* SPICE netlist
R1 N015 0 105K
R2 IN N009 1K
R3 IN N010 115K
R4 N010 0 15K
V1 IN 0 12
C1 N014 0 1
MQ1 N003 N005 N007 N007 Si7370DP
R5 N007 0 10m
L1 N003 IN 20 Rser=50m
L2 0 N001 200 Rser=.2 Rpar=5K
D1 N001 N002 1N5817
D2 0 N002 1N5817
C2 OUT 0 20
L3 N002 OUT 25 Rpar=2.5K
C3 N016 0 .001
C4 N012 0 470p
C5 N008 N011 .002 Rser=1K
C6 OUT N013 .01 Rpar=1K
R6 N008 0 2.49K
C7 OUT N008 .001 Rser=1K Rpar=21.5K
XU1 N010 N016 N009 N012 N015 0 N005 N014 0 N006 0 LTC3725 ;pnba UVLO)SSFLT)Ndrv)FB/IN+)FS/IN-)PGND)Gate)Vcc)VSLMT)IS)GND
D3 N004 N014 MMSD4148
D4 IN N004 MMSD4148
R7 N007 N006 100
C8 N006 0 500p
R8 OUT N017 4.8K
Rload OUT 0 50
XU2 N013 N011 N012 0 NC_01 MOC205 Igain=2.44m ;pnba A)K)C)E)B
XU3 N011 NC_02 N017 NC_03 0 0 NC_04 N008 LT1431 ;pnba Coll)Comp)V+)Rtop)GND-S)GND-F)Rmid)Ref
K1 L1 L2 1
.tran 1m startup

* LTspice schematic (.asc)
Version 4
SHEET 1 1648 720
WIRE -712 -360 -808 -360
WIRE -520 -360 -712 -360
WIRE -344 -360 -520 -360
WIRE -104 -360 -344 -360
WIRE 56 -360 40 -360
WIRE 152 -360 120 -360
WIRE 184 -360 152 -360
WIRE 296 -360 264 -360
WIRE 360 -360 296 -360
WIRE 424 -360 360 -360
WIRE -344 -344 -344 -360
WIRE -104 -344 -104 -360
WIRE -56 -344 -104 -344
WIRE 40 -344 40 -360
WIRE 40 -344 -8 -344
WIRE -712 -328 -712 -360
WIRE -56 -328 -56 -344
WIRE -8 -328 -8 -344
WIRE 296 -328 296 -360
WIRE 424 -328 424 -360
WIRE 152 -312 152 -360
WIRE -344 -248 -344 -264
WIRE -56 -232 -56 -248
WIRE -56 -232 -104 -232
WIRE -8 -232 -8 -248
WIRE 40 -232 -8 -232
WIRE -520 -216 -520 -360
WIRE 40 -216 40 -232
WIRE 152 -216 152 -248
WIRE 152 -216 40 -216
WIRE 296 -216 296 -264
WIRE 296 -216 152 -216
WIRE 424 -216 424 -248
WIRE 424 -216 296 -216
WIRE 424 -200 424 -216
WIRE -712 -168 -712 -264
WIRE -152 -152 -376 -152
WIRE -312 -88 -328 -88
WIRE -232 -88 -248 -88
WIRE -200 -88 -232 -88
WIRE -104 -88 -104 -136
WIRE -104 -88 -120 -88
WIRE -808 -72 -808 -360
WIRE -104 -72 -104 -88
WIRE 360 -56 360 -360
WIRE 424 -56 360 -56
WIRE 712 -56 488 -56
WIRE 728 -56 712 -56
WIRE 824 -56 808 -56
WIRE -520 -40 -520 -136
WIRE -376 -40 -376 -152
WIRE -232 -40 -232 -88
WIRE -104 24 -104 8
WIRE -808 40 -808 8
WIRE -632 40 -808 40
WIRE -808 56 -808 40
WIRE 536 56 408 56
WIRE 712 56 712 -56
WIRE 712 56 600 56
WIRE -88 72 -136 72
WIRE 8 72 -88 72
WIRE 248 72 200 72
WIRE 360 72 360 -56
WIRE 360 72 312 72
WIRE -88 88 -88 72
WIRE 8 136 -8 136
WIRE -808 152 -808 136
WIRE -712 152 -712 -104
WIRE -632 152 -712 152
WIRE -88 168 -88 152
WIRE 408 168 408 56
WIRE 408 168 200 168
WIRE 440 168 408 168
WIRE 712 168 712 56
WIRE 712 168 696 168
WIRE 360 200 360 72
WIRE -712 232 -712 216
WIRE -88 232 -136 232
WIRE -88 248 -88 232
