LTC3776 Series

Dual 2-Phase, No RSENSE™,Synchronous Controller for DDR/QDR Memory Termination

Catalog

Dual 2-Phase, No RSENSE™,Synchronous Controller for DDR/QDR Memory Termination

Part	Package / Case	Package / Case [custom]	Voltage - Output [Min]	Voltage - Output [Max]	Mounting Type	Operating Temperature [Max]	Operating Temperature [Min]	Number of Outputs	Applications	Supplier Device Package	Voltage - Input [Min]	Voltage - Input [Max]
Analog Devices LTC3776EGN#TRPBF	24-SSOP	0.154 " 3.9 mm	0.3 V	9.8 V	Surface Mount	85 °C	-40 °C	2	Controller DDR QDR	24-SSOP	2.75 V	9.8 V
Analog Devices LTC3776EUF#TRPBF	24-WFQFN Exposed Pad		0.3 V	9.8 V	Surface Mount	85 °C	-40 °C	2	Controller DDR QDR	24-QFN (4x4)	2.75 V	9.8 V
Analog Devices LTC3776EGN#PBF	24-SSOP	0.154 " 3.9 mm	0.3 V	9.8 V	Surface Mount	85 °C	-40 °C	2	Controller DDR QDR	24-SSOP	2.75 V	9.8 V

Catalog

Dual 2-Phase, No RSENSE™,Synchronous Controller for DDR/QDR Memory Termination

Key Features

• No Current Sense Resistors Required

• Out-of-Phase Controllers Reduce Required Input Capacitance

• VOUT2Tracks 1/2 VREF

• Symmetrical Source/Sink Output Current Capability (VOUT2)

• Spread Spectrum Operation (When Enabled)

• Wide VINRange: 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

Description

The LTC3776 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 VREFwhile providing symmetrical source and sink output current capability.The No RSENSEconstant 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 capacitors. For noise sensitive applications, the LTC3776 switching frequency can be externally synchronized from 250kHz to 850kHz, or can be enabled for spread spectrum operation. Forced continuous operation reduces noise and RF interference. Soft-start for VOUT1is provided internally and can be extended using an external capacitor.The LTC3776 is available in the tiny thermally enhanced (4mm × 4mm) QFN package or 24-lead SSOP narrow package.Protected by U.S. Patents including 5481178, 5929620, 6144194, 6580258, 6304066, 6611131, 6498466, patent pending on Spread Spectrum.ApplicationsDDR, DDR II and QDR MemorySSTL, HSTL Termination SuppliesServers, RAID SystemsDistributed DC Power Systems