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L6565

January 2003

s

QUASI-RESONANT (QR) ZERO-VOLTAGE-

SWITCHING (ZVS) TOPOLOGY

s

LINE FEED FORWARD TO DELIVER

CONSTANT POWER vs. MAINS CHANGE

s

FREQUENCY FOLDBACK FOR OPTIMUM

STANDBY EFFICIENCY

s

PULSE-BY-PULSE & HICCUP-MODE OCP

s

ULTRA-LOW START-UP (< 70µA) AND

QUIESCENT CURRENT (< 3.5mA)

s

DISABLE FUNCTION (ON/OFF CONTROL)

s

REFERENCE VOLTAGE

s

±400mA TOTEM POLE GATE DRIVER WITH

UVLO PULL-DOWN

s

BLUE ANGEL, ENERGY STAR, ENERGY

2000 COMPLIANT

APPLICATIONS

s

TV/MONITOR SMPS

s

AC-DC ADAPTERS/CHARGERS

s

DIGITAL CONSUMER

s

PRINTERS, FAX MACHINES,

PHOTOCOPIERS AND SCANNERS

DESCRIPTION

The L6565 is a current-mode primary controller IC,

specifically designed to build offline Quasi-resonant

ZVS (Zero Voltage Switching at switch turn-on) fly-

back converters.

Quasi-resonant operation is achieved by means of a

transformer demagnetization sensing input that trig-

gers MOSFET's turn-on.

DIP8(Minidip)

SO-8

ORDERING NUMBERS:

L6565N

L6565D

QUASI-RESONANT SMPS CONTROLLER

BLOCK DIAGRAM

+

-

VOLTAGE

REGULATOR

INTERNAL

SUPPLY

+

-

2.5V

R1

R2

+

-

DRIVER

+

-

ZERO CURRENT

DETECTOR

2.1V

1.6V

8

1

23

4

ZCD

INV

COMP

VFF

CS

GD

7

5

GND

6

20V

40K

5pF

BLANKING

LINE VOLTAGE

FEEDFORWARD

Hiccup-mode

OCP

DISABLE

R

S

Q

STARTER

2 V

+

-

Hiccup-mode

OCP

Starter

STOP

Q

UVLO

Blanking

START