The LT1105CN8#PBF is an offline Switching Regulator designed for high input voltage applications using an external FET switch whose source is driven by the open collector output of the LT1103. For higher power applications or additional switch current flexibility, the LT1105 is available and its totem pole output drives the gate of an external FET. Unique design of this eliminates the need for an optocoupler while still providing ±1% load and line regulation in a magnetic flux-sensed converter. This significantly simplifies the design of offline power supplies and reduces the number of components which must cross the isolation barrier to one, the transformer. The current mode switching techniques are well suited to transformer isolated fly-back and forward topologies while providing ease of frequency compensation with a minimum of external components. Low external part count for a typical application combines with a 200kHz maximum switching frequency to achieve high power density.
● Fully protected against overloads
● Overvoltage lockout of main supply
● Protected against under drive or overdrive to FET
● Operates in continuous or discontinuous mode
● Ideal for fly-back and forward topologies
● Isolated fly-back mode has fully floating outputs
● Internal 1A totem-pole driver
● Start-up mode draws only 200µA
● ±1% Line and load regulation with no optocoupler
