LTC3617

1

3617fa

Features

applications

Description

±6A Monolithic Synchronous

Step-Down Regulator

for DDR Termination

buckregulatorutilizingacurrentmode,constantfrequency

architecture. It operates from an input voltage range of

2.25V to 5.5V and provides a regulated output voltage

equal to 0.5 • VDDQIN while sourcing and sinking up to

6A of load current. An internal amplifier provides a VTTR

output voltage equal to 0.5 • VDDQIN with an output cur-

rent capability of ±10mA.

The operating frequency is externally programmable up to

4MHz, allowing the use of small surface mount inductors.

For switching-noise-sensitive applications, the LTC3617

can be synchronized to an external clock up to 4MHz.

ForcedcontinuousmodeoperationintheLTC3617reduces

noise and RF interference. Adjustable external compensa-

tion allows the transient response to be optimized over a

wide range of loads and output capacitors.

The internal synchronous switch increases efficiency and

eliminatestheneedforanexternalcatchdiode,minimizing

external component count and board space. The LTC3617

is offered in a leadless 24-pin 3mm

× 5mm thermally

enhanced QFN package.

L

, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks

of Linear Technology Corporation. All other trademarks are the property of their respective

owners. Protected by U.S. Patents, including 6580258, 5481178, 6498466, 6611131.

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±6A Output Current

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2.25V to 5.5V Input Voltage Range

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±10mV Output Voltage Accuracy

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Optimized for Low Output Voltages Down to 0.5V

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High Efficiency

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Integrated Buffer for VTTR = VDDQIN • 0.5

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Shutdown Current: <1µA

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Adjustable Switching Frequency: Up to 4MHz

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Optional Internal Compensation

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Internal Soft-Start

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Power Good Status Output

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Input Overvoltage Protected

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Thermally Enhanced 24-Pin 3mm

× 5mm

QFN Package

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DDR Termination

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Supports DDR, DDR2 and DDR3 Standards

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Tracking Supplies

typical application

Efficiency and Power Loss

vs Load Current

LOAD CURRENT (A)

30

90

100

20

10

80

50

70

60

40

0.1

1

10

3617 TA01b

0

1

10

0.1

0.01

0.1µF

1.25V

±10mA

RUN

VDDQIN

RT

PGOOD

ITH

SGND

PGND

2.5V

VTTR

LTC3617

SW

0.15µH

3617 TA01a

22µF

×4

SYNC

47µF

×2

VTT

1.25V

±6A