IR3504MPBF International Rectifier, IR3504MPBF Datasheet - Page 28

• Manufacturer Part Number: IR3504MPBF
• Description: IC CTRL XPHASE AMD SVID 32-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase3™r

Specifications of IR3504MPBF

• Applications: Processor
• Current - Supply: 10mA
• Voltage - Supply: 4.75 V ~ 7.5 V
• Operating Temperature: 0°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: *
• Package: 32-Lead MLPQ
• Circuit: X-Phase Control IC
• Switch Freq (khz): 250kHz to 1.5MHz
• Pbf: PbF Option Available
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

DESIGN PROCEDURES - IR3504 AND IR3505 CHIPSET
IR3504 EXTERNAL COMPONENTS
All the output components are selected using one output but suitable for both unless otherwise specified.
Oscillator Resistor R
The IR3504 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
determine the R
number.
Soft Start Capacitor C
The Soft Start capacitor C
ready delay time and over-current fault latch delay time after VR ready.
SS/DEL pin voltage controls the slew rate of the converter output voltage, as shown in Figure 11. Once the
ENABLE pin rises above 1.65V, there is a soft-start delay time TD1 during which SS/DEL pin is charged from
zero to 1.4V. Once SS/DEL reaches 1.4V the error amplifier output is released to allow the soft start. The soft
start time TD2 represents the time during which converter voltage rises from zero to pre-PWROK VID voltage and
the SS/DEL pin voltage rises from 1.4V to pre-PWROK VID voltage plus 1.4V. VR ready delay time TD3 is the
time period from VR reaching the pre-PWROK VID voltage to the VR ready signal being issued.
Calculate C
The soft start delay time TD1 and VR ready delay time TD3 are determined by equation (2) and (3) respectively.
Once C
Due to the exponential turn-on slope of the discharge current (47uA), a correction factor (X2.5) is added to the
equation (4) to accurately predict over-current delay time.
SS/DEL
Page 28
SS/DEL
is chosen, use equation (4) to calculate the maximum over-current fault latch delay time
ROSC
TD
TD
C
based on the required soft start time TD2.
SS
1
3
/
DEL
=
=
R
value. The CLKOUT frequency equals the switching frequency multiplied by the phase
SS/DEL
osc
C
C
t
OCDEL
=
SS/DEL
SS
SS
/
TD
/
V
I
DEL
DEL
CHG
pre
2
=
( *
−
1 *
programs four different time parameters, soft start delay time, soft start time, VR
*
PWROK
2
. 3
I
5 .
1 .
CHG
92
*
=
I
C
−
CHG
C
=
V
SS
50
SS
pre
TD
I
/
DEL
DISCHG
/
−
DEL
*
V
PWROK
2
10
pre
*
*
1 *
. 0
−
−
50
6
PWROK
13
−
1 .
*
1
10
) 1 .
=
2
−
=
6
5 .
C
*
SS
C
/
DEL
SS
47
/
DEL
( *
*
10
. 3
*
50
92
−
. 0
6
13
*
−
10
V
pre
−
6
(2)
−
PWROK
(1)
−
1
ROSC
) 1 .
July 28, 2009
, use Figure 2 to
IR3504
t
OCDEL.
(3)
(4)