No R Constant Frequency Current Mode Boost/Flyback/SEPIC DC/DC Controller

The LTC3873-5 is a constant frequency current mode controller for boost, flyback or SEPIC DC/DC converters designed to drive an N-channel MOSFET for high input and output voltage converter applications.

The LTC3873-5 provides ±1.5% output voltage accuracy and consumes only 300μA quiescent current during normal operation and only 50μA during micropower start-up. Using a 9.3V internal shunt regulator, the LTC3873-5 can be powered from a high input voltage through a resistor or it can be powered directly from a low impedance DC voltage of 9V or less. Soft-start can be programmed using an external capacitor.

The LTC3873-5 is available in 8-lead ThinSOT and 2mm × 3mm DFN packages.

LTC3873

LTC3873-5

VCC UV+

8.4V

3.9V

VCC UV–

4V

2.9V

Applications

* Telecom Power Supplies

* Automotive Power Supplies

* PoE Applications

* VIN and VOUT Limited Only by External Components

* Internal or Programmable External Soft-Start

* Constant Frequency 200kHz Operation

* Adjustable Current Limit

* Current Sense Resistor Optional