1. Bee Technologies
http://www.bee-tech.info/
Design Kit
Flyback Converter using PWM IC
LTspice Version
1Copyright (C) Siam Bee Technologies 2015
02JUL2015

2. Contents
1. 50W Off-Line Adapter Circuit (VIN=85Vac)
1.1) Input Waveform
1.2) Output Waveform
1.3) Output Power
1.4) Gate Drive Output and Oscillator Timing (IC)
2. 50W Off-Line Adapter Circuit (VIN=110Vac)
2.1) Input Waveform
2.2) Output Waveform
2.3) Output Power
2.4) Gate Drive Output and Oscillator Timing (IC)
3. 50W Off-Line Adapter Circuit (VIN=265Vac)
3.1) Input Waveform
3.2) Output Waveform
3.3) Output Power
3.4) Gate Drive Output and Oscillator Timing (IC)
4. Transformer Specification
5. Operation Waveform (VIN=110Vac, Example)
5.1) Transformer Turn Ratio
5.2) Transformer Primary Side Inductance (LP)
5.3) VCC Output Waveform
5.4) MOSFET Switching Device (UQ101)
5.5) Output Rectifier Diode (D201 - D202)
5.6) Current Sensing and Feedback Circuit
Conclusion
Simulation Details
Appendix A - Initial Condition Settings
Appendix B - Bill of Materials
Simulation Index
2Copyright (C) Siam Bee Technologies 2015

3. 1. 50W Off-Line Adapter Circuit (VIN=85Vac)
- Simulation Circuit
3Copyright (C) Siam Bee Technologies 2015
.tran 0 50m 0 10n
.Option Gmin=75E-9
.Option Abstol=1.0E-9
.Option Vntol=1.0u
.Option Trtol=1000
.Option Method=Gear
* Engine Solver: Alternate
 Initial condition are set ,so the simulation starts near the steady state.
VIN=85Vac
V(Out) starts from 11V
by the initial condition
V(Vcc) starts from 12V

4. 1.1) Input Waveform
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 4
Time [sec]
VDC,AVG = 104.33V
VAC = 85Vrms
VDC, MIN = 85.8V

5. 1.2) Output Waveform
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 5
The output voltage is regulated at 12.12V
Time [sec]
The output current is 4.04A (RL=3)
V(Out) starts from 11V
by the initial condition

6. 1.3) Output Power
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 6
Time [sec]
The simulation result shows the output power is 48.90W

7. 1.4) Gate Drive Output and Oscillator Timing (IC)
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 7
Time [sec]
VOSC
Oscillator frequency = 105kHz
PW = 3.877us

8. 2. 50W Off-Line Adapter Circuit (VIN=110Vac)
- Simulation Circuit
8Copyright (C) Siam Bee Technologies 2015
.tran 0 50m 0 10n
.Option Gmin=75E-9
.Option Abstol=1.0E-9
.Option Vntol=1.0u
.Option Trtol=1000
.Option Method=Gear
* Engine Solver: Alternate
 Initial condition are set ,so the simulation starts near the steady state.
VIN=110Vac
V(Vcc) starts from 12V
V(Out) starts from 11V
by the initial condition

9. 2.1) Input Waveform
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 9
Time [sec]
VDC,AVG = 142.41V
VAC = 110Vrms
VDC, MIN = 128.621V

10. 2.2) Output Waveform
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 10
The output voltage is regulated at 12.118V
Time [sec]
The output current is 4.039A (RL=3)
V(Out) starts from 11V
by the initial condition

11. 2.3) Output Power
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 11
Time [sec]
The simulation result shows the output power is 48.95W

12. 2.4) Gate Drive Output and Oscillator Timing (IC)
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 12
Time [sec]
PW = 3.282us
VOSC
Oscillator frequency = 105kHz

13. 3. 50W Off-Line Adapter Circuit (VIN=265Vac)
- Simulation Circuit
13Copyright (C) Siam Bee Technologies 2015
.tran 0 50m 0 10n
.Option Gmin=75E-9
.Option Abstol=1.0E-9
.Option Vntol=1.0u
.Option Trtol=1000
.Option Method=Gear
* Engine Solver: Alternate
 Initial condition are set ,so the simulation starts near the steady state.
VIN=265Vac
V(Vcc) starts from 12V
V(Out) starts from 11V
by the initial condition

14. 3.1) Input Waveform
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 14
Time [sec]
VDC,AVG = 367.58V
VAC = 265Vrms
VDC, MIN = 361.264V

15. 3.2) Output Waveform
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 15
The output voltage is regulated at 12.075V
Time [sec]
The output current is 4.025A (RL=3)
V(Out) starts from 11V
by the initial condition

16. 3.3) Output Power
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 16
Time [sec]
The simulation result shows the output power is 48.70W

17. 3.4) Gate Drive Output and Oscillator Timing (IC)
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 17
Time [sec]
PW = 1.706us
VOSC
Oscillator frequency = 105kHz

18. 4. Transformer Specification
Copyright (C) Siam Bee Technologies 2015 18
NP NS
NSUB
Pin (S--F) Turns
NP 1 → 3 54
NS 9 → 12 10
NSUB 5 → 6 10
Winding Specification
Pin Value
Inductance 1 - 3 600uH
Leakage 1 - 3 15uH
Electrical Specification
 To model the transformer (or coupled inductors), we can use the SPICE primitive k,
which describes the coupling ratio between a primary and a secondary.

