ncp1608 ON Semiconductor, ncp1608 Datasheet - Page 18

• Manufacturer Part Number: ncp1608
• Description: Critical Conduction Mode Pfc Controller Utilizing A Transconductance Error Amplifier
• Manufacturer: ON Semiconductor

Soft Start
t
charging the compensation network. The drive is enabled
when V
compensation network slowly increases the drive on time
from the minimum time (t
This creates a natural soft start mode that reduces the stress
of the power components (Figure 41).
Output Driver
of sourcing 500 mA and sinking 800 mA. This enables the
controller to drive power MOSFETs efficiently for medium
power (≤ 350 W) applications. Additionally, the driver
stage provides both passive and active pull−down circuits
(Figure 42). The pull−down circuits force the driver output
to a voltage less than the turn−on threshold voltage of a
power MOSFET when V
start
When V
The NCP1608 includes a powerful output driver capable
expires, the error amplifier is enabled and begins
Control
1
2
3
4
CC
NCP1608
exceeds V
exceeds Ct
Figure 40. NCP1608 Supplied by a Downstream SMPS Controller (NCP1230)
8
7
6
5
CC(on)
+
CC(on)
PWM
+
−
(offset)
+
PFC(Vcc)
, t
) to the steady state on time.
start
UVLO
is not reached.
Figure 42. Output Driver Stage and Pull−Down Circuits
. The charging of the
begins counting. When
1
2
3
4
NCP1230
V
DD REG
D
8
7
6
5
http://onsemi.com
V
V
V
CC
ddGD
DD
+
+
18
V
DRV IN
CC
C
UVLO
bulk
Ct
mV
Control
I
(offset)
Figure 41. Startup Timing Diagram Showing the
switch
V
DD
V
V
REF
FB
CC
out
Natural Soft Start of the Control Pin
+
t
start
Natural Soft Start
V
V
+
CC(on)
CC(off)
DRV
GND
+
−