LT3804 Datasheet | Linear Technology

Final Electrical Specifications LT3804 Secondary Side Dual Output Controller with Opto Driver Features Regulates Two Secondary Outputs s Optocoupler Feedback Driver and Second Output Synchronous Driver Controller s True Differential Remote Sensing Regulation s High Switching Frequency: up to 800k Hz s Programmable Current Limit s Programmable Soft-Start and Power Good .. s Automatic Frequency Synchronization s Available in Thermally Enhanced 28-Lead TSSOP s DESCRIPTIO June 2003 The LT®3804 is a high efficiency step-down switching regulator with optocoupler feedback control for regulating multiple outputs in single-secondary winding isolated power supplies. The LT3804 contains an error amplifier and an optocoupler driver to regulate the first (main) output. For the second output regulation, the LT3804 contains a plete PWM controller to drive dual synchronous N-channel MOSFETs. With leading edge modulation, it operates with either current or voltage mode control of the primary side. The LT3804 is synchronized to the falling edge of the transformer secondary winding and can be used in singleended or double-ended isolated power converter topologies. A user selectable discontinuous conduction mode improves light load efficiency. True differential Kelvin sensing is used for each output feedback amplifier to achieve high regulation accuracy and design simplicity. Other Features include soft start, current limit and power good flags. U APPLICATIO S s s s s 48V Input Isolated DC/DC Converters Multiple Output Power Supplies Offline Converters DC/DC Power Modules , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO VIN 36V TO 72V VCC BIAS L1 1.8µH 0.003Ω LT3804 SYNC CL1N CL1P VCC CSET 390p F PGND TGATE SW BGATE Q2 x2 Q1 L2 1.8µH 0.003Ω - - Q4 OUT2 LTC1693-1 Q3 x2 OUT1 IN1 IN2 VOS1- TG BG GNDS1 604Ω CL2P CL2N VAOUT2 2.74k VFB1 VFB2 VAOUT1 OPTO GNDS2 3804 F01 - - VOS1+ LT3781 SG - VC + - VREF VFB -...