NCP1381 ONSEMI [ON Semiconductor], NCP1381 Datasheet - Page 20

• Manufacturer Part Number: NCP1381
• Description: Low−Standby High Performance PWM Controller
• Manufacturer: ONSEMI [ON Semiconductor]

Brown−out internal circuit
a hiccup mode when there is not enough mains detected on Pin 2. Figure 32 portrays the solution based on a 1mA current
source, solely activated when the V
discharges the V
the V
1 mA. The logic arrangement is made in such a way that if the mains comes back asynchronously to V
or in the upslope), we always restart at V
Figure 34 and 35 confirm the good restart synchronization with the 15 V level.
V1 Timing 0 PWL 0 0.2 3s 1 7s 1 10s 0.2
V2 Line 0 SIN 150 50
Given the low startup current and the weak overall consumption of the controller, a circuit needs to be found in order to create
CC
D
Line
capacitor. When we reach 15 V, the logic checks whether the BOK gives the green light. If not, V
+
V
V1
(line)
CC
Figure 30. A Simple Simulation Configuration Helps to Tailor the Right Value for C
Timing
V
capacitor to make V
(timing)
+
V2
−100
−200
200
100
+
0
B1
Voltage
16
12
Bulk
Figure 31. Typical Signals Obtained from the Simulator
8
4
0
R
R
CC
upper
lower
Turn−off Voltage Occurs at:
V
is going low and the BOK has not authorized the controller to pulse. This 1 mA actually
2
3
8.156
inRMS
CC
IN
CC
reach 10 V. At this point, the source goes to zero and the startup resistor replenishes
= 15 V. Figure 33 shows a simulated behavior with a mains going up and down.
= 72.3 V
C
220 n
8.175
fil
http://onsemi.com
NCP1381
+
−
+
P
EB
B
Voltage
V
8.195
brown
(CMP)
Spice
20
brown
5
+
−
V
:
C
47 mF
I
u 3 ? 250 m : 500 m
brown−out
C
bulk
Value + { IF (V (CMP) u 3, 250 m, 0) }
= 40
8.215
TiCMP
Bulk
V (CMP) u 3 ?
P
EB
Current
B
Spice
load
8.235
V
load
Brown Out
load
:
Value + IF (V (CMP) u 3,
V (bulk)
35
: 0
CC
(e.g. in the downslope
CC
fil
goes low via the
V(bulk)
35
, 0)