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FN6839.2

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ISL6334AR5368

VR11.1, 4-Phase PWM Controller with

Light Load Efficiency Enhancement and

Load Current Monitoring Features

The ISL6334AR5368 controls microprocessor core voltage

regulation by driving up to 4 interleaved synchronous-rectified

buck channels in parallel. This multiphase architecture results

in multiplying channel ripple frequency and reducing input and

output ripple currents. Lower ripple results in fewer

components, lower cost, reduced power dissipation, and

smaller implementation area.

Microprocessor loads can generate load transients with

extremely fast edge rates and requires high efficiency at light

load. The ISL6334AR5368 utilizes Intersil’s proprietary

Active Pulse Positioning (APP), Adaptive Phase Alignment

(APA) modulation scheme, active phase adding and

dropping to achieve and maintain the extremely fast

transient response with fewer output capacitors and high

efficiency from light to full load.

The ISL6334AR5368 is designed to be completely compliant

with Intel VR11.1 specifications. It accurately reports the load

current via IMON pin to the microprocessor, which sends an

active low PSI# signal to the controller at low power mode.

The controller then enters 1- or 2-phase operation with diode

emulation option to reduce magnetic core and switching

losses, yielding high efficiency at light load. After the PSI#

signal is de-asserted, the dropped phase(s) are added back

to sustain heavy load transient response and efficiency.

Today’s microprocessors require a tightly regulated output

voltage position versus load current (droop). The

ISL6334AR5368 senses the output current continuously by

utilizing patented techniques to measure the voltage across the

dedicated current sense resistor or the DCR of the output

inductor. The sensed current flows out of FB pin to develop the

precision voltage drop across the feedback resistor for droop

control. Current sensing circuits also provide the needed

signals for channel-current balancing, average overcurrent

protection and individual phase current limiting. An NTC

thermistor’s temperature is sensed via TM pin and internally

digitized for thermal monitoring and for integrated thermal

compensation of the current sense elements.

A unity gain, differential amplifier is provided for remote voltage

sensing and completely eliminates any potential difference

between remote and local grounds. This improves regulation

and protection accuracy. The threshold-sensitive enable input is

available to accurately coordinate the start-up of the

ISL6334AR5368 with any other voltage rail. Dynamic-VID™

technology allows seamless on-the-fly VID changes. The

offset pin allows accurate voltage offset settings that are

independent of VID setting.

Features

• Intel VR11.1 Compliant

• Proprietary Active Pulse Positioning (APP) and Adaptive

Phase Alignment (APA) Modulation Scheme

• Proprietary Active Phase Adding and Dropping with Diode

Emulation Scheme For High Light Load Efficiency

• Precision Multiphase Core Voltage Regulation

- Differential Remote Voltage Sensing

- ±0.5% Closed-loop System Accuracy Over Load, Line

and Temperature

- Bi-directional, Adjustable Reference-Voltage Offset

• Precision resistor or DCR Differential Current Sensing

- Accurate Load-Line (Droop) Programming

- Accurate Channel-Current Balancing

- Accurate Load Current Monitoring via IMON Pin

• Microprocessor Voltage Identification Input

- Dynamic VID™ Technology for VR11.1 Requirement

- 8-Bit VID, VR11 Compatible

• Average Overcurrent Protection and Channel Current Limit

• Precision Overcurrent Protection on IMON Pin

• Thermal Monitoring and Overvoltage Protection

• Integrated Programmable Temperature Compensation

• Integrated Open Sense Line Protection

• 1- to 4-Phase Operation, Coupled Inductor Compatibility

• Adjustable Switching Frequency up to 1MHz Per Phase

• Package Option

- QFN Compliant to JEDEC PUB95 MO-220 QFN - Quad

Flat No Leads - Product Outline

• Pb-Free (RoHS Compliant)

Data Sheet

September 7, 2010