IR3502BMPBF International Rectifier, IR3502BMPBF Datasheet - Page 26

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IR3502BMPBF

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
Datasheet

Specifications of IR3502BMPBF

Package
32-Lead MLPQ
Circuit
X-Phase Control IC
Switch Freq (khz)
250kHz to 1.5MHz
Pbf
PbF Option Available
DESIGN PROCEDURES - IR3502B AND IR3507 CHIPSET
IR3502B EXTERNAL COMPONENTS
Oscillator Resistor Rosc
The oscillator of IR3502B generates square-wave pulses to synchronize the phase ICs. The switching frequency
of the each phase converter equals the PHSOUT frequency, which is set by the external resistor R
to the curve in Figure 18. The CLKOUT frequency equals the switching frequency multiplied by the phase
number. The Rosc sets the reference current used for no load offset which is given by Figure 19 and equals:
Soft Start Capacitor C
The soft start capacitor C
start time, VID sample delay time, VR ready delay time and over-current fault latch delay time after VR ready.
For the converter using VID with boot voltage, the SS/DEL pin voltage controls the slew rate of the converter
output voltage, as shown in Figure 9. After the ENABLE pin voltage rises above 0.85V, there is a soft-start delay
time TD1
time TD2 represents the time during which converter voltage rises from zero to 1.1V
(TD3) is the time period when VID stays at boot voltage of 1.1V. VID rise or fall time (TD4) is the time when VID
changes from boot voltage to the final voltage. The VR ready delay time (TD5) is the time period from VR
reaching the final voltage to the VR ready signal being issued, which is determined by the delay comparator
threshold.
C
SS/DEL
= 0.1uF meets all the specifications of TD1 to TD5, which are determined by (2) to (6) respectively.
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after which the error amplifier output is released to allow the soft start of output voltage. The soft start
SS/DEL
SS/DEL
TD
TD
TD
5
programs five different time parameters. They include soft start delay time, soft
4
3
C
C
TD
TD
C
SS
SS
SS
/
1
DEL
2
/
/
ISETPT
DEL
DEL
I
( *
CHG
C
C
I
*
. 3
SS
*
CHG
SS
I
3 (
92
CHG
V
/
I
/
I
DEL
CHG
DAC
DEL
CHG
1
) 3
4 .
. 0
Rosc
1 *
1 *
595
1
4 .
TD
1
1 .
1 .
) 1 .
4
C
C
52
C
52
SS
C
SS
C
SS
52
5 .
52
SS
/
5 .
SS
/
DEL
/
DEL
/
*
5 .
5 .
/
DEL
*
DEL
52
DEL
10
10
*
*
1 *
5 .
10
10
*
1 *
*
*
6
. 0
*
4 .
6
0
V
1 .
10
6
92
6
7 .
DAC
6
TD
.
The VID sample delay time
1
4
1 .
IR3502B
OSC
V3.2
according
(1)
(2)
(3)
(4)
(5)
(6)

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