Features

• Wide Input Voltage Range: 3V to 40V
• Single Feedback Pin for Positive or Negative Output Voltage
• Internal 5A/40V Power Switch
• Current Mode Control Provides Excellent Transient Response
• Programmable Operating Frequency (100kHz to 1MHz) with One External Resistor
• Synchronizable to an External Clock
• Low Shutdown Current < 1μA
• Internal 5.2V Low Dropout Voltage Regulator
• Programmable Input Undervoltage Lockout with Hysteresis
• Programmable Soft-Start
• Thermally Enhanced QFN (5mm × 6mm) Package

Typical Application

Description

The LT®3957A is a wide input range, current mode DC/DC converter which is capable of generating either positive or negative output voltages. It can be configured as either a boost, flyback, SEPIC or inverting converter. It features an internal low side N-channel power MOSFET rated for 40V at 5A and driven from an internal regulated 5.2V supply. The fixed frequency, current-mode architecture results in stable operation over a wide range of supply and output voltages.

The operating frequency of LT3957A can be set with an external resistor over a 100kHz to 1MHz range, and can be synchronized to an external clock using the SYNC pin. A minimum operating supply voltage of 3V, and a low shutdown quiescent current of less than 1μA, make the LT3957A ideally suited for battery-powered systems.

The LT3957A features soft-start and frequency foldback functions to limit inductor current during start-up. The LT3957A has improved load transient performance compared to the LT3957.