Flyback Controller Improves Cross Regulation for Multiple
Output Applications – Design Note 344
Tom Hack
Also, outputs remain uncoupled when the rectifiers
are off, which contributes to poor cross regulation. Introduction
Flyback converters are often used in power supplies
requiring low to medium output power at several output
voltages. With a flyback, multiple outputs incur little additional cost or complexity—each additional output requires
only another transformer winding, rectifier and output
п¬Ѓlter capacitor. Power over Ethernet (PoE) applications
may require several low to medium power outputs
and are good candidates for multiple output flyback
converters. The LTC ®3806 is a new flyback controller that improves
load and cross regulation for multiple output flyback
converters. Multi-output systems that previously used
post regulators, multiple switching supplies or other
methods to provide tight output voltage tolerances can
now use lower cost flyback converters. The LTC3806
uses forced continuous conduction operation improving
cross regulation by keeping the rectifiers on and the
outputs coupled (via transformer action) for a larger
fraction of each power conversion cycle. The LTC3806
also uses synchronous rectiп¬Ѓcation to reduce rectiп¬Ѓer …