IR3082A International Rectifier Corp., IR3082A Datasheet - Page 19

• Manufacturer Part Number: IR3082A
• Description: 9.6v Amd Xphasetm Control Ic
• Manufacturer: International Rectifier Corp.

DESIGN PROCEDURES – IR3082A AND IR3086A CHIPSET
IR3082A EXTERNAL COMPONENTS
Oscillator Resistor Rosc
The oscillator of IR3082A 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.
Soft Start Capacitor C
Because the capacitor C
delay time, and the frequency of hiccup mode, 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. After the
ENABLE pin voltage rises above 1.27V, there is a soft-start delay time t
is released to allow the soft start. The soft start time t
from zero to Vo. t
Once C
delay time t
and (5) respectively.
The hiccup mode duty cycle of over current protection is determined by the charge current I
current I
over-current set value.
SS/DEL
Page 19 of 33
DISCHG
VccPG
is chosen, the soft start delay time t
of C
C
t
t
t
VccPG
OCDEL
SS
SSDEL
from output voltage (Vo) in regulation to Power Good are fixed and shown in Equations (2), (3), (4)
SS
can be programmed by an external capacitor, which is determined by Equation (1).
/
SS/DEL
DEL
SS/DEL
C
C
C
SS/DEL
SS
SS
SS
I
and is fixed at 9%. However, the hiccup frequency is determined by the load current and
CHG
/
I
I
/
/
DEL
CHG
DISCHG
DEL
V
DEL
and Resistor R
O
˜
˜
t
˜
˜
SS
1
(
programs three different time parameters, i.e. soft start time, over current latch
. 0
. 3
I
3 .
CHG
11
83
55
.
C

V
SS
˜
C
55
10
O
V
SS
/
DEL
O
˜

5
10
/
6
1
DEL
˜
˜
10
) 3 .
t
˜
SS/DEL
SS
6
1
3 .
˜
6
. 0
11
C
SS
SSDEL
/
SS
DEL
represents the time during which the output voltage rises
˜
55
, the over-current fault latch delay time
(
. 3
˜
10
83

6
V
O

1
) 3 .
SSDEL,
after which the error amplifier output
(2)
(3)
05/02/2006
CHG
IR3082A
(1)
(4)
OSC
SS/DEL
t
OCDEL,
and discharge
according to
.
and the