WIRE -632 264 -712 264
WIRE -712 280 -712 264
WIRE 360 296 360 280
WIRE 440 296 360 296
WIRE 712 296 696 296
WIRE -88 344 -88 328
WIRE -520 360 -520 344
WIRE -376 360 -376 344
WIRE -232 360 -232 344
WIRE 712 360 696 360
FLAG -232 360 0
FLAG -376 360 0
FLAG -88 344 0
FLAG -808 152 0
FLAG -344 -248 0
FLAG -712 232 0
FLAG -104 24 0
FLAG 424 -200 0
FLAG -88 168 0
FLAG -712 344 0
FLAG -8 136 0
FLAG 712 360 0
FLAG 712 296 0
FLAG 824 -56 0
FLAG 424 -360 OUT
FLAG -520 360 0
FLAG -328 -88 0
FLAG -344 -360 IN
SYMBOL res -104 232 R0
SYMATTR InstName R1
SYMATTR Value 105K
SYMBOL res -536 -232 R0
SYMATTR InstName R2
SYMATTR Value 1K
SYMBOL res -824 -88 R0
SYMATTR InstName R3
SYMATTR Value 115K
SYMBOL res -824 40 R0
SYMATTR Value 15K
SYMATTR InstName R4
SYMBOL voltage -344 -360 R0
SYMATTR InstName V1
SYMATTR Value 12
SYMBOL cap -728 152 R0
SYMATTR InstName C1
SYMATTR Value 1
SYMBOL nmos -152 -232 R0
SYMATTR InstName Q1
SYMATTR Value Si7370DP
SYMBOL res -120 -88 R0
SYMATTR InstName R5
SYMATTR Value 10m
SYMBOL ind2 -72 -232 M180
SYMATTR InstName L1
SYMATTR Value 20
SYMATTR Type ind
SYMATTR SpiceLine Rser=50m
SYMBOL ind2 8 -232 R180
SYMATTR InstName L2
SYMATTR Value 200
SYMATTR Type ind
SYMATTR SpiceLine Rser=.2 Rpar=5K
SYMBOL schottky 56 -344 R270
SYMATTR InstName D1
SYMATTR Value 1N5817
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL schottky 136 -248 M180
SYMATTR InstName D2
SYMATTR Value 1N5817
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL cap 280 -328 R0
SYMATTR Value 20
SYMATTR InstName C2
SYMBOL ind 168 -344 R270
SYMATTR InstName L3
SYMATTR Value 25
SYMATTR SpiceLine Rpar=2.5K
SYMBOL cap -728 280 R0
SYMATTR InstName C3
SYMATTR Value .001
SYMBOL cap -104 88 R0
SYMATTR InstName C4
SYMATTR Value 470p
SYMBOL cap 600 40 R90
SYMATTR InstName C5
SYMATTR Value .002
SYMATTR Value2 Rser=1K
SYMBOL cap 312 56 R90
SYMATTR InstName C6
SYMATTR Value .01
SYMATTR SpiceLine Rpar=1K
SYMBOL res 712 -40 R270
SYMATTR InstName R6
SYMATTR Value 2.49K
SYMBOL cap 424 -40 R270
SYMATTR Value2 Rser=1K
SYMATTR InstName C7
SYMATTR Value .001
SYMATTR SpiceLine Rpar=21.5K
SYMBOL PowerProducts\\LTC3725 -376 152 R0
SYMATTR InstName U1
SYMBOL diode -728 -168 R0
SYMATTR InstName D3
SYMATTR Value MMSD4148
SYMBOL diode -728 -328 R0
SYMATTR InstName D4
SYMATTR Value MMSD4148
SYMBOL res -104 -104 R90
SYMATTR InstName R7
SYMATTR Value 100
SYMBOL cap -248 -104 R90
SYMATTR InstName C8
SYMATTR Value 500p
SYMBOL res 344 184 R0
SYMATTR InstName R8
SYMATTR Value 4.8K
SYMBOL res 408 -344 R0
SYMATTR InstName Rload
SYMATTR Value 50
SYMBOL optos\\MOC207 104 136 M0
SYMATTR InstName U2
SYMBOL LT1431 568 264 R0
SYMATTR InstName U3