1

LT1509

Power Factor and

PWM Controller

+

–

–

+

–

+

–

+

–

+

+

–

–

+

+

–

200

11

16

13

+

–

–

+

4

15

19

18

1500 • BD01

7.5V

7.9V

16V TO 10V

14

µA

14

µA

7

µA

7V to

4.7V

EA

CA

CL

2.2V

M1

25k

1V

1.2V

14

10

7.5V

12

8

7

6

RAMP

50

µA

0.7V

RUN

RUN

R

RQ

S

OSC

55%

DELAY

200ns

BLANKING

5

GND1

3

17

GTDR1

16V

16V

1

GND2

2

GTDR2

20

9

OVP

SS1

SS2

PWM0K

+

–

+

–

+

–

R

S

Q

R

NOTE: PWM PULSE IS DELAYED BY 55% DUTY CYCLE AFTER PFC PULSE

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PFC and PWM Single Chip Solution

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Synchronized Operation up to 300kHz

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99% Power Factor over 20:1 Load Current Range

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Current Mode PWM

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Instantaneous Overvoltage Protection

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Dedicated Overvoltage Protection (OVP Pin)

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Minimal Line Current Dead Zone

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Typical 250

µA Start-Up Supply Current

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Line Switching Noise Filter

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Low Quiescent Current: 13mA

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Fast 2A Peak Current Gate Drivers

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Separate Soft Start Controls

The LT

switching power supplies utilizing active power factor

correction. The PFC section is identical to the LT1248 PFC

controller except the EN/SYNC pin is removed because

PFC and PWM are synchronized internally.

The current mode PWM section (the LT1508 is the volt-

age-mode counterpart) contains all the primary side func-

tions to convert the PFC preregulated high voltage output

to an isolated low voltage output. The PWM duty cycle is

internally limited to 47% (maximum 50%) to prevent

transformer saturation. PWM soft start begins when PFC

output reaches the preset voltage. In the event of brief line

loss, the PWM will be shut off when the PFC output voltage

drops below 73% of the preset value.

FEATURES

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

s

Universal Power Factor Corrected Power Supplies

and Preregulators