NCP5331_05 ONSEMI [ON Semiconductor], NCP5331_05 Datasheet - Page 35

• Manufacturer Part Number: NCP5331_05
• Description: Two-Phase PWM Controller with Integrated Gate Drivers
• Manufacturer: ONSEMI [ON Semiconductor]

the 5.0 V reference output as shown in Figure 42. If the
resistor from I
then the resistor from I
from
10. Overcurrent Timer
and substitute t
11. Soft Start Time
size at a duty−cycle of D = 1.225 V/12 V = 0.102.
V ILIM + (I OUT,LIM ) DI Lo 2) @ (R LMAX ) R PCB,MAX )
Set the voltage at the I
To set the overcurrent timer, solve Equation 35 for C
To set the Soft Start time, first calculate the external ramp
Ext_Ramp + D @
+ (72 A ) 7.20 A 2) @ (1.28 mW ) 0.26 mW)
+ 1.4 Vdc
R LIM1 + (V REF * V ILIM ) (V ILIM R LIM2 )
@ G ILIM
@ 12 V V
C OVC + t OVC (5.5
+ (5.0 V * 1.4 V) (1.4 V 910 W)
+ 2340 W or 2.37 kW
LIM
OVC
+ 0.102 @
+ 5.5 mV
to GND is chosen to be 910 W (R
+ 120 ms (5.5
+ 0.218 mF or 0.22 mF
= 120 ms.
(R Sx @ C Sx @ f SW )
LIM
LIM
(V IN * V OUT )
(10.0 kW @ 0.1 mF @ 200 kHz)
pin using a resistor divider from
to 5.0 V
(12 V * 1.225 V)
10 5 )
REF
10 5 )
can be calculated
http://onsemi.com
LIM2
OVC
(35)
NCP5331
),
35
C
12. Power Good Delay Time
calculate the current that will be supplied to the C
capacitor.
required.
C PGD + t PGD @ I PGD (PGD THRESH * PGD MIN )
C2
C C2 + (t SS @ I COMP ) (V COMP * R C1 @ I COMP )
I PGD + 0.52 V R OSC
Then calculate the steady−state COMP voltage.
Finally, solve Equation 35 for the soft−start capacitor,
First, use the previously derived value for R
Next, solve equation 37 for C
V COMP + V OUT @ 0 A ) Channel_Startup_Offset
, and substitute as required.
+ (6 ms @ 30 mA) (1.86 V * 7.5 kW @ 30 mA)
+ 0.11 mF or 0.1 mF
+ 6 ms @ 10.2 mA (3.0 V * 0.25 V)
+ 0.022 mF
+ 0.52 V 51 kW
+ 10.2 mA
Figure 42. Setting the Current Limit
5 V
+ 1.225 V ) 0.60 V ) 0.102 @ 250 mV
+ 1.86 V
REF
) Int_Ramp ) G CSA @ Ext_Ramp 2
) 4.0 V V @ 5.3 mV 2
R
LIM1
V
LIM
R
910
LIM2
To I
PGD
LIM
Pin
and substitute as
OSC
PGD
(36)
(37)
to