LTC1775

The LTC^®1775 is a synchronous step-down switchingregulator controller that drives external N-channel powerMOSFETs using few external components. Current modecontrol with MOSFET VDS sensing eliminates the need fora sense resistor and improves efficiency. Largely similarto the LTC1625, the LTC1775 has twice the maximumsense voltage for high current applications. The frequencyof a nominal 150kHz internal oscillator can be synchro-nized to an external clock over a 1.5:1 frequency range.Burst Mode^TMoperation at low load currents reducesswitching losses and low dropout operation extends oper-ating time in battery-powered systems. A forced continu-ous mode control pin can assist secondary windingregulation by disabling Burst Mode operation when themain output is lightly loaded.

Fault protection is provided by foldback current limitingand an output overvoltage comparator. An external ca-pacitor attached to the RUN/SS pin provides soft startcapability for supply sequencing. A wide supply rangeallows operation from 4V (4.3V for LTC1775I) to 36V at theinput and 1.19V to VIN at theoutput.