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

The LTC3873 is a constant frequency, current mode, boost, flyback or SEPIC DC/DC controller that drives an N-channel power MOSFET in high input and output voltage converter applications. Soft-start can be programmed using an external capacitor.

The LTC3873 provides ±1.5% output voltage accuracy and consumes only 300μA quiescent current during normal operation and only 55μA during micropower start-up. Using a 9.3V internal shunt regulator, the LTC3873 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.

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

LTC3873

LTC3873-5

VCC UV+

8.4V

4.1V

VCC UV–

4V

2.9V

Applications

* Telecom Power Supplies

* 42V and 12V Automotive Power Supplies

* Portable Electronic Equipment

* 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

* Maximum 60V on SW Node with RDS(ON) Sensing