LD7552BPS

LD7552B

1/2/2008

Green-Mode PWM Controller with Integrated Protections

Rev. 01a

General Description

The LD7552B are low cost, low startup current, current

mode PWM controllers with green-mode power- saving

operation.

The

integrated

functions

include

the

leading-edge blanking of the current sensing, internal slope

compensation. They provide the users a superior AC/DC

power application of higher efficiency, low external

component counts, and lower cost solution.

Furthermore, LD7552B feature more protections like OLP

(Over Load Protection) and OVP (Over Voltage Protection)

to eliminate the external protection circuits. It is designed for

the switching adaptor with 30W~60W output, offered in both

SOP-8 and DIP-8 package.

Features

High-Voltage CMOS Process with Excellent ESD

protection

Very Low Startup Current (<20μA)

Current Mode Control

Non-audible-noise Green Mode Control

UVLO (Under Voltage Lockout)

LEB (Leading-Edge Blanking) on CS Pin

Programmable Switching Frequency

Internal Slope Compensation

OVP (Over Voltage Protection) on Vcc Pin

OLP (Over Load Protection)

500mA Driving Capability

Applications

Switching AC/DC Adaptor and Battery Charger

Open Frame Switching Power Supply

384X Replacement

Typical Application

AC

input

EMI

Filter

VCC

32V

16.0V

/10.0V

UVLO

OUT

RT

COMP

LD7552B

OSC

Control

Logic

photocoupler

Divider

CS

GND

TL431

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Leadtrend Technology Corporation

LD7552B-DS-01a January 2008

LD7552B

Pin Configuration

SOP-8 & DIP-8 (TOP VIEW)

VCC

OUT

8

7

6

NC

5

CS

TOP MARK

YYWWPP

1

2

3

4

YY: Year code (D: 2004, E: 2005…..)

WW: week code

PP: production code

GND

VCC

Ordering Information

Part number

LD7552B PS

LD7552B GS

LD7552B PN

SOP-8

SOP-8

DIP-8

Package

PB Free

Green Package

PB Free

TOP MARK

LD7552BPS

LD7552BGS

LD7552BPN

Shipping

2500 /tape & reel

2500 /tape & reel

3600 /tube /carton

The LD7552B is ROHS Compliant/ Green Package.

Pin Descriptions

PIN

1

2

3

4

5

6

7

8

NAME

GND

COMP

photo-coupler to close the control loop and achieve the regulation.

VCC

RT

to set the switching frequency.

NC

CS

VCC

OUT

Unconnected pin

Current sense pin, connect to sense the MOSFET current

Supply voltage pin

Gate drive output to drive the external MOSFET

Supply voltage pin

This pin is to program the switching frequency. By connecting a resistor to ground

Ground

Voltage feedback pin (same as the COMP pin in UC384X), By connecting a

FUNCTION

COMP

RT

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Leadtrend Technology Corporation

LD7552B-DS-01a January 2008

LD7552B

Block Diagram

∑

*

Note: OLP delay is 60mS when the switching frequency is set as 65KHz.

The OLP delay time is proportional to the period of switching cycle.

That is,

T

OLP

_

delay

∝

T

s

=

1

.

f

s

3

Leadtrend Technology Corporation

LD7552B-DS-01a January 2008

LD7552B

Absolute Maximum Ratings

Supply Voltage VCC

COMP, RT, CS

Junction Temperature

Operating Ambient Temperature

Storage Temperature Range

Package Thermal Resistance (SOP-8)

Package Thermal Resistance (DIP-8)

Power Dissipation (SOP-8, at Ambient Temperature = 85°C)

Power Dissipation (DIP-8, at Ambient Temperature = 85°C)

Lead temperature (Soldering, 10sec)

ESD Voltage Protection, Human Body Model

ESD Voltage Protection, Machine Model

Gate Output Current

30V

-0.3 ~7V

150°C

-40°C to 85°C

-65°C to 150°C

160°C/W

100°C/W

400mW

650mW

260°C

3KV

300V

500mA

Caution:

Stresses beyond the ratings specified in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only

rating and operation of the device at these or any other conditions above those indicated in the operational sections of this specification is not

implied.

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Leadtrend Technology Corporation

LD7552B-DS-01a January 2008

LD7552B

Electrical Characteristics

(T

A

= +25 C unless otherwise stated, V

CC

=15.0V)

PARAMETER

Supply Voltage (Vcc Pin)

Startup Current

Operating Current

(with 1nF load on OUT pin)

UVLO (Off)

UVLO (On)

OVP Level

Voltage Feedback (Comp Pin)

Short Circuit Current

Open Loop Voltage

Green Mode Threshold VCOMP

Current Sensing (CS Pin)

Maximum Input Voltage, Vcs(off)

Leading Edge Blanking Time

Input impedance

Delay to Output

Oscillator (RT pin)

Frequency

Green Mode Frequency

Temp. Stability

Voltage Stability

Gate Drive Output (OUT Pin)

Output Low Level

Output High Level

Rising Time

Falling Time

OLP (Over Load Protection)

OLP Trip Level

OLP Delay Time (note)

V

COMP

(OLP)

Fs=65KHz

5.0

60

V

mS

VCC=15V, Io=20mA

VCC=15V, Io=20mA

Load Capacitance=1000pF

Load Capacitance=1000pF

9

50

30

160

60

1

V

V

nS

nS

RT=100KΩ

Fs=65KHz

(-40°C ~105°C)

(VCC=11V-25V)

60

65

20

5

1

70

KHz

KHz

%

%

1

100

0.80

0.85

350

0.90

V

nS

MΩ

nS

V

COMP

=0V

COMP pin open

1.5

6.0

2.35

2.2

mA

V

V

V

COMP

=0V

V

COMP

=3V

Protection tripped (OLP, OVP)

9.0

15.0

26.5

8

2.0

2.5

0.5

10.0

16.0

28.0

11.0

17.0

29.5

20

3.0

μA

mA

mA

mA

V

V

V

CONDITIONS

MIN

TYP

MAX

UNITS

o

Note: The OLP delay time is proportional to the period of switching cycle.

frequency and the shorter OLP delay time.

So that, the lower RT value will set the higher switching

5

Leadtrend Technology Corporation

LD7552B-DS-01a January 2008