The LTC1159 series is a family of synchronous step-down switching regulator controllers featuring automatic Burst Mode™operation to maintain high efficiencies at low output currents. These devices drive external complementary power MOSFETs at switching frequencies up to 250kHz using a constant off-time current-mode architecture.A separate pin and on-board switch allow the MOSFET driver power to be derived from the regulated output voltage providing significant efficiency improvement when operating at high input voltages. The constant off-time current-mode architecture maintains constant ripple current in the inductor and provides excellent line and load transient response. The output current level is user programmable via an external current sense resistor.The LTC1159 automatically switches to power saving Burst Mode operation when load current drops below approximately 15% of maximum current. Standby current is only 300µA while still regulating the output and shutdown current is a low 20µA.ApplicationsStep-Down and Inverting RegulatorsNotebook and Palmtop ComputersPortable InstrumentsBattery-Operated Digital DevicesIndustrial Power DistributionAvionics SystemsTelecom Power Supplies