ncp5392p ON Semiconductor, ncp5392p Datasheet - Page 23

• Manufacturer Part Number: ncp5392p
• Description: 2/3/4-phase Controller For Cpu Applications
• Manufacturer: ON Semiconductor

internally mirrored into a capacitor to create an oscillator.
The period is proportional to the resistance and frequency
is inversely proportional to the total resistance. The total
resistance may be estimated by Equation 1. This equation
is valid for the individual phase frequency in both three and
four phase mode.
divider connected to Rosc pin, thus,
A
DRP
I1
I2
I3
I4
For multiphase controller, the ripple current can be calculated as,
Therefore calculate the current limit voltage as below,
In Equation 4, A
As introduced before, V
Ilim
60
50
40
30
20
10
0
100
+ *
+
V
A
Acssum
Calculation
Real
LIMIT
CSSUM
(R
Figure 11. ROSC vs. Frequency
Figure 12. ACSSUM and ADRP
NOR
R
30.5 kW ^ 20947
R
+ 2 V @
osc
NOR
+ *4
) R
CSSUM
RISO1
^ 20947
RSUM
@ (R
ISO1
R
Freq-kHz
LIM1
ISO1
and A
) R
V
V
LIMIT
R
Adrp
LIMIT
LIMIT
RNOR
+
LIM2
) R
-
) R
RT2
ISO2
F
DRP
SW
^ A
^ A
LIM2
ISO2
comes from a resistor
) R
330
are the gain of current summing amplifier and droop amplifier.
*1.1262
CSSUM
CSSUM
@ COEpsi
) R
*1.1262
RISO2
T2
+
-
) @ R
T2
@ A
@ A
)
SUM
Ipp +
DRP
DRP
OCP
event
http://onsemi.com
(eq. 1)
(eq. 5)
(eq. 6)
@ DCR
@ DCR
(V
1000
NCP5392P
in
* N @ V
L @ F
Tmax
Tmax
23
SW
current of all phases multiplied by a controlled gain
(Acssum*Adrp). DCR sensed inductor current is a function
of the winding temperature. The best approach is to set the
maximum current limit based on expected average
maximum temperature of the inductor windings,
@ (I
@ I
temperature sense resistor placed near inductor. R
the resistor connecting between pin VDFB and pin
CSSUM. If PSI = 1, PSI function is off, the current limit
follows the Equation 7; if PSI = 0, the power saving mode
will be enabled, COEpsi is a coefficient for the current
limiting related with power saving function (PSI), the
current limit can be calculated from Equation 8. COEpsi
value is one over the original phase count N. Refer to the
PSI and phase shedding section for more details.
DCR
out
@ V
The current limit function is based on the total sensed
R
MIN_OCP
) @ V
ISO1
MIN_OCP
in
Tmax
out
and R
+ DCR
@ ) 0.5 @ Ipp)
@ ) 0.5 @
ISO2
25C
are in series with R
(V
(1 ) 0.00393 @ (T
in
* N @ V
L @ F
SW
out
@ V
) @ V
in
max
out
* 25))
T2
, the NTC
(eq. 3)
(eq. 4)
SUM
(eq. 2)
is