IR3086

Page 13 of 15

9/1/03

The IR3086 has the ability to detect if a phase stops switching and can provide this information to the system through

the PHSFLT output pin. If a phase stops switching its output current will drop to zero and the output of its IR3086

current sense amp will be the DACIN voltage. The Share Adjust Amplifier reacts to this by increasing the Ramp Slope

Adjust current until it exceeds the externally programmable PWM Ramp bias current. This will cause the voltage at the

PWMRMP pin to drop below its normal operating range. The Fault Comparator trips and drives the PHSFLT output to

ground when the voltage on the PWMRMP pin falls below 91% of the DACIN voltage. PHSFLT is an open-collector

output and should be pulled up to a voltage source through a resistor.

APPLICATIONS INFORMATION

RVFB

0.1uF

CCS+

RCS+

0.1uF

CIN

IR3086

PHASE

IC

RMPIN+

1

RMPIN-

2

GATEH

14

VCCH

15

HOTSET

3

VRHOT

4

PGND

13

GATEL

12

ISHARE

5

VCCL

11

POWERGOOD

PHASE FAULT

VRHOT

VOUT-

VOUT SENSE-

VOUT SENSE+

VOUT+

RVDRP

DISTRIBUTION

IMPEDANCE

COUT

0.1uF

CCS+

0.1uF

RBIASIN

IR3086

PHASE

IC

RMPIN+

1

RMPIN-

2

GATEH

14

VCCH

15

HOTSET

3

VRHOT

4

PGND

13

GATEL

12

ISHARE

5

VCCL

11

0.1uF

CCS-

RCS-

RPWMRMP

CSCOMP

10

RCS+

0.1uF

0.1uF

CCS+

RCS-

RBIASIN

IR3086

PHASE

IC

RMPIN+

1

RMPIN-

2

GATEH

14

VCCH

15

HOTSET

3

VRHOT

4

PGND

13

GATEL

12

ISHARE

5

VCCL

11

10

0.1uF

CCS-

RPWMRMP

CSCOMP

RCS+

RBIASIN

RCS-

CCS-

0.1uF

CCS+

0.1uF

IR3086

PHASE

IC

RMPIN+

1

RMPIN-

2

GATEH

14

VCCH

15

HOTSET

3

VRHOT

4

PGND

13

GATEL

12

ISHARE

5

VCCL

11

CCS-

RCS-

RBIASIN

RPWMRMP

CSCOMP

10

0.1uF

RCS+

CSCOMP

10

0.1uF

RPWMRMP

0.1uF

0.1uF

IR3086

PHASE

IC

RMPIN+

1

RMPIN-

2

GATEH

14

VCCH

15

HOTSET

3

VRHOT

4

PGND

13

GATEL

12

ISHARE

5

VCCL

11

CCS+

CCS-

RCS-

RBIASIN

CSCOMP

10

0.1uF

RCS+

RPWMRMP

RSHARE

CVDAC

RVDAC

0.1uF

ROSC

RVFB

10

ROCSET

RVDRP

IR3081

CONTROL

IC

OSCDS

1

VID5

2

VID0

3

VID1

4

VID2

5

VID3

6

VID4

7

VBIAS

21

BBFB

20

EAOUT

19

FB

18

VDRP

17

IIN

16

OCSET

15

0.1uF

12V

VID3

VID4

VID1

VID5

ENABLE

VID2

VID0

Figure 7 – 5 Phase IR3081/3086 EVRD10 Converter