1

Multiphase PWM Regulator for VR12 DDR Memory

Systems

ISL6353

The ISL6353 is a three-phase PWM buck regulator controller for

VR12 DDR memory applications. The multi-phase implementation

results in better system performance, superior thermal

management, lower component cost and smaller PCB area.

The ISL6353 has two integrated power MOSFET drivers for

implementing a cost effective and space saving power

management solution.

The PWM modulator of the ISL6353 is based on Intersil’s Robust

PWM switching frequency during load transients, achieving faster

modulation operation in light load conditions to achieve higher light

load efficiency.

The ISL6353 is designed to be completely compliant with VR12

specifications. The ISL6353 has a serial VID (SVID) bus

communicating with the CPU. The output can be programmed for

1-, 2- or 3-phase interleaved operation. The output voltage and

power state can also be controlled independent of the serial VID

bus.

The ISL6353 has several other key features. It supports DCR

current sensing with a single NTC thermistor for DCR

temperature compensation or accurate resistor current sensing.

It also has remote voltage sense, adjustable switching frequency,

current monitor, OC/OV protection and power-good. Temperature

monitor and thermal alert is available too.

Features

• VR12 Serial Communications Bus

• Precision Voltage Regulation

- 5mV Steps with VID Fast/Slow Slew Rates

• Supports Two Current Sensing Methods

- Lossless Inductor DCR Current Sensing

- Precision Resistor Current Sensing

• Programmable 1, 2 or 3-Phase Operation

• Adaptive Body Diode Conduction Time Reduction

• Superior Noise Immunity and Transient Response

• Pin Programmable Output Voltage and Power State Mode

• Output Current Monitor and Thermal Monitor

• Differential Remote Voltage Sensing

• High Efficiency Across Entire Load Range

• Programmable Switching Frequency

• Resistor Programmable VBOOT, Power State Operation, SVID

• Excellent Dynamic Current Balance Between Phases

• OCP/WOC, OVP, OT Alert, PGOOD

• Small Footprint 40 Ld 5x5 TQFN Package

• Pb-Free (RoHS Compliant)

Applications

•DDR Memory

FIGURE 1. FAST TRANSIENT RESPONSE

FIGURE 2. ISL6353EVAL1Z EFFICIENCY vs LOAD

COMP

200mV/DIV

VDDQ = 1.5V

50mV/DIV

PHASE1/2/3

5V/DIV

1V/DIV

26A STEP LOAD

20µs/DIV

85

86

87

88

89

90

91

92

93

94

95

0

10

20304050607080

LOAD (A)

1.5V PS1 2ph CCM

1.5V PS0

1.5V PS2 1ph DE

1.35VPS0

1.35V PS1 2ph CCM

1.35VPS2 1ph DE

FN6897.0

September 15, 2011

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1-888-INTERSIL or 1-888-468-3774

Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.

All other trademarks mentioned are the property of their respective owners.