DESCRIPTION
The LT®1767 is a 1.25MHz monolithic buck switching regulator. A high efficiency 1.5A, 0.22Ω switch is included on the die together with all the control circuitry required to complete a high frequency, current mode switching regulator. Current mode control provides fast transient response and excellent loop stability.
New design techniques achieve high efficiency at high switching frequencies over a wide operating range. A low dropout internal regulator maintains consistent performance over a wide range of inputs from 24V systems to LiIon batteries. An operating supply current of 1mA improves efficiency, especially at lower output currents. Shutdown reduces quiescent current to 6µA. Maximum switch current remains constant at all duty cycles. Synchronization allows an external logic level signal to increase the internal oscillator from 1.4MHz to 2MHz.
The LT1767 is available in an 8-pin MSOP fused leadframe package and a low thermal resistance exposed pad package. Full cycle-by-cycle short-circuit protection and thermal shutdown are provided. High frequency operation allows the reduction of input and output filtering components and permits the use of chip inductors.

FEATURES
■ 1.5A Switch in a Small MSOP Package
■ Constant 1.25MHz Switching Frequency
■ High Power Exposed Pad (MS8E) Package
■ Wide Operating Voltage Range: 3V to 25V
■ High Efficiency 0.22Ω Switch
■ 1.2V Feedback Reference Voltage
■ Fixed Output Voltages of 1.8V, 2.5V, 3.3V, 5V
■ 2% Overall Output Tolerance
■ Uses Low Profile Surface Mount Components
■ Low Shutdown Current: 6µA
■ Synchronizable to 2MHz
■ Current Mode Loop Control
■ Constant Maximum Switch Current Rating at All Duty Cycles*

APPLICATIONS
■ DSL Modems
■ Portable Computers
■ Wall Adapters
■ Battery-Powered Systems
■ Distributed Power