ncp1927 ON Semiconductor, ncp1927 Datasheet - Page 11

• Manufacturer Part Number: ncp1927
• Description: Combination Power Factor Correction Controller And Flyback Controller For Flat Panel Tvs
• Manufacturer: ON Semiconductor

FAULT MANAGEMENT
(Shutdown Mode, TSD, and Flyback Overload), the drivers
are disabled, and V
internal current consumption. Once V
V
consumption is reduced to the startup current, I
begins to rise as if power was initially applied and the device
resumes normal operation once V
cycle between V
as a V
I
CC(off)
CC1
When the NCP1927 detects a non−latching fault
+I
Figure 3. Operation with Dual V
CC(FDRV)
Figure 4. Startup Sequence of the NCP1927
CC
, the fault is reset and the IC internal current
I
CC3
hiccup and is shown in Figure 5.
PDRV
FDRV
+I
+
V
ICC(FDRV)
CC(PDRV)
I CC
V
CC(reset)
V
CC(on)
PDRV
FDRV
CC(off)
V
DRV
I
CC(on)
CC
CC5
0 V
I
CC
CC
V CC
and V
falls towards V
+
V in
NCP1927
R start
C1
D1
CC(off)
+
CC
C2
is commonly referred to
D2
reaches V
CC(off)
CC
Capacitors
CC
Aux Winding
due to the IC
falls below
CC(on)
CC5
http://onsemi.com
. V
Time
. This
Time
Time
CC
11
SHUTDOWN PIN
NCP1927. When V
threshold, V
PFC drive outputs are immediately turned off, and a V
hiccup occurs (see Figure 5). When V
the cycle repeats unless the NCP1927 is taken out of
shutdown. This is achieved when V
than V
start when V
power−on sequence. The V
mode is shown in Figure 6.
The Shutdown pin allows for external disabling of the
V
V
I
I
I
CC
CC
CC
CC
CC
DRV
V
OFF
4
ON
I
2
5
CC
SHDN
CC
Figure 5. V
. The NCP1927 leaves shutdown mode and will
SHDN
Occurs
CC
Fault
reaches V
(typically 1.0 V), both the flyback and
Shutdown
CC
Fault is Reset
During a V
CC(on)
CC
is pulled above the shutdown
Restarts
behavior during shutdown
Device
according to the initial
Shutdown
CC
CC
Hiccup
reaches V
becomes less
CC(on)
time
time
time
CC
,