LT1725 Datasheet | Linear Technology

.. LT1725 General Purpose Isolated Flyback Controller Features s s DESCRIPTIO s s s s s s s Drives External Power MOSFET with External ISENSE Resistor Application Input Voltage Limited Only by External Power ponents Senses Output Voltage Directly from Primary Side Winding- No Optoisolator Required Accurate Regulation Without User Trims Regulation Maintained Well into Discontinuous Mode Switching Frequency from 50k Hz to 250k Hz with External Capacitor Optional Load pensation Optional Undervoltage Lockout Available in 16-Pin SO and SSOP Packages The LT®1725 is a monolithic switching regulator controller specifically designed for the isolated flyback topology. It drives the gate of an external MOSFET and is generally powered from a third transformer winding. These Features allow for an application input voltage limited only by external power path ponents. The third transformer winding also provides output voltage feedback information, such that an optoisolator is not required. Its gate drive capability coupled with a suitable external MOSFET can deliver load power up to tens of watts. The LT1725 has a number of Features not found on most other switching regulator ICs. By utilizing current mode switching techniques, it provides excellent AC and DC line regulation. Its unique control circuitry can maintain regulation well into discontinuous mode in most applications. Optional load pensation circuitry allows for improved load regulation. An optional undervoltage lockout pin halts operation when the application input voltage is too low. An optional external capacitor implements a softstart function. A 3V output is available at up to several m A for powering primary side application circuitry. U APPLICATIO S s s s Tele Isolated Converters Offline Isolated Power Supplies Instrumentation Power Supplies , LTC and LT are registered trademarks of Linear Technology Corporation. TYPICAL APPLICATIO 48V to Isolated 5V Converter CTX02-14989...