LTC1698

U U LTC1698 Isolated Secondary Synchronous Rectifier Controller FEATURES s High Efficiency Over Wide Load Current Range s ±0.8% Output Voltage Accuracy s Dual N-Channel MOSFET Synchronous Drivers s Pulse Transformer Synchronization s Optocoupler Feedback Driver s Programmable Current Limit Protection s ±5% Margin Output Voltage Adjustment s Adjustable Overvoltage Fault Protection s Power Good Flag s Auxiliary 3.3V Logic Supply s Available in 16-Lead SSOP and SO Packages U APPLICATIO S s 48V Input Isolated DC/DC Converters s Isolated Telecommunication Power Systems s Distributed Power Step-Down Converters s Industrial Control Systems s Automotive and Heavy Equipment DESCRIPTIO The LTC®1698 is a precision secondary-side forward converter controller that synchronously drives external N-channel MOSFETs. It is designed for use with the LT®3781 primary-side synchronous forward converter controller to create a completely isolated power supply. The LT3781 synchronizes the LTC1698 through a small pulse transformer and the LTC1698 drives a feedback optocoupler to close the feedback loop. Output accuracy of ±0.8% and high efficiency over a wide range of load currents are obtained. The LTC1698 provides accurate secondary-side current limit using an external current sense resistor. The input voltage at the MARGIN pin provides ±5% output voltage adjustment. A power good flag and overvoltage input are provided to ensure proper power supply conditions. An auxiliary 3.3V logic supply is in...