1) Initial condition setting can shorten simulation time and improve convergence by setting component voltages and currents at the start of simulation. 2) Simulating with the VCC startup voltage and initial conditions set on other nodes showed differences in simulation time. 3) Setting the output voltage initial condition below 19V instead of simulating the VCC startup also reduced simulation time. 4) Setting initial conditions on all nodes led to the fastest simulation time of 20.3 minutes for the full circuit simulation.

1. Initial condition setting for application
circuit simulation
1) Purpose of initial condition setting
2) VCC startup voltage vs. initial condition (.IC) setting
3) Output voltage (19V) startup vs. initial condition (.IC) setting
4) Simulation result with all initial condition (IC) is set
5) Simulation circuit with all initial condition (IC) is set
1

2. 1) Purpose of initial condition setting
• Shorten simulation time
• Improve simulation convergence
2

3. 2) VCC startup voltage vs. initial condition (.IC) setting
V(C1)
IC=139
V(VH)
Setup IC to shorten simulation time 50.537ms
V(VCC)
IC=10.19
(Value less than
VCCON)
V(OUT) IC_ON
IC_OFF
3

4. 2) VCC startup voltage vs. initial condition (.IC) setting
K K1
K_Linear C6
COUPLING = 0.98
L1 = Ls
4700pF
L2 = Lp
L3 = Lsub
C_T1 DY G865C15R
D21
2200pF
D22
Rp_T1 L1
0.001 4.7uH RSL1
1 2 VO_19V
D23
D1 1m
R2 C3 2 1
56k 2200pF D24 3300uFx3
Lp Ls C4 C5 RL
IC=139 {Lp} {Nsp*Nsp*Lp} 9900uF 1000uF 3.8
D3 ESR=20m/3 IC = 0
V1 C1 DERA38-06 ESR5
VOFF = 0 220uF 1 2 ESR4 20m
VAMPL = 141.42 D3SBA60/SDG IC = 0 6.7m
FREQ = 50
U1 R7 0
2SK3681-01S 2k
Cd PARAMETERS: R15
100V/50Hz 220pF Np = 57 200k
FB
R6
Ns = 10 10k
D2 R8 Nsub = 6
DERA15-01 10 4.7k C8 R3
R10 Lp = 360uH
2200pF 18k
Nsp = {Ns/Np} U14
R1 Rsns Nsubp = {Nsub/Np}
0 TLP281
7.5k 100 C9
0.22
R11 R5 2200pF
R14
100 D4
10k
R13 DSC902-2 U12
100k IS LMV431
R4
U15 15k
FA5541 R12 DERA22-02
ZCD 4.7 D5
ZCD VH
1
Lsub
FB NC {Nsubp*Nsubp*Lp}
C7
IS VCC
22pF FB
GND OUT
SSIC = 0 2
C12 C11 C2
1000pF 4700pF 33uF
IC = 0
0
IC=10.19
(Value less than
VCCON)
4

5. 3) Output voltage (19V) startup vs. initial condition (.IC) set
(VCC startup is skipped)
IC=4.2
V(FB)
V(IS)
TSFT = 1ms
IC=18
(Value less than
19V) 19V
Vout DC 19V
Setup IC to shorten simulation time 38ms
(Total job time ≈ 30minute)
Total job time ≈ 50min.
5

6. 3) Output voltage (19V) startup vs. initial condition (.IC) set
(VCC startup is skipped)
K K1
K_Linear C6
COUPLING = 0.98
L1 = Ls
4700pF
L2 = Lp
L3 = Lsub
C_T1 DY G865C15R
D21
2200pF
D22
Rp_T1 L1
0.001 4.7uH RSL1
1 2 VO_19V
D23
D1 1m
R2 C3 2 1
56k 2200pF D24 3300uFx3
Lp Ls C4 C5 RL
{Lp} {Nsp*Nsp*Lp} 9900uF 1000uF 3.8
D3 ESR=20m/3 IC = 0
V1 C1 DERA38-06 ESR5
VOFF = 0 220uF 1 2 ESR4 20m
VAMPL = 141.42 D3SBA60/SDG IC = 139 6.7m IC=18
FREQ = 50
(Value less than
U1 R7 0
2SK3681-01S
19V)
2k
Cd PARAMETERS: R15
100V/50Hz 220pF Np = 57 200k
FB
R6
Ns = 10 10k
D2 R8 Nsub = 6
DERA15-01 10 4.7k C8 R3
R10 Lp = 360uH
2200pF 18k
Nsp = {Ns/Np} U14
R1 Rsns Nsubp = {Nsub/Np}
0 TLP281
7.5k 100 C9
0.22
R11 R5 2200pF
R14
100 D4
10k
R13 DSC902-2 U12
100k IS LMV431
R4
U15 15k
FA5541 R12 DERA22-02
ZCD 4.7 D5
ZCD VH
1
Lsub
FB NC {Nsubp*Nsubp*Lp}
C7
IS VCC
22pF FB
GND OUT
SSIC = 0 2
C12 C11 C2
1000pF 4700pF 33uF
IC = 0 SSIC=1 IC = 10.19
to skip
TSFT 0
IC=4.2
 Soft start function is canceled by set SSIC=1
6

7. 4) Simulation result with all initial condition (IC) is set
V(VCC)
VCC=VSTOFF = 12.4V
V(C1)
V(VH)
V(FB)
V(IS)
Vout DC 19V 19V
Total job time = 20.3min.
7

8. 5) Simulation circuit with all initial condition (IC) is set
K K1
K_Linear C6
COUPLING = 0.98
L1 = Ls
4700pF
L2 = Lp
L3 = Lsub
C_T1 DY G865C15R
D21
2200pF
D22
Rp_T1 L1
0.001 4.7uH RSL1
1 2 VO_19V
D23
D1 1m
R2 C3 2 1
56k 2200pF D24 3300uFx3
Lp Ls C4 C5 RL
IC=139 {Lp} {Nsp*Nsp*Lp} 9900uF 1000uF 3.8
D3 ESR=20m/3 IC = 18
V1 C1 DERA38-06 ESR5
VOFF = 0 220uF 1 2 ESR4 IC=0/18 20m
VAMPL = 141.42 D3SBA60/SDG IC = 139 6.7m IC=18
FREQ = 50 IC=0/139
(Value less than
U1 R7 0
2SK3681-01S
19V)
2k
Cd PARAMETERS: R15
100V/50Hz 220pF Np = 57 200k
FB
R6
Ns = 10 10k
D2 R8 Nsub = 6
DERA15-01 10 4.7k C8 R3
R10 Lp = 360uH
2200pF 18k
Nsp = {Ns/Np} U14
R1 Rsns Nsubp = {Nsub/Np}
0 TLP281
7.5k 100 C9
0.22
R11 R5 2200pF
R14
100 D4
10k
R13 DSC902-2 U12
100k IS LMV431
R4
U15 15k
FA5541 R12 DERA22-02
ZCD 4.7 D5
ZCD VH
1
Lsub
FB NC {Nsubp*Nsubp*Lp}
C7
IS VCC
22pF FB
GND OUT
SSIC = 1 2
C12 C11 IC=0/1 C2
1000pF 4700pF 33uF
IC = 4.2 SSIC=1 IC = 10.19
IC=0/4.2
to skip IC=0/10.19
TSFT 0
IC=10.19
IC=4.2 (Value less than
VCCON)
8