Features

• 3A Switch in a Thermally Enhanced 16-Lead TSSOP or 8-Lead SO Package
• Constant 1.25MHz Switching Frequency
• Wide Operating Voltage Range: 3V to 25V
• High Efficiency 0.09Ω Switch
• 1.2V Feedback Reference Voltage
• Uses Low Profile Surface Mount Components
• Low Shutdown Current: 15µA
• Synchronizable to 2MHz
• Current Mode Loop Control
• Constant Maximum Switch Current Rating at All Duty Cycles*
• Available in 8-Lead SO and 16-Lead Thermally Enhanced TSSOP Packages

Typical Application

Description

The LT1765 is a 1.25MHz monolithic buck switching regulator. A high efficiency 3A, 0.09Ω switch is included on the die together with all the control circuitry required to construct 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 voltage range. A low dropout internal regulator maintains consistent performance over a wide range of inputs from 24V systems to Li-Ion batteries. An operating supply current of 1mA improves efficiency, especially at lower output currents. Shutdown reduces quiescent current to 15µA. Maximum switch current remains constant at all duty cycles. Synchronization allows an external logic level signal to increase the internal oscillator into the range of 1.6MHz to 2MHz.

Full cycle-by-cycle current control and thermal shutdown are provided. High frequency operation allows the reduction of input and output filtering components and permits the use of chip inductors.