LT3573 Isolated Flyback Converter without an Opto-Coupler FEATURES DESCRIPTION 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 V Set with Two External Resistors OUT 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 and ThinSOT are trademarks of Linear Technology Corporation. All other SENSE trademarks are the property of their respective owners. Protected by U.S. Patents, including APPLICATIONS 5438499 and 7471522. n Industrial, Automotive and Medical Isolated Power Supplies TYPICAL APPLICATION 5V Isolated Flyback Converter V IN Load Regulation 12V TO 24V B340A 3 3:1 + 10F V OUT 2k 357k 0.22F 5V, 0.7A V IN 2 24H 2.6H SHDN/UVLO 47F 51.1k PMEG6010 1 V OUT 80.6k R FB 0 V = 24V LT3573 IN R REF V = 12V IN TC 6.04k 1 R ILIM SS SW 2 VC GND TEST BIAS 3 28.7k 10k 20k 0 200 400 600 800 1000 1200 1400 I (mA) OUT 4.7F 10nF 1nF 3573 TA01b 3573 TA01 3573fd 1 For more information www.linear.com/LT3573 OUTPUT VOLTAGE ERROR (%)LT3573 ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION (Note 1) TOP VIEW SW ............................................................................60V GND 1 16 GND V , SHDN/UVLO, R , BIAS .....................................40V IN FB 2 TEST 15 TC GND 3 14 R REF SS, V , T , R , R ...............................................5V C C REF ILIM 4 SW 13 R FB 17 V 5 12 V Maximum Junction Temperature .......................... 125C IN C 6 BIAS 11 R ILIM SHDN/UVLO 7 10 SS Operating Junction Temperature Range (Note 2) 8 GND 9 GND LT3573E ............................................ 40C to 125C MSE PACKAGE 16-LEAD PLASTIC MSOP Storage Temperature Range ..................65C to 150C = 50C/W, = 10C/W JA JC EXPOSED PAD (PIN 17) IS GND, MUST BE CONNECTED TO GND ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3573EMSE PBF LT3573EMSE TRPBF 3573 16-Lead Plastic MSOP 40C to 125C LT3573IMSE PBF LT3573IMSE TRPBF 3573 16-Lead Plastic MSOP 40C to 125C Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container. For more information on lead free part marking, go to: