LT8311
Synchronous Rectifier
Controller with Opto-Coupler
Driver for Forward Converters
DESCRIPTION FEATURES Wide Input Supply Range: 3.7V to 30V
n Preactive Mode: n No Pulse Transformer Required n DCM Operation at Light Load
n SYNC Mode: n FCM or DCM Operation at Light Load n Achieves Highest Efficiency
n 1.5% Feedback Voltage Reference
n 10mA Opto-Coupler Driver
n Output Power Good Indicator
n Integrated Soft-Start Function The LT®8311 is used on the secondary side of a forward
converter to provide synchronous MOSFET control and
output voltage feedback through an opto-coupler. The
LT8311’s unique preactive mode allows control of the
secondary-side MOSFETs without requiring a traditional
pulse transformer for primary-to secondary-side communication. In preactive mode, the output inductor current
operates in discontinuous conduction mode (DCM) at
light load. If forced continuous mode (FCM) operation is
desired at light load, the LT8311 can, alternatively, be used
in SYNC mode, where a pulse transformer is required to
send synchronous control signals from the primary-side
IC to the LT8311. n APPLICATIONS Offline and HV Car Battery Isolated Power Supplies 48V Isolated Power Supplies
n Industrial, Automotive and Military Systems The LT8311 offers a full featured opto-coupler controller, …