1

LT1248

Power Factor Controller

–

+

–

+

–

+

200

16V TO 10V

2.6V/

2.2V

7.5V

7.9V

12

µA

5V

EA

–

+

–

+

–

+

–

+

2.2V

32k

7

µA

7.5V

–

+

0.7V

ONE SHOT

200ns

OSC

R

R

S

Q

13

6

11

8

10

7

9

5

4

32

1

15

16

12

14

SS

OVP

EN/SYNC

RUN

CA

RUN

1 6V

GND

–

+

GTDR

1248 BD

SYNC

M1

The LT

universal off-line power systems. By using fixed high

frequency PWM current averaging, without the need for

slope compensation, the LT1248 achieves far lower line

current distortion with a smaller magnetic element than

systems that use either peak-current detection or zero

current switching approaches in both continuous and

discontinuous modes of operation.

The LT1248 uses a multiplier containing a square gain

function from the voltage amplifier to reduce the AC gain

at light output load and thus maintains low line current

distortion and high system stability. The LT1248 also

provides filtering capability to reject line switching noise

which can cause instability when fed into the multiplier.

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 300kHz.

s

High Power Factor Over Wide Load Range

with Line Current Averaging

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International Operation Without Switches

s

Instantaneous Overvoltage Protection

s

Minimal Line Current Dead Zone

s

Typical 250

µA Start-Up Supply Current

s

Rejects Line Switching Noise

s

Synchronization Capability

s

Low Quiescent Current: 9mA

s

Fast 1.5A Peak Current Gate Driver

s

Universal Power Factor Corrected Power Supplies

s

Preregulators Up To 1500W

, LTC and LT are registered trademarks of Linear Technology Corporation.

FEATURES

DESCRIPTIO

APPLICATIO S

BLOCK DIAGRA