2/21/2005
1
Leadtrend Technology Corporation
LD7552-DS-00 February, 2005
Green-Mode PWM Controller
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.
Patent pending
Features
High-Voltage CMOS Process with Excellent ESD
Protection
Very Low Startup Current (Typical 5 A)
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
Applications
Switching AC/DC Adaptor and Battery Charger
Open Frame Switching Power Supply
384X Replacement
Note: Please see Application Information
Typical Application
OSC
16.0V/
11.4V
UVLO
Divider
40V
Control
Logic
EMI
Filter
RT
OUT
CS
VCC
GND
COMP
LD7552
photocoupler
AC
input
TL431
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