IR3502BMPBF International Rectifier, IR3502BMPBF Datasheet - Page 29

• 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

Thermistor R
The threshold voltage of VRHOT comparator is fixed at 1.6V, and a negative temperature coefficient (NTC)
thermistor R
thermistor resistance at allowed maximum temperature T
Select the series resistor R
operational temperature range. Then calculate R
TMAX from (28).
VCCL Capacitor C
driven. The linear regulator supplies the bias and gate drive current of the phase ICs. A 4.7uF normally ensures
stable VCCL performance for Intel VR11.1 applications.
VCCL Regulator Drive Resistor R
minimum input voltage requirements. The following equation gives an estimate of the average load current of
the switching phase ICs.
Q
VCCL, the maximum R
Due to limited pull down capability of the VCCLDRV pin, make sure the following condition is satisfied.
In the above equation, V
above condition is not satisfied there is a need to use a device with higher β
be used instead of a single NPN transistor.
Current Monitor Filter
A filter is added to isolate the CPU from rapid changes in the load current and trigger false response. A filter with
300 us time constant provides adequate delay for Intel VR11.1 response. A 1k resistor between IMON and local
ground helps equalize the source and sink current of the IMON pin.
The capacitor is selected based on the stability requirement of the linear regulator and the load current to be
The drive resistor is primarily dependent on the load current requirement of the linear regulator and the
gb
and Q
Page 29 of 38
gt
HOTSET3
are the gate charge of the top and bottom FET. For a minimum input voltage and a maximum
HOTSET3
VCCL
is required to sense the temperature of the power stage. If we pre-select R
R
and Over Temperature Setting Resistors R
VCCLDRV
TMAX
I
( min) and V
HOTSET2

required to use the full pull-down current of the VCCL driver is given by
R
I
HOTSET
drive
VCCLDRV
V
to linearize the NTC thermistor, which has non-linear characteristics in the
R
R
I
(max)
_
I
VCCLDRV
( max) is the minimum and maximum anticipated input voltage. If the
HOTSET
avg
3
*
R

EXP
VCCLDRV
1


(

Q
0

7 .
(
gb
[
V
R
HOTSET1
B

I
TMAX

(min)
HOTSET
6
I
Q
drive
8 .
V
gt
MAX

)
_


R
avg

corresponding to the allowed maximum temperature
3
HOTSET
0
10
( *
f
is calculated from (27).
sw
7 .
/
mA

T


1
min
L
6 .
6
2
10
_
1
)
8 .
HOTSET1
MAX
( *
mA
V
VCCL



n
min
T
and R
_
or Darlington configuration can
ROOM

1
. 1
) 6
HOTSET2
)]
IR3502B
HOTSET3
V3.2
, the NTC
(29)
(30)
(31)
(27)
(28)