Features

• Three Independent Current Mode Buck DC/DC Regulators (1.2A and 2 × 600mA)
• Single Pin Programmable V_FB Servo Voltages from 800mV Down to 425mV (in 25mV Steps)
• Pull V_FB High to Make Each 600mA Buck a Slave for Higher Current Operation
• Pulse-Skipping or Burst Mode® Operation
• Programmable Switching Frequency (1MHz to 3MHz) or Fixed 2.25MHz
• Synchronizable (1.2MHz to 3MHz)
• V_IN Range 2.5V to 5.5V
• All Regulators Internally Compensated
• PGOOD Output Flag
• Quiescent Current <100μA (All Regulators in Burst Mode Operation)
• Zero Shutdown Current
• Overtemperature and Short-Circuit Protection
• Tiny 3mm × 3mm, 3mm × 4mm 20-Lead QFN and Thermally Enhanced TSSOP FE-16 Packages

Typical Application

Description

The LTC®3569 contains three monolithic, synchronous step-down DC/DC converters. Intended for medium power applications, it operates over a 2.5V to 5.5V input voltage range. The operating frequency is adjustable from 1MHz to 3MHz, allowing the use of tiny, low cost capacitors and inductors. The three output voltages are independently programmable by toggling the EN pins up to 15 times, lowering the 800mV FB references by 25mV per cycle. The first buck regulator sources load currents up to 1200mA. The other two buck regulators each provide 600mA.

The two 600mA buck regulators can also be configured to operate as slave power stages, running in parallel with another internal buck regulator to supply higher load currents. When operating as parallel, slave output stages, discrete external components are shared and available output currents sum together.