IR3080

PbF

6

6

/

/

/

/

10

*

70

)

10

*

70

3

.

1

(

*

)

*

3

.

1

(

*

−

−

∗

−

=

−

=

DEL

SS

DEL

SS

CHG

CHG

DEL

SS

DEL

SS

SSDEL

R

C

I

I

R

C

t

shown in Figure15.

DOWN

SINK

VDAC

SR

I

C

=

(8)

2

15

10

2

.

3

5

.

0

VDAC

VDAC

C

R

−

∗

+

=

(9)

VDAC

SOURCE

UP

C

I

SR

=

(10)

The inductor DC resistance is utilized to sense the inductor current. The copper wire of inductor has a constant

temperature coefficient of 3850 ppm/°C, and therefore the maximum inductor DCR can be calculated from Equation

)]

(

10

*

3850

1

[

_

6

_

_

ROOM

MAX

L

ROOM

L

MAX

L

T

T

R

R

−

∗

+

∗

=

−

(11)

The current sense amplifier gain of IR3086A decreases with temperature at the rate of 1470 ppm/°C, which

compensates part of the inductor DCR increase. The phase IC die temperature is only a couple of degrees Celsius

higher than the PCB temperature due to the low thermal impedance of MLPQ package. The minimum current sense

)]

(

10

*

1470

1

[

_

6

_

_

ROOM

MAX

IC

ROOM

CS

MIN

CS

T

T

G

G

−

∗

−

∗

=

−

(12)

−

−

+

+

∗

−

∗

+

=

CS

CSIN

CS

CSIN

OFST

CS

TOFST

CS

R

I

R

I

V

V

_

_

(13)

phase and is calculated from Equation (15).

OCSET

MIN

CS

TOFST

CS

P

MAX

L

LIMIT

OCSET

I

G

V

K

R

n

I

R

/

]

)

1

(

[

_

_

_

+

+

∗

∗

=

(14)

n

I

f

V

L

V

V

V

K

O

SW

I

O

O

I

P

/

)

2

/(

)

(

∗

∗

∗

∗

−

=

(15)

Page 21