LT1681

The LT^®1681 controller simplifies the design of high powersynchronous dual transistor forward DC/DC converters. Thepart employs fixed frequency current mode control andsupports both isolated and nonisolated topologies. The ICdrives external N-channel power MOSFETs and operates withnput voltages up to 72V.

The LT1681's operating frequency is programmable and canbe synchronized up to 350kHz. Switch phase is also con-rolled during synchronized operation to accommodate mul-iple converter systems. Internal logic guarantees 50% maxi-mum duty cycle operation to prevent transformer saturation.

The LT1681 incorporates a soft-start feature that provides acontrolled increase in supplied current during start-up andafter an undervoltage lockout or overvoltage/overcurrentevent.

The part is available in a 20-lead wide SO package to supporthigh voltage pin-to-pin clearance.