19. 5. Operation Waveform (VIN=110Vac, Example)
- Simulation Circuit
19Copyright (C) Siam Bee Technologies 2015
+
VDS
-
ID
- +
VKA
IF
The system parameter are as follows:
- Maximum output power : 50W
- Input voltage : 110Vrms
- AC line frequency : 50Hz
- Switching frequency : 100kHz
VIN=110Vac
+
VCC
-
V(Out) starts from 11V
V(Vcc) starts from 12V

20. 5.1) Transformer Turn Ratio
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 20
Time [sec]
VP
VS
VCC
 This figure shows the waveforms of the voltages at each side of the transformer.

21.  This figure shows the waveforms of ID(UQ101) and IF(D201, D202) in the CCM mode.
 The primary-side inductance (LP) of the transformer determines the converter operation mode.
5.2) Transformer Primary Side Inductance (LP)
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 21
Time [sec]
ΟNΤ
Τ
IF(D201, D202)
VPWM
ID(UQ101)

22. 5.3) VCC Output Waveform
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 22
Time [sec]
VCC = 12.367V

23. 5.4) MOSFET Switching Device (UQ101)
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 23
Time [sec]
VDS(t)
ID(t)
Switching
loss (turn-off)
Switching loss
(turn-on)
Conduction loss
(VDS x ID)

24. 5.5) Output Rectifier Diode (D201 - D202)
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 24
Time [sec]
VKA(t) IF(t)
Peak magnitude
current
Conduction loss
(VF,AK x IF)
PLOSS_(D201, 202) (t)

25. 5.6) Current Sensing and Feedback Circuit
- Simulation Result
Copyright (C) Siam Bee Technologies 2015 25
Time [sec]
1V Comparator
VCS

26. Conclusion
Copyright (C) Siam Bee Technologies 2015 26
Input voltage Output power Oscillator frequency PW
85Vac 48.95 W 105 kHz 3.877 us
110Vac 48.95 W 105 kHz 3.278 us
265Vac 48.70 W 105 kHz 1.706 us
Simulation Results

27. Simulation Details
Analysis directives:
.Tran 0 50m 0 10n
.Option Gmin=75E-9
.Option Abstol=1.0E-9
.Option Vntol=1.0u
.Option Trtol=1000
.Option Method=Gear
* Engine Solver: Alternate
Libraries:
.LIB 2sk4101ls.lib
.LIB an1431t.lib
.LIB pc817c.lib
.LIB d2sba60.lib
.LIB mbrf20100ct.lib
.LIB era91-02.lib
.LIB 1n5408.lib
.LIB fan7601.lib
27Copyright (C) Siam Bee Technologies 2015

28. Appendix A
- Initial Condition Settings
Copyright (C) Siam Bee Technologies 2015 28
Initial phase= 90
.IC V(Vdc_in)= {Vac*√2}
.IC V(Vcc)= 12V
.IC V(Out) = 11V
.IC V(Cs)= 0V
.IC V(Rt_Ct)= 0V
.IC V(Ls)= 2V

29. Appendix B
- Bill of Materials
Copyright (C) Siam Bee Technologies 2015 29
Designator Manufacturer Part Number Comment Designator Manufacturer Part Number Comment
R1 - 10Ω - C109 - 0.47uF -
R103 - 56kΩ - C112 - 0.1uF -
R105 - 100Ω - C201 - 1000uF -
R107 - 0.5Ω - C202 - 1000uF -
R108 - 1kΩ - C203 - 1nF -
R109 - 8kΩ - C222 - 2.2nF -
R110 - 3.9kΩ - D1 Fairchild 1N5408 Spice model
R201 - 3.3kΩ - D101 Fairchild 1N5408 Spice model
R202 - 1.2kΩ - D102 Fairchild 1N5408 Spice model
R204 - 27kΩ - D103 Fuji Electric ERA91-02 Spice model
R205 - 7kΩ - D201 ON Semi. MBRF20100CT Spice model
R206 - 10Ω - D202 ON Semi. MBRF20100CT Spice model
C1 - 1nF - U1 Shindengen D2SBA60 Spice model
C103 - 150uF - U101 Fairchild FAN7601 Spice model
C105 - 10pF - UQ101 Sanyo 2SK4101LS Spice model
C106 - 2.7nF - U201 Panasonic AN1431T Spice model
C107 - 47uF - U301 Sharp PC817C Spice model
C108 - 0.01uF -

30. Simulation Index
30
Simulations Folder name
1. 50W Off-Line Adapter Circuit (VIN=85Vac)................
2. 50W Off-Line Adapter Circuit (VIN=110Vac)..............
3. 50W Off-Line Adapter Circuit (VIN=85Vac)................
4. Operation Waveform (VIN=110Vac, Example)...........
../Simulation data/VIN_85VAC
../Simulation data/VIN_110VAC
../Simulation data/VIN_265VAC
../Simulation data/Operation Waveform
Copyright (C) Siam Bee Technologies 2015