Features

• Wide V_IN Range: 3.1V to 60V
• Wide V_OUT Range: 0V to (V_IN – 0.5V)
• Single Resistor V_OUT Programming
• Integrated 110mΩ Top N-Channel/50mΩ Bottom N-Channel MOSFETs
• 95% Efficiency with 12V_IN and 5V_OUT
• Regulated I_Q: 440μA, Shutdown I_Q: 18μA
• Accurate Current Monitoring (±4%) without Sense Resistor
• Accurate Resistor Programmable Frequency (300kHz to 3MHz) with ±50% Frequency Sync Range
• Accurate Programmable Output Current
• Input Voltage Regulation for MPPT Applications
• ±0.8% Output Voltage Accuracy
• Peak Current Mode Operation
• Programmable Wire Drop Compensation
• Burst Mode® Operation, Forced Continuous Mode
• Internal Compensation and Programmable Soft-Start
• Overtemperature Protection
• Available in Thermally Enhanced 28-Lead (4mm × 5mm) QFN and TSSOP Packages

Typical Application

Description

The LTC®3649 is a high efficiency 60V, 4A synchronous monolithic step-down regulator. The regulator features a single resistor programmable output voltage, internal compensation and high efficiencies over a wide V_OUT range.

The step-down regulator operates from an input voltage range of 3.1V to 60V and provides an adjustable rail-to-rail output range from (V_IN – 0.5V) to ground while delivering up to 4A of output current. The switching frequency is also adjusted with an external resistor. A user-selectable mode input is provided to allow the user to trade off ripple noise for efficiency at light loads; Burst Mode operation provides the highest efficiency at light loads, while forced continuous mode provides low output ripple. The MODE/ SYNC pin can also be used to allow the user to synchronize the switching frequency to an external clock.

The LTC3649 operates with a peak current mode architecture that allows for fast transient response with inherent cycle-to-cycle current limit protection. It also features programmable output current limit, current monitoring and input voltage regulation.