Features

• OBSOLETE:  For Information Purposes Only.  Contact Linear Technology for Potential Replacement.
• Dual Outputs: 3.3V and 5V, Adjustable and 5V
• Wide VIN Range: 4V to 40V
• Ultra-High Efficiency: Up to 95%
• Low Supply Current in Shutdown: 20µA
• Current Mode Operation for Excellent Line and Load Transient Response
• High Efficiency Maintained Over a Wide Output Current Range
• Independent Micropower Shutdown
• Very Low Dropout Operation: 100% Duty Cycle
• Synchronous FET Switching for High Efficiency
• Available in Standard 28-Pin SSOP

Typical Application

Description

The LTC1267 series are dual synchronous step-down switching regulator controllers featuring automatic Burst Mode (TM) operation to maintain high efficiencies at low output currents. The LTC1267 is composed of two separate regulator blocks, each driving a pair of external complementary power MOSFETs at switching frequencies up to 400kHz. The LTC1267 uses a constant off-time current mode architecture to provide constant ripple current in the inductor and provide excellent line and load transient response.

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 voltage. The output current level is user-programmable via an external current sense resistor.

The LTC1267 series is ideal for applications requiring dual output voltages with high conversion efficiencies over a wide load current range in a small amount of board space.