Features

• High Efficiency: Up to 95%
• Constant Frequency 350kHz Operation
• 2.65V to 8.5V V_IN Range
• V_OUT from 0.8V to V_IN, I_OUT to 500mA
• No Schottky Diode Required
• Synchronizable Up to 525kHz
• Selectable Burst Mode™ Operation
• Low Dropout Operation: 100% Duty Cycle
• Precision 2.5V Undervoltage Lockout
• Secondary Winding Regulation
• Current Mode Operation for Excellent Line and Load Transient Response
• Low Quiescent Current: 200µA
• Shutdown Mode Draws Only 15µA Supply Current
• ±1.5% Reference Accuracy
• Available in 8-Lead SO Package

Typical Application

Description

The LTC1627 is a monolithic current mode synchronous buck regulator using a fixed frequency architecture. The operating supply range is from 8.5V down to 2.65V, making it suitable for one or two lithium-ion battery-powered applications. Burst Mode operation provides high efficiency at low load currents. 100% duty cycle provides low dropout operation, which extends operating time in battery-operated systems.

The operating frequency is internally set at 350kHz, allowing the use of small surface mount inductors. For switching noise sensitive applications it can be externally synchronized up to 525kHz. The SYNC/FCB control pin guarantees regulation of secondary windings regardless of load on the main output by forcing continuous operation. Burst Mode operation is inhibited during synchronization or when the SYNC/FCB pin is pulled low to reduce noise and RF interference. Soft-start is provided by an external capacitor.

Optional bootstrapping enhances the internal switch drive for single lithium-ion cell applications. The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode, saving components and board space. The LTC1627 comes in an 8-lead SO package.