ir3092 International Rectifier Corp., ir3092 Datasheet - Page 20

• Manufacturer Part Number: ir3092
• Description: 2 Phase Opteron, Athlon, Or Vr10.x Control Ic
• Manufacturer: International Rectifier Corp.

Soft-start delay time
allow the soft start. The soft start time
can be programmed by C
Once C
t
Over Current Protection (OCP)
The current limit threshold is set by a resistor connected between the OCSET and VDAC pins. If the average Current
Sense Amplifier output plus VDAC voltage exceeds the OCSET voltage, the over-current protection is triggered.
A delay is included if an over-current condition occurs after a successful soft-start sequence. This is required since over-
current conditions can occur as part of normal operation due to load transients or VID transitions. If an over-current fault
occurs during normal operation, the Over Current Comparator will initiate the discharge of the capacitor at SS/DEL but
will not set the fault latch immediately. If the over-current condition persists long enough for the SS/DEL capacitor to
discharge below the 250mV offset of the delay comparator, the Fault latch will be set pulling the Error Amplifier’s output
low inhibiting switching in the phase ICs and de-asserting the PWRGD signal. See Soft Start, Over-Current Fault Delay,
and Hiccup Mode.
The inductor DC resistance R
bias current of OCSET pin, is set by R
R
VccPG
OCSET
from output voltage (V
SS
Page 20 of 37
is defined in the following Equation (8).
is chosen, the soft start delay time
t
SSDEL
R
OCSET
SS
using equation (4).
is the time to charge SS/DEL up to 1.3V. After this the error amplifier output is released to
O
L
t
t
t
) in regulation to Power Good are fixed and shown in equation (5), (6) and (7) respectively.
VccPG
OCDEL
SSDEL
is utilized to sense the inductor current. I
(
I
C
LIMIT
2
SS
C
C
ROSC
C
t
SS
SS
I
SS
I
SS

I
DISCHG
CHG
I
CHG
*
represents the time during which converter voltage rises from zero to V
*
2
CHG
*
and is also determined by the curve in the Typical Operating Characteristics.
Vo
'
'
'
V
V
V
t
V
L
O
*
SSDEL,
(
t
Vin
SS
Vin
C
55
C
50
C
SS
SS

SS
*
*
the over-current fault latch delay time
5 .
55
Vo
( *
10
1 *
fsw
*
*
. 3
*
55
. 0
10
)
3 .
¢
6
10
75
)
25
V
*
£
6
O
¡
10

6
R
*
V
L
¤
6
t
O
SS
23

1
.
LIMIT
) 3 .
/ 5
I
OCSET
is the required over current limit. I
(4)
(5)
(6)
(7)
(8)
t
OCDEL
06/25/04
, and the delay time
IR3092
OCSET,
O.
t
the
SS