LNK603-606/613-616
An overshoot
is acceptable
Negative ring may
increase output
ripple and/or
degrade output
regulation
Figure 6. Desired Drain Voltage Waveform with Minimal Leakage
Ringing Undershoot.
Figure 7.
Undesirable Drain Voltage Waveform with Large Leakage
Ring Undershoot.
L1
1 mH
TI
EE13
5
10
8
D7
SL13
C3
R2
470 kΩ
820 pF
3
1 kV
D1
D2
C7
470 µF
10 V
1N4007 1N4007
DC
Output
1 kΩ
R3
300 Ω
RF1
8.2 Ω
2 W
2
4
C1
4.7 µF
400 V
C2
4.7 µF
400 V
AC
Input
D5
1N4007
NC
LinkSwitch-II
R5
U1
13 kΩ
LNK613DG
1%
D
D3
D4
FB
1N4007 1N4007
BP
S
R6
9.31 kΩ
1%
C4
1 µF
50 V
PI-5116-050808
Figure 8. LinkSwitch-II Flyback Power Supply Without Bias Supply.
former saturation and excessive leading edge current spikes.
LinkSwitch-II has a leading edge blanking time of 170 ns to
prevent premature termination of the ON-cycle.
BYPASS pin voltage. The parameters IS2 and VBP are provided in
the parameter table of the LinkSwitch-II data sheet. Diode D6 can
be any low cost diode such as FR102, 1N4148 or BAV19/20/21.
3. Thermal check – At maximum output power, both minimum
and maximum input voltage and maximum ambient tempera-
ture; verify that temperature specifications are not exceeded
for LinkSwitch-II, transformer, output diodes and output
capacitors. Enough thermal margin should be allowed for
part-to-part variation of the RDS(ON) of LinkSwitch-II, as specified
in the data sheet. To assure 10% CC tolerance a maximum
SOURCE pin temperature of 90 ºC is recommended.
Quick Design Checklist
As with any power supply design, all LinkSwitch-II designs
should be verified on the bench to make sure that component
specifications are not exceeded under worst-case conditions.
The following minimum set of tests is strongly recommended:
1. Maximum drain voltage – Verify that peak VDS does not exceed
680 V at the highest input voltage and maximum output power.
2. Maximum drain current – At maximum ambient temperature,
maximum input voltage and maximum output load, verify
drain current waveforms at start-up for any signs of trans-
Design Tools
Up-to-date information on design tools can be found at the
Power Integrations web site: www.powerint.com
7
www.powerint.com
Rev. F 01/10
POWERINT [ Power Integrations ]
