NCP1351 查看數據表（PDF） - ON Semiconductor
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NCP1351 Datasheet PDF : 19 Pages
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NCP1351
HV−Bulk
U1B
C12
R15
+ 100mF 3.7k
400V
C15
22p
C4
R5
100n 2.5k
U2
1
8
2
7
3
6
4
5
NCP1351B
C9 R1
100n 2.2k
R3
R4
47k
22
R13 C2
R7
47k 10n
1M
400V
R2
1M
D2
MUR
160
D3
1N4937
OVP
Option
D6
1N4148
25V
R16
10
LP = 500mH
NP:NS = 1:0.25
NP:Naux = 0.18
D5
MBR20200
C5b
1.2mF
25V
C5a +
+
1.2mF
25V
T1 C13
2.2nF
Type = Y1
6A/600V
M1
U1A
C10 +
0.1m
R18
+
47k
C17
100m
L2
2.2m
C7 +
220mF
25V
GND
R8
1k
R14 C6
2.2k 100n
IC2
TL431
VOUT 19V/3A
R12
4k
R10
62k
R9
10k
R6
C8
0.4
270pF
C3 C1
4.7m 100nF
GND
25V
Figure 21. The 19 V Adapter Featuring the Elements Calculated Above
On this circuit, the VCC capacitor is split in two parts, a
low value capacitor (4.7 mF) and a bigger one (100 mF). The
4.7 mF capacitor ensures a low startup time, whereas the
second capacitor keeps the VCC alive in standby mode
(where the switching frequency can be low). Due to D6, it
does not hamper startup time.
Application Results
We assembled a board with component values close to
what is described on Figure 21. Here are the obtained
results:
Pin @ no−load = 152 mW, Vin = 230 Vac
Pin @ no−load = 164 mW, Vin = 100 Vac
The efficiency stays flat to above 80%, and keeps good
even at low output levels. It clearly shows the benefit of the
variable frequency implemented in the NCP1351.
Another benefit of the variable frequency lies in the low
ripple operation at no−load. This is what confirms
Figure 23.
Finally, the power supply was tested for its transient
response, from 100 mA to 3 A, high and low line, with a
slew−rate of 1 A/ms (Figure 25). Results appear in
Figures 25 and 26 and confirm the stability of the board.
88
86
Vin = 230 Vac
84
82
Vin = 100 Vac
80
78
76
74
72
0
0.5 1
1.5 2
2.5 3
3.5
Iout (A)
Figure 22. Efficiency Measured at Various Operating
Points
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