Features

• V_IN Range: 1.8V to 5.5V, 500mV After Start-Up
• Output Voltage Range: 2.2V to 15V
• 400mA Output Current for V_IN = 5V and V_OUT = 12V
• Output Disconnects from Input When Shut Down
• Synchronous Rectification: Up to 95% Efficiency
• Inrush Current Limit
• Up to 3MHz Adjustable Switching Frequency Synchronizable to External Clock
• Selectable Burst Mode® Operation: 25μA I_Q
• Output Overvoltage Protection
• Soft-Start
• <1μA I_Q in Shutdown
• 12-Lead, 3mm × 4mm Thermally Enhanced DFN Package

Typical Application

Description

The LTC®3121 is a synchronous step-up DC/DC converter with true output disconnect and inrush current limiting. The 1.5A current limit along with the ability to program output voltages up to 15V makes the LTC3121 well suited for a variety of demanding applications. Once started, operation will continue with inputs down to 500mV, extending run time in many applications.

The LTC3121 features output disconnect in shutdown, dramatically reducing input power drain and enabling V_OUT to completely discharge. Adjustable PWM switching from 100kHz to 3MHz optimizes applications for highest efficiency or smallest solution footprint. The oscillator can also be synchronized to an external clock for noise sensitive applications. Selectable Burst Mode operation reduces quiescent current to 25μA, ensuring high efficiency across the entire load range. An internal soft-start limits inrush current during start-up.

Other features include a <1μA shutdown current and robust protection under short-circuit, thermal overload, and output overvoltage conditions. The LTC3121 is offered in a low profile 12-lead (3mm × 4mm × 0.75mm) DFN package.