LTC1159-5 Datasheet

• Operation from 4V to 40V Input Voltage
• 20µA Supply Current in Shutdown
• High Efficiency Maintained Over Wide Current Range
• Current Mode Operation for Excellent Line and Load Transient Response
• Very Low Dropout Operation: 100% Duty Cycle
• Short-Circuit Protection
• Synchronous FET Switching for High Efficiency
• Adaptive Non-Overlap Gate Drives
• Ultrahigh Efficiency: Up to 95%
• Available in SSOP and SO Packages

• Step-Down and Inverting Regulators
• Notebook and Palmtop Computers
• Portable Instruments
• Battery-Operated Digital Devices
• Industrial Power Distribution
• Avionics Systems
• Telecom Power Supplies

The LTC1159-5 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 LTC1159-5 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.