LD7552IS Leadtrend Technology, LD7552IS Datasheet

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LD7552IS

Manufacturer Part Number
LD7552IS
Description
Manufacturer
Leadtrend Technology
Datasheet

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Part Number:
LD7552IS
Quantity:
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General Description
The LD7552 is a low cost, low startup current, current mode
PWM controller with green-mode power-saving operation.
The integrated functions such as the leading-edge blanking
of the current sensing, internal slope compensation and the
small package provide the users a high efficiency, minimum
external component counts, and low cost solution for AC/DC
power applications.
The special green-mode control does not only achieve low
power consumption but also offer a non-audible-noise
operation when the LD7552 operates under light load or no
load condition.
The LD7552 is designed for the switching adaptor with
30W~60W output. The LD7552 is offered in both SOP-8 and
DIP-8 package.
Typical Application
Leadtrend Technology Corporation
LD7552-DS-00 February, 2005
Patent pending
AC
input
Filter
EMI
COMP
RT
Green-Mode PWM Controller
40V
Divider
OSC
16.0V/
11.4V
LD7552
VCC
GND
UVLO
Control
Logic
1
Features
Applications
OUT
CS
High-Voltage CMOS Process with Excellent ESD
Protection
Very Low Startup Current (Typical 5µA)
Under Voltage Lockout (UVLO)
Current Mode Control with Cycle-by-Cycle Peak
Current Limiting
Leading-Edge Blanking on CS Pin
Programmable Switching Frequency
Internal Slope Compensation
Proprietary Green-Mode Control for Power Saving
Non-audible-noise Green Mode Control
500mA Driving Capability
Switching AC/DC Adaptor and Battery Charger
Open Frame Switching Power Supply
384X Replacement
1
Note: Please see Application Information
photocoupler
TL431
LD7552
2/21/2005
1

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LD7552IS Summary of contents

Page 1

... Patent pending Typical Application EMI AC input Filter RT COMP Leadtrend Technology Corporation LD7552-DS-00 February, 2005 Green-Mode PWM Controller Features High-Voltage CMOS Process with Excellent ESD Protection Very Low Startup Current (Typical 5µA) Under Voltage Lockout (UVLO) Current Mode Control with Cycle-by-Cycle Peak ...

Page 2

... YY: Year code (D: 2004, E: 2005…..) WW: week code TOP MARK PP: production code YYWWPP Package TOP MARK SOP-8 LD7552IS SOP-8 (PB Free) LD7552BS DIP-8 LD7552IN DIP-8 (PB Free) LD7552BN FUNCTION 2 LD7552 Shipping 2500 /tape & reel 2500 /tape & reel 3600 /tube /carton ...

Page 3

... Storage Temperature Range Package thermal resistance (DIP-8) Package thermal resistance (SOP-8) Lead temperature (LD7552IS & LD7552IN, Soldering, 10sec) Lead temperature (LD7552BS & LD7552BN, Soldering, 10sec) 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 ...

Page 4

... 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 Leadtrend Technology Corporation LD7552-DS-00 February, 2005 =15.0V) CC CONDITIONS V =0V COMP V =3V COMP V =open ...

Page 5

... Temperature (°C) Fig. 1 UVLO (Off) vs. Temperature 72.0 71.0 70.0 69.0 68.0 67.0 66.0 -40 - Temperature (°C) Fig. 3 Frequency vs. Temperature 75.9 75.6 75.3 75.0 74.7 74.4 -40 - Temperature (°C) Fig. 5 Duty-Cycle (max.) vs. Temperature Leadtrend Technology Corporation LD7552-DS-00 February, 2005 17.0 16.8 16.4 16.0 15.6 15.2 14.8 14.4 14 100 120 18.2 18.0 17.8 17.6 17.4 17.2 17 100 120 60 80 100 120 5 LD7552 -40 -20 ...

Page 6

... The lower startup current requirement on the PWM controller will help to increase the R1 value and then reduce the power consumption on R1. By using CMOS process and the Leadtrend Technology Corporation LD7552-DS-00 February, 2005 special circuit design, the maximum startup current of LD7552 is only 25µA. ...

Page 7

... An output stage of a CMOS buffer, with typical 500mA driving capability, is incorporated to drive a power MOSFET directly. And the maximum duty-cycle of LD7552 is limited to 75% to avoid the transformer saturation. Leadtrend Technology Corporation LD7552-DS-00 February, 2005 Oscillator and Switching Frequency Connecting a resistor from RT pin to GND according to the ...

Page 8

... What LD7552 used to implement the power-saving operation is Leadtrend Technology’s own IP approach, as shown in the block diagram, 2 oscillators are implemented in LD7552. The first oscillator is to take care the normal switching frequency, which can be set by the RT pin through an external resistor ...

Page 9

... Package Information SOP-8 Symbols θ Leadtrend Technology Corporation LD7552-DS-00 February, 2005 Dimensions in Millimeters MIN MAX 4.801 5.004 3.810 3.988 1.346 1.753 0.330 0.508 1.194 1.346 0.178 0.229 0.102 0.254 5.791 6.198 0.406 1.270 0° ...

Page 10

... Important Notice Leadtrend Technology Corp. reserves the right to make changes or corrections to its products at any time without notice. Customers should verify the datasheets are current and complete before placing order. Leadtrend Technology Corporation LD7552-DS-00 February, 2005 ...

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