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LTC3618 - Dual 4MHz, ±3A Synchronous Buck Converter for DDR Termination

The LTC®3618 is a dual synchronous step-down regulator using a current mode, constant-frequency architecture. It provides a complete DDR solution with an input voltage range from 2.25V to 5.5V.

The output of the first step-down regulator offers a high accuracy VDDQ supply. A buffered reference generates VTTR at 50% of VDDQIN and drives loads up to ±10mA. The second regulator generates the DDR termination voltage (VTT) equal to VTTR. Both regulators are capable of delivering ±3A of load current at 1MHz switching frequency.

The operating frequency is externally programmable up to 4MHz, allowing the use of small surface mount inductors. 0°, 90°, or 180° of phase shift between the two channels can be selected to minimize input current ripple. For switching noise-sensitive applications, the LTC3618 can be synchronized to an external clock up to 4MHz.

The LTC3618 is offered in leadless 24-pin 4mm × 4mm QFN and thermally enhanced 24-pin TSSOP packages.

Features DDR Power Supply, Termination and Reference High Efficiency: Up to 94% Dual Outputs with ±3A Output Current Capability 2.25V to 5.5V Input Voltage Range ±1% Output Voltage Accuracy VTT Output Voltage Down to 0.5V Shutdown Current ≤1μA VTTR = VDDQIN/2, VFB2 = VTTR Adjustable Switching Frequency Up to 4MHz Internal or External Compensation Selectable 0°/90°/180° Phase Shift Between Channels Internal or External Soft-Start for VDDQ, Internal Soft-Start for VTT Power Good Status Outputs Low Profile 4mm × 4mm QFN-24 and TSSOP-24 Packages Typical Application

Applications DDR Memory Supports DDR, DDR2, and DDR3 Standards Tracking Supplies Packaging

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