LT3574 Isolated Flyback Converter Without an Opto-Coupler Fserutae Dnoitpircse n 3V to 40V Input Voltage Range The LT 3574 is a monolithic switching regulator specifi- n 0.65A, 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 0.65A, 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 LT3574 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 3W with NPN Driver no external power switch. The LT3574 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 16-Lead MSOP Package The output voltage is easily set with two external resistors a snoitacilpp and the transformer turns ratio. Off-the-shelf transformers are available for many applications. n Industrial, Automotive and Medical Isolated L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks Power Supplies and No R and ThinSOT are trademarks of Linear Technology Corporation. All other SENSE trademarks are the property of their respective owners. t lacipy a noitacilpp 5V Isolated Flyback Converter Load Regulation V IN B340A + 12V TO 24V V OUT 1.0 10F 3:1 5V 357k 0.22F 2k 0.35A V IN 22F 50H 5.6H SHDN/UVLO V = 24V IN 51.1k PMEG6010 0.5 V OUT 80.6k V = 12V IN R FB LT3574 0 R REF TC 6.04k R ILIM 0.5 SS SW VC GND TEST BIAS 28.7k 10k 59k 1.0 0 100 200 300 400 500 600 700 4.7F I (mA) 10nF 1nF OUT 3574 TA01b 3574 TA01 3574f OUTPUT VOLTAGE ERROR (%)LT3574 a etulosbMixa Mu M r sgnita p ni c no Fnoitarugi SW ............................................................................60V TOP VIEW V , SHDN/UVLO, R , BIAS .....................................40V IN FB GND 1 16 GND TEST 2 15 TC SS, VC, T , R , R ...............................................5V C REF ILIM GND 3 14 R REF SW 4 13 R FB Maximum Junction Temperature .......................... 125C V 5 12 VC IN BIAS 6 11 R Operating Junction Temperature Range ILIM SHDN/UVLO 7 10 SS GND 8 9 GND (Note 2) .................................................. 40C to 125C MS PACKAGE Storage Temperature Range ..................65C to 150C 16-LEAD PLASTIC MSOP T = 125C, = 120C/W, = 21C/W JMAX JA JC ro D re ni Fro Mnoita LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT3574EMS PBF LT3574EMS TRPBF 3574 16-Lead Plastic MSOP 40C to 125C LT3574IMS PBF LT3574IMS TRPBF 3574 16-Lead Plastic MSOP 40C to 125C Consult LTC Marketing for parts speciefi d with wider operating temperature ranges. *The temperature grade is identiefi d by a label on the shipping container. For more information on lead free part marking, go to: