IR3088A

SYSTEM THEORY OF OPERATION

XPhase

The XPhase

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

control converters of any phase number 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 1, 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.

0.1uF

RCS

CCS

CIN

0.1uF

RCS

CCS

VOUT+

VOUT-

12V

VID3

VID4

VOUT SENSE+

VOUT SENSE-

VID0

VID2

VR HOT

ENABLE

VID1

VID5

PHASE FAULT

POWER GOOD

IR3081

CONTROL

IC

>> PHASE TIMING

>> PWM CONTROL

ADDITIONAL PHASES

INPUT/OUTPUT

>> BIAS VOLTAGE

IR3088A

PHASE IC

CONTROL BUS

<< CURRENT SENSE

CURRENT SHARE

CURRENT SHARE

>> VID VOLTAGE

PHASE FAULT

COUT

PHASE FAULT

PHASE HOT

IR3088 A

PHASE IC

PHASE HOT

Figure 1. System Block Diagram

Page 6 of 34