LINEAR TECHNOLOGY LT1248 Power Factor Controller Specifications Data Sheet

LT1248

Power Factor Controller

FEATURES DESCRIPTIO

High Power Factor Over Wide Load Range The LT®1248 provides active power factor correction for with Line Current Averaging universal off-line power systems. By using fixed high International Operation Without Switches frequency PWM current averaging, without the need for Instantaneous Overvoltage Protection slope compensation, the LT1248 achieves far lower line Minimal Line Current Dead Zone current distortion with a smaller magnetic element than Typical 250µA Start-Up Supply Current systems that use either peak-current detection or zero Rejects Line Switching Noise current switching approaches in both continuous and Synchronization Capability discontinuous modes of operation.

Low Quiescent Current: 9m A

The LT1248 uses a multiplier containing a square gain

Fast 1.5A Peak Current Gate Driver

function from the voltage amplifier to reduce the AC gain at light output load and thus maintains low line current APPLICATIO S distortion and high system stability. The LT1248 also provides filtering capability to reject line switching noise

Universal Power Factor Corrected Power Supplies

which can cause instability when fed into the multiplier.

Preregulators Up To 1500W

Line current dead zone is minimized with low bias voltage at the current input to the multiplier. The LT1248 provides many protection features including peak current limiting and overvoltage protection, and can be operated at frequencies as high as 300k Hz. , LTC and LT are registered trademarks of Linear Technology Corporation.

BLOCK DIAGRA

VAOUT VREF MOUT ISENSE CAOUT PKLIM GND VCC

7.5V VCC VREF

16V TO 10V

2.6V/ EN/SYNC 2.2V 7µA

VSENSE

EA 2 IB IM

IAC 32k IM =

7.5V IB 200µA2

ONE SHOT SYNC 200ns OSC

1248 BD

CSET RSET