ir3500a International Rectifier Corp., ir3500a Datasheet - Page 37

• Manufacturer Part Number: ir3500a
• Description: Xphase3 Vr11.0 & Amd Pvid Control Ic
• Manufacturer: International Rectifier Corp.

No Load Output Voltage Setting Resistor R
From Figure 24, the bias current of VSETPT pin is 11.9uA with R
VCCL Programming Resistor R
Choose VCCL=7V to maximize the converter efficiency. Pre-select R
VCCL Drive Resistor R
The maximum drive current for the linear regulator is dependent on the type of MosFET used. For this
example its assumed that IR6622/ IRF6691 are used as buck switches.
The minimum input voltage is assumed to be 10 V and VCCL is fixed at 6.5V for this design.
Assuming the maximum input voltage to as 14 V,
Thermistor R
Choose NTC thermistor R
resistance at the allowed maximum temperature T
Select R
range. Then calculate R
R
VOLTAGE LOOP COMPENSATION
Type II compensation is used for the converter with Polymer output capacitors. Choose the crossover frequency
fc=25kHz, which is 1/10 of the switching frequency per phase, and determine Rcp and C
Pre-select R
R
R
R
R
HOTSET1
TMAX
VSETPT
VCCLFB
HOTSET
=
2
1
Page 37 of 47
HOTSET2
=
R
=
=
=3.65k .
THERM
R
V
VCCL
VCCLFB
(
FB
CS
I
R
THERM
VSETPT
=2.00k , and calculate R
TMAX
_
*
TOFST
−
1
= 931 to linearize the NTC, which has non-linear characteristics in the operational temperature
EXP
*
. 1
. 1
19
+
19
and Over Temperature Setting Resistors R
[
R
B
=
=
HOTSET1
THERM
HOTSET
VCCLDRV
I
11
20
drive
10
*
7
9 .
THERM
14
1
10
R
_
−
*
6 .
( *
2
avg
VCCLDRV
V
*
. 1
3
10
)
*
1
10
19
−
T
( *
corresponding to the allowed maximum temperature TMAX.
. 1
8 .
=
VCCLFB1
L
0
−
19
k
=2.2k , which has a constant of B
7 .
_
3
[
VCCL
−
Ω
1
(
MAX
6
47
−
=
=
=
6
. 4
10
n
5 .
DRP
−
840
05
+
V
=
T
and R
−
k
11
75
−
3
_
Ω
, R
. 1
mA
ROOM
Ω
0
n
mA
1
VSETPT
7 .
) 6
)
CP
, choose R
⋅
V
<
VCCLFB2
250
/
10
=
−
50
)]
and C
MAX
mA
6
(
=
k
142
5 .
and Adaptive Voltage Positioning Resistor R
2
V
+
is,
2 .
10
CP
=
*
+
10
1
VSETPT
mA
.
931
8 .
3
k
1
]
*
Ω
⋅
6 .
* )
EXP
3
OSC
=
=825 .
7 (
HOTSET1
[
75
3520
−
=50k .
VCCLFB1
mA
. 1
) 6
( *
THERM
273
and R
=
=20k , and calculate R
. 3
(20)
(21)
(19)
1
+
63
=3520, and the NTC thermistor
115
HOTSET2
k
Ω
−
273
,
CP
1
+
.
25
)]
July 3, 2008
=
142
IR3500A
Ω
VCCLFB2.
DRP
choose