IR3082

Page 6 of 6

12/17/04

SYSTEM THEORY OF OPERATION

XPhase

The XPhase

requiring small size, design flexibility, low voltage, high current, and fast transient response. The architecture can

be used in any multiphase converter ranging from 1 to 16 or more phases where flexibility facilitates the design

trade-off of multiphase converters. The scalable architecture can be applied to other applications which require

high current or multiple output voltages.

As shown in Figure 2, the XPhase

each using a single Phase IC. The Control IC communicates with the Phase ICs through a 5-wire analog bus, i.e.

bias voltage, phase timing, average current, error amplifier output, and VID voltage. The Control IC incorporates all

the system functions, i.e. VID, PWM ramp oscillator, error amplifier, bias voltage, and fault protections etc. The

Phase IC implements the functions required by the converter of each phase, i.e. the gate drivers, PWM comparator

and latch, over-voltage protection, and current sensing and sharing.

There is no unused or redundant silicon with the XPhase

controller that can be configured for 2, 3, or 4 phase operation. PCB Layout is easier since the 5 wire bus

eliminates the need for point-to-point wiring between the Control IC and each Phase. The critical gate drive and

current sense connections are short and local to the Phase ICs. This improves the PCB layout by lowering the

parasitic inductance of the gate drive circuits and reducing the noise of the current sense signal.

RCS

CCS

IR3086

PHASE

IC

CURRENT SHARE

CIN

VDD_CORE

12V

-SEN

GND

VID3

VID0

VID4

+SEN

VID2

POWER GOOD

VID1

>> BIAS VOLTAGE

>> VID VOLTAGE

<< CURRENT SENSE

>> PHASE TIMING

ADDITIONAL PHASES

COUT

IR3082

CONTROL

IC

>> PWM CONTROL

INPUT/OUTPUT

CONTROL BUS

ENABLE

RCS

CCS

IR3086

PHASE

IC

CURRENT SHARE

VR HOT

PHASE FAULT

Figure 2 – System Block Diagram