LT3573 Isolated Flyback Converter without an Opto-Coupler FEATURESDESCRIPTION n 3V to 40V Input Voltage Range The LT®3573 is a monolithic switching regulator specifi- n 1.25A, 60V Integrated NPN Power Switch cally designed for the isolated flyback topology. No third n Boundary Mode Operation winding or opto-isolator is required for regulation. The n No Transformer Third Winding or part senses the isolated output voltage directly from the Opto-Isolator Required for Regulation primary-side flyback waveform. A 1.25A, 60V NPN power n Improved Primary-Side Winding Feedback switch is integrated along with all control logic into a Load Regulation 16-lead MSOP package. n VOUT Set with Two External Resistors The LT3573 operates with input supply voltages from n BIAS Pin for Internal Bias Supply and Power 3V to 40V, and can deliver output power up to 7W with NPN Driver no external power devices.The LT3573 utilizes boundary n Programmable Soft-Start mode operation to provide a small magnetic solution with n Programmable Power Switch Current Limit improved load regulation. n Thermally Enhanced 16-Lead MSOP L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks and No R APPLICATIONS SENSE and ThinSOT are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents, including 5438499 and 7471522. n Industrial, Automotive and Medical Isolated Power Supplies TYPICAL APPLICATION5V Isolated Flyback Converter VIN 12V TO 24V Load Regulation B340A 3:1 3 10µF V + OUT 357k 2k V 0.22µF 5V, 0.7A IN 2 SHDN/UVLO 24µH 2.6µH 47µF 51.1k PMEG6010 V – 1 OUT 80.6k RFB LT3573 TAGE ERROR (%) 0 VIN = 24V RREF V TC IN = 12V 6.04k –1 RILIM SS SW OUTPUT VOL –2 VC GND TEST BIAS –3 28.7k 10k 20k 0 200 400 600 800 1000 1200 1400 IOUT (mA) 10nF 1nF 4.7µF 3573 TA01b 3573 TA01 3573fd For more information www.linear.com/LT3573 1 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
