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Data sheet
    LD7575A   11/29/2007 1  Leadtrend Technology Corporation LD7575A-DS-00a November 2007 Green-Mode PWM Controller with High-Voltage Start-Up Circuit  Rev.00a General Description The LD7575A is a current-mode PWM controller with excellent power-saving operation. It features a high- voltage current source to directly supply the startup current from bulk capacitor and further to provide a lossless startup circuit. 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. Furthermore, the embedded over voltage protection, over load protection and the special green-mode control provide the solution for users to design a high performance power circuit easily. The LD7575A is offered in both SOP-8 and DIP-8 package. Features    High-Voltage (500V) Startup Circuit    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    OLP (Over Load Protection)    500mA Driving Capability Applications    Switching AC/DC Adapter and Battery Charger    Open Frame Switching Power Supply    LCD Monitor/TV Power Typical Application    LD7575A   2  Leadtrend Technology Corporation LD7575A-DS-00a November 2007 Pin Configuration   YY: Year code WW: Week code PP: Production codeSOP-8 & DIP-8 (TOP VIEW) 1 8 234765 TOP MARKYYWWPP      R   T   C   O   M   P   C   S   G   N   D   H   V   N   C   V   C   C   O   U   T   Ordering Information Part number Package Top Mark Shipping LD7575A PS SOP-8 PB Free LD7575APS 2500 /tape & reel LD7575A GS SOP-8 Green PackageLD7575AGS 2500 /tape & reel LD7575A PN DIP-8 PB Free LD7575APN 3600 /tube /Carton The LD7575A is ROHS Complaint/ Green Package. Pin Descriptions   PIN   NAME FUNCTION 1 RT This pin is to program the switching frequency. By connecting a resistor to ground to set the switching frequency. 2 COMP Voltage feedback pin (same as the COMP pin in UC384X), connecting a photo-coupler to close the control loop and achieve the regulation. 3 CS Current sense pin, connect to sense the MOSFET current 4 GND Ground 5 OUT Gate drive output to drive the external MOSFET 6 VCC Supply voltage pin 7 NC Unconnected Pin 8 HV Connect this pin to positive terminal of bulk capacitor to provide the startup current for the controller. When Vcc voltage trips the UVLO(on), this HV loop will be off to save the power loss on the startup circuit.    LD7575A   3  Leadtrend Technology Corporation LD7575A-DS-00a November 2007 Block Diagram OSC COMPCSOUT internal bias & Vref  VCCGND PWMComparator  RT 16.0V/10.0V Green-ModeControl Leading Edge Blanking2RR RSQ Vref OKPG ++ SlopeCompensation27.5V HV ∑ 0.85V30mS Delay5.0VOCPComparator OLPComparator OVPUVLOComparator    Driver Stage OVPComparator  RSQ VCC OKOLPPG8VPOR/2 Counter  clear  PORVbias32V1mA RSQ PG      LD7575A   4  Leadtrend Technology Corporation LD7575A-DS-00a November 2007 Absolute Maximum Ratings Supply Voltage VCC 30V High-Voltage Pin, HV -0.3V~500V COMP, RT, CS -0.3 ~7V Junction Temperature 150 ° C Operating Ambient Temperature -40 ° C to 85 ° C Storage Temperature Range -65 ° C to 150 ° C Package Thermal Resistance (SOP-8) 160 ° C/W Package Thermal Resistance (DIP-8) 100 ° C/W Power Dissipation (SOP-8, at Ambient Temperature = 85 ° C) 400mW Power Dissipation (DIP-8, at Ambient Temperature = 85 ° C) 650mW Lead temperature (Soldering, 10sec) 260 ° C ESD Voltage Protection, Human Body Model (except HV Pin) 3KV ESD Voltage Protection, Machine Model 200V   Gate Output Current 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. Recommended Operating Conditions Item Min. Max. Unit Supply Voltage Vcc 11 25 V Vcc Capacitor 10 47 μ F Switching Frequency 50 130 KHz

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