Dual 4MHz, 3A Synchronous Step-Down DC/DC Converter
FEATURES
■ High Effi ciency: Up to 94%
■ Dual Outputs with 2 × 3A Output Current Capability
■ Low Output Ripple Burst Mode® Operation: IQ = 130μA
■ 2.25V to 5.5V Input Voltage Range
■ ±1% Output Voltage Accuracy
■ Output Voltages Down to 0.6V
■ Programmable Slew Rate at Switch Pins
■ Low Dropout Operation: 100% Duty Cycle
■ Shutdown Current ≤1μA
■ Adjustable Switching Frequency Up to 4MHz
■ Internal or External Compensation
■ Selectable Pulse-Skipping/Forced Continuous/Burst Mode Operation with Adjustable Burst Clamp
■ Optional Active Voltage Positioning (AVP) with Internal Compensation
■ Selectable 0°/90°/180° (LTC3615) or selectable 140°/180° (LTC3615-1) Phase Shift Between Channels
■ Fixed Internal and Programmable External Soft-Start
■ Accurate Start-Up Tracking Capability
■ DDR Memory Mode IOUT = ±1.5A
■ Available in 4mm × 4mm QFN-24 and eTSSOP-24 Packages

APPLICATIONS
■ Point-of-Load Supplies
■ Distributed Power Supplies
■ Portable Computer Systems
■ DDR Memory Termination
■ Handheld Devices

D€SCRIPTION
The LTC®3615/LTC3615-1 are dual ЗА synchronous step-down regulators using acurrent mode, constant-frequency architecture. The DC supply current is only 130рА (Burst Mode operation at no-load) while maintaining the output voltages, dropping to zero current in shutdown. The 2.25V to 5.5V input supply range makes the parts ideally suited for single Li-Ion applications. 100% duty cycle capability provides low dropout operation, which extends operating time in battery-operated systems.
The operating frequency is externally programmable up to 4MHz, allowing the use of small surface mount inductors. 0°, 90°, or 180° (LTC3615) or 1407180° (LTC3615-1) of phase shift between the two channels can be selected to minimize input current ripple and outputvoltage ripple in a dual ЗА or single 6A output configuration. Programmable slew rate limiting reduces EMI, and external synchronization can be applied upto4MHz.
The internal synchronous switches increase efficiency and eliminate the need for external catch diodes, saving external components and board space.
The LTC3615/LTC3615-1 are offered in leadless 24-pin 4mm x 4mm QFN and thermally enhanced 24-pin eTSSOP packages.