The LTC3618IUF#PBF 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 LTC3618IUF#PBF can be synchronized to an external clock up to 4MHz.
The LTC3618IUF#PBF is offered in leadless 24-pin 4mm × 4mm QFN and thermally enhanced 24-pin TSSOP packages.
Feature
- 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
Applications
- DDR Memory
- Supports DDR, DDR2, and DDR3 Standards
- Tracking Supplies
