Introduction to the LTC3569 Triple-Channel Buck Regulator

describe

The LTC®3569 contains three monolithic, synchronous step-down DC/DC converters. The device is designed for medium power applications and operates from an ^input voltage range of 2.5V to 5.5V. The operating frequency is adjustable from 1MHz to 3MHz, allowing the use of tiny, low-cost capacitors and inductors. The three output voltages can be independently set by level shifting the EN pin up to 15 times and lowering the 800mV FB reference by 25mV per cycle. The first step-down regulator provides up to 1200mA of load current. The other two step-down regulators provide 600mA each.

Alternatively, the two 600mA buck regulators can be configured to act as a controlled power stage and run in parallel with another internal buck regulator to provide higher load currents. When acting as parallel and slave output stages, discrete external components are shared and the available output currents are added together.

Features

● Three independent current-mode step-down DC/DC regulators (one 1.2A and two 600mA)

● Single pin can set VFB servo voltage from 800mV to as low as 425mV (25mV step)

● Pull VFB high to make each 600mA buck regulator a slave supply for higher current operation

● Pulse skipping or burst mode (BurST Mode?) operation

● Programmable switching frequency (1MHz to 3MHz) or fixed 2.25MHz

● Synchronizable (1.2MHz to 3MHz)

● VIN range: 2.5V to 5.5V

● All regulators are internally compensated

● PGOOD output flag

● Quiescent current <100μA (all regulators in Burst Mode operation)

Zero shutdown current

● With overheat and short circuit protection function

● Tiny 3mm x 3mm 20-pin QFN and thermally enhanced TSSOP FE-16 packages

Encapsulation

Typical Applications

application

● Portable applications with multiple power rails

● General purpose step-down DC/DC converter

● Dynamic voltage regulation application