No R, Low Input Voltage, Synchronous DC/DC Controller with Output Tracking

The LTC3809-1 is a synchronous step-down switching regulator controller that drives external complementary power MOSFETs using few external components. The constant frequency current mode architecture with MOSFET VDS sensing eliminates the need for a current sense resistor and improves efficiency.

Optional Burst Mode operation provides high efficiency operation at light loads. 100% duty cycle provides low dropout operation, extending operating time in battery-powered systems. Burst Mode is inhibited when the MODE pin is pulled low to reduce noise and RF interference.

The LTC3809-1 allows either coincident or ratiometric output voltage tracking. Switching frequency is fixed at 550kHz. Fault protection is provided by an overvoltage comparator and a short-circuit current limit comparator.

The LTC3809-1 is available in tiny footprint thermally enhanced DFN and 10-lead MSOP packages.

Features

Package

LTC3809

PLL, Selectable Spread Spectrum, Power Good

3x3 DFN-10, MS-10E

LTC3809-1

Tracking

3x3 DFN-10, MS-10E

LTC3808

PLL, Selectable Spread Spectrum, Tracking, Power Good

4x3 DFN-14, SSOP-16

Applications

* 1- or 2-Cell Lithium-Ion Powered Devices

* Notebook and Palmtop Computers, PDAs

* Portable Instruments

* Distributed DC Power Systems

* Programmable Output Voltage Tracking

* No Current Sense Resistor Required

* Constant Frequency Current Mode Operation for Excellent Line and Load Transient Response

* Wide VIN Range: 2.75V to 9.8V

* Wide VOUT Range: 0.6V to VIN

* 0.6V ±1.5% Reference

* Low Dropout Operation: 100% Duty Cycle * Selectable Burst Mode®/Pulse-Skipping/Forced Continuous Operation