Dual 4MHz, ±3A
Synchronous Buck Converter
for DDR Termination
n DDR Power Supply, Termination and Reference
n High Efficiency: Up to 94%
n Dual Outputs with ±3A Output Current Capability
n 2.25V to 5.5V Input Voltage Range
n ±1% Output Voltage Accuracy
n VTT Output Voltage Down to 0.5V
n Shutdown Current ≤1µA
n VTTR = VDDQIN/2, VFB2 = VTTR
n Adjustable Switching Frequency Up to 4MHz
n Internal or External Compensation
n Selectable 0°/90°/180° Phase Shift Between Channels
n Internal or External Soft-Start for VDDQ, Internal
Soft-Start for VTT
n Power Good Status Outputs
n Low Profile 4mm × 4mm QFN-24 and TSSOP-24
n DDR Memory
n Supports DDR, DDR2, and DDR3 Standards
n Tracking Supplies
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 volt-
age (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.
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 5481178, 6498466, 6580258, 6611131.
SVIN PVIN1 PVIN2
Efficiency and Power Loss vs Load Current
VDDQ = 1.8V
VTT = 0.9V
LOAD CURRENT (A)
For more information www.linear.com/LTC3618