Boost, Flyback, SEPIC and Inverting Controller

The LT3757/LT3757A are wide input range, current mode, DC/DC controllers which are capable of generating either positive or negative output voltages. They can be configured as either a boost, flyback, SEPIC or inverting converter. The LT3757/LT3757A drive a low side external N-channel power MOSFET from an internal regulated 7.2V supply. The fixed frequency, current-mode architecture results in stable operation over a wide range of supply and output voltages.

The operating frequency of LT3757/LT3757A can be set with an external resistor over a 50kHz to 1MHz range, and can be synchronized to an external clock using the SYNC pin. A low minimum operating supply voltage of 2.9V, and a low shutdown quiescent current of less than 1µA, make the LT3757/LT3757A ideally suited for battery-operated systems.

The LT3757/LT3757A feature soft-start and frequency foldback functions to limit inductor current during startup and output short-circuit. The LT3757A has improved load transient performance compared to the LT3757.

Applications

* Automotive and Industrial Boost, Flyback, SEPIC and Inverting Converters

* Telecom Power Supplies

* Portable Electronic Equipment

* Wide Input Voltage Range: 2.9V to 40V

* Positive or Negative Output Voltage Programming with a Single Feedback Pin

* Current Mode Control Provides Excellent Transient Response

* Programmable Operating Frequency (50kHz to 1MHz) with One External Resistor

* Synchronizable to an External Clock