

Factor

? Limits Line Distortion low?

World-Wide Line Operation

? Overvoltage Protection

? Accurate Power Limiting

? Average Current Mode Control

? Improved Noise Immunity

? Improved Feed-Forward Line Regulation

? Leading Edge Modulation

? 150-μA Typical Start-Up Current

? Low-Power BiCMOS Operation

? 12-V to 17-V Operation

? Frequency Range of 6 kHz to 220 kHz

2 Applications

? Automotive

3 Description

The UCC2818A-Q1 device provides all the functions

necessary for active power factor corrected

preregulators. The controller achieves near unity

power factor by shaping the ac input line current

waveform to correspond to that of the ac input line

voltage. Average current mode control maintains

stable, low distortion sinusoidal line current.

Designed in Texas Instrument’s BiCMOS process,

the UCC2818A-Q1 device offers new features such

as lower start-up current, lower power dissipation,

overvoltage protection, a shunt UVLO detect circuitry,

a leading-edge modulation technique to reduce ripple

current in the bulk capacitor and an improved, low?

offset (±2 mV) current amplifier to reduce distortion at light load conditions.

The UCC2818A-Q1 PFC controller is directly pin-for- pin compatible with the UCC2818 devices. Only the

output stage of UCC2818A-Q1 device has been

modified to allow use of a smaller external gate drive

resistor values. For some power supply designs where an adequately high enough gate drive resistor

can not be used, the UCC2818A-Q1 device offers a

more robust output stage at the cost of increasing the

internal gate resistances. The gate drive of the

UC2818A, however, remains strong at ±1.2 A of peak

current capability.

The UCC2818A-Q1 device is intended for

applications with a fixed supply (VCC). It is available in the 16-pin D package.