IR3088AMTRPBF International Rectifier, IR3088AMTRPBF Datasheet - Page 14

• Manufacturer Part Number: IR3088AMTRPBF
• Description: IC XPHASE W/FAULT DET 20L-MLPQ
• Manufacturer: International Rectifier
• Series: XPhase™r

Specifications of IR3088AMTRPBF

• Applications: Processor
• Current - Supply: 10mA
• Voltage - Supply: 8.4 V ~ 14 V
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 20-MLPQ
• Pin Count: 20
• Mounting: Surface Mount
• Package Type: MLPQ
• Case Length: 4mm
• Case Height: 0.88mm
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: IR3088AMTRPBF; IR3088AMTRPBFTR

DESIGN PROCEDURES - IR3081A AND IR3088A CHIPSET
IR3081A EXTERNAL COMPONENTS
Oscillator Resistor Rosc
The oscillator of IR3081A generates a triangle waveform to synchronize the phase ICs, and the switching frequency
of the each phase converter equals the oscillator frequency, which is set by the external resistor R
the curve in Figure 13 of IR3081A Data Sheet.
Soft Start Capacitor C
Because the capacitor C
over-current latch delay time, and power good delay time, they should be considered together while choosing
C
The SS/DEL pin voltage controls the slew rate of the converter output voltage, as shown in Figure 10 of IR3081A
data sheet. After the ENABLE pin voltage rises above 0.6V, there is a soft-start delay time
error amplifier output is released to allow the soft start. The soft start time
converter voltage rises from zero to V
Equation (1).
Once C
delay time
and (4) respectively.
VDAC Slew Rate Programming Capacitor C
The slew rate of VDAC down-slope SR
Equation(5), where I
R
SR
of VDAC pin as shown in Figure15 of IR3081A Data Sheet.
SS/DEL
VDAC
UP
Page 14 of 33
is proportional to that of VDAC down-slope and is given by Equation (7), where I
is used to compensate VDAC circuit and is determined by Equation (6). The slew rate of VDAC up-slope
SS/DEL
.
t
VccPG
is chosen, the soft start delay time
from output voltage (V
SINK
C
t
t
t
C
R
SR
OCDEL
VccPG
SSDEL
VDAC
VDAC
SS
UP
SS/DEL
/
DEL
is the sink current of VDAC pin as shown in Figure 15 of IR3081A Data Sheet. The resistor
SS/DEL
=
=
=
=
=
=
I
C
C
0
=
C
C
SR
SOURCE
SS
5 .
SS
VDAC
I
SS
I
SINK
I
DOWN
CHG
/
+
/
I
OCDISCHG
/
DEL
DEL
programs four different time parameters, i.e. soft start delay time, soft start time,
CHG
DEL
3
V
2 .
C
O
*
*
1 *
VDAC
*
∗
t
3 (
SS
. 0
10
3 .
O.
8 .
115
DOWN
−
I
=
=
2
−
t
O
15
CHG
SS
) in regulation to Power Good are fixed and shown in Equations (2), (3)
70
C
. 0
=
SS
065
70
can be programmed by an external capacitor, which is determined by
*
C
/
VDAC
10
DEL
*
can be programmed by the external capacitor C
SS
V
−
10
40
−
O
/
V
6
DEL
1 *
−
O
*
6
*
and Resistor R
t
10
−
SSDEL,
3 .
t
*
SS
1
. 0
−
) 3 .
6
115
=
the over-current fault latch delay time
C
SS
/
DEL
( *
VDAC
70
. 3
*
735
10
−
−
6
V
t
O
SS
−
1
represents the time during which
) 3 .
IR3088APbF
SOURCE
t
May 18, 2009
(1)
(2)
(3)
(4)
(5)
(6)
(7)
SSDEL,
is the source current
VDAC
OSC
t
OCDEL
after which the
as defined in
according to
, and the