U U
FEATURES
■ No Current Sense Resistors Required ■ Out-of-Phase Controllers Reduce Required
Input Capacitance ■ VOUT2...
U U
FEATURES
■ No Current Sense Resistors Required ■ Out-of-Phase Controllers Reduce Required
Input Capacitance ■ VOUT2 Tracks 1/2 VREF ■ Symmetrical Source/Sink Output Current
Capability (VOUT2) ■ Spread Spectrum Operation (When Enabled) ■ Wide VIN Range: 2.75V to 9.8V ■ Constant Frequency Current Mode Operation ■ 0.6V ±1.5% Voltage Reference (VOUT1) ■ Low Dropout Operation: 100% Duty Cycle ■ True PLL for Frequency Locking or Adjustment ■ Internal Soft-Start Circuitry ■ Power Good Output Voltage Monitor ■ Output Overvoltage Protection ■ Micropower Shutdown: IQ = 9μA ■ Tiny Low Profile (4mm × 4mm) QFN and Narrow
SSOP Packages
U APPLICATIO S
■ DDR, DDR II and QDR Memory ■ SSTL, HSTL Termination Supplies ■ Servers, RAID Systems ■ Distributed DC Power Systems
LTC3776
Dual 2-Phase, No RSENSETM, Synchronous Controller for DDR/QDR Memory Termination
DESCRIPTIO
The LTC®3776 is a 2-phase dual output synchronous stepdown switching
regulator controller for DDR/QDR memory termination applications. The second controller regulates its output voltage to 1/2 VREF while providing symmetrical source and sink output current capability.
The No RSENSE constant frequency current mode architecture eliminates the need for sense resistors and improves efficiency. Power loss and noise due to the ESR of the input capacitance are minimized by operating the two controllers out of phase.
The switching frequency can be programmed up to 750kHz, allowing the use of small surface mount inductors and capaci...