IR3502BMPBF International Rectifier, IR3502BMPBF Datasheet - Page 28

• Manufacturer Part Number: IR3502BMPBF
• Description: The IR3502B control IC combined with an XPHASE3 Phase IC provides a full featured and flexible way to implement a complete VR11.0 and VR11.1 power solution.
• Manufacturer: International Rectifier

Specifications of IR3502BMPBF

• Package: 32-Lead MLPQ
• Circuit: X-Phase Control IC
• Switch Freq (khz): 250kHz to 1.5MHz
• Pbf: PbF Option Available

Droop Resistor
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 (15),
where R
respectively. After the thermal compensation is achieved using the procedure given above, the droop resistance
can be calculated using the following equation.
Over-current Threshold
No Load Output Voltage Setting Resistor R
A resistor between VSETPT pin and VDAC is used to create output voltage offset V
difference between V
I
Once the current report gain and the thermal compensation are calculated the OCP threshold is calculated using the
following expression.
VSETPT
is the current flowing out of VSETPT pin as shown in Figure 19.
L_tmax
Page 28 of 38
and R
DAC
L_room
RTHERM
voltage and output voltage at no load condition. R
I
C
are the inductor DCR at maximum temperature T
OCP
TH


RTHERM
1
3
RTCMP
R
R

B




t
t
TH
t
RTCMP
R
_
_
max
R
t
room
L
max
DRP
_

room
R
room
VSETPT
n

RTHERM
1





RTHERM





G




2
VSETPT
RTHERM
1
3
3
3
cs






  





B

K
K
R
K
K
R
TH



R
V
1
THERM
THERM
t
FB
c
c
_
o

O
,
1
I
_
_
t

room
t
VSETPT
max
_
(
t
max
room

RTCMP
max
NLOFST

 

_
_


room

G

B
room
room




 

2
R
TH
CS
RTHERM
RTHERM
t
_

. 1


) 2

t

e
2
1
max
17
R
1
1
II


n
R
THERM








L
(
t

4
_
RTCMP

_

1
1
t
room

RTCMP
ROOM
RTCMP
max
RTCMP
C
RTCMP

TH




t


273
max
RTHERM
R

  

1
t

1
_
1
T

room
1
max



RTHERM
3
3
3
VSETPT




1


273
t
max
max
RTCMP

R
1
T




 

room
t
and room temperature T
is determined by (26), where
_
room
_




room
3
O_NLOFST,



)



IR3502B
V3.2
which is the
(17)
(18)
(19)
(20)
(21)
(22)
(23)
room
.
(24)
(25)
(26)