LNK520
5.5 V, 500 mA
1
7
L1
1 mH
0.15 A
R1
390 kΩ
1/4 W
D7
11DQ06
C6
330 µF
16 V
C4
330 pF
1 kV
D1
D2
8T
1N4005 1N4005
RTN
6
5
2
RF1
8.2 Ω
2 W
R2
100 Ω
100T
J1
L
D5
1N4007GP
C3
26T
85 - 265
VAC
1 µF
R3
15 Ω
C1
4.7 µF
400 V
C2
D6B
1N4937
50 V
4.7 µF
4
400 V
T1
N
LinkSwitch
EE16
U1
LP = 2.52 mH
D
S
LNK520P
D3
D4
C
1N4005 1N4005
R4
6.81 k
Ω
C5
220 nF
1%, 1/4 W
PI-3723-111303
Figure 10. 2.75 W Constant Voltage/Constant Current (CV/CC) Charger Using LinkSwitch.
10
9
85 VAC
115 VAC
190 VAC
230 VAC
265 VAC
Limits
8
7
6
5
4
3
2
1
0
0
100
200
300
Output Current (mA)
Figure 11. Measured Output Characteristic of the Circuit in Figure 10.
400
500
600
700
The secondary of the transformer is rectified and filtered by
D7 and C6 to provide the DC output to the load. LinkSwitch
dramatically simplifies the secondary side by controlling both
the constant voltage and constant current regions entirely from
the primary side. This is achieved by monitoring the primary-
side bias voltage.
Diode D5, C4, R1 and R2 form the primary clamp network.
This limits the peak DRAIN voltage due to leakage inductance.
Resistor R2 allows the use of a slow, low cost rectifier diode
by limiting the reverse current through D5 when U1 turns on.
The selection of a slow diode improves radiated EMI and also
improves CV regulation, especially at no-load.
E
2/05
7
POWERINT [ Power Integrations ]
