* SPICE netlist
R1 N017 0 .67
C1 N018 0 220p
C2 N015 0 .1
C3 N014 N013 .01
R2 N013 N010 200K
R3 N015 N018 12K
R4 N010 0 20K
R5 N017 N016 1K
MQ1 N005 N012 N017 N017 BSC42DN25NS3
R6 N012 N011 10
R7 N006 N010 125K
C4 N006 0 .0022
C5 N007 0 100p
D1 N007 N006 BAT54
C6 N004 0 22
R8 N009 N004 39
D2 N008 N009 BAT54
R9 IN N016 1.32Meg
R10 IN N003 660K
C7 IN N003 470p
L1 N001 0 20 Rser=.05
L2 N008 0 16 Rser=.1
L3 N005 IN 100 Rser=.05
D3 N001 N002 MBRS340
L4 N002 OUT 1
C8 OUT 0 3.3
R11 OUT 0 750
V1 IN 0 200
D4 0 N004 BZX84C15L
D5 N005 N003 MURS320
R12 N008 N007 510
R13 IN N004 400K
XU1 N014 N010 N016 N018 0 N011 N004 N015 LT1243 ;pnba COMP)FB)Isense)Rt/Ct)GND)Output)Vcc)Vref
C9 N016 0 25p
I1 0 N004 pwl(0 0 50u 7 100u 0)
C10 N002 0 10 Rser=.1
Rload OUT 0 25
.tran 1m startup
K1 L1 L2 L3 1

* LTspice schematic (.asc)
Version 4
SHEET 1 1936 864
WIRE -424 -432 -712 -432
WIRE -232 -432 -424 -432
WIRE -56 -432 -232 -432
WIRE 56 -432 -56 -432
WIRE 200 -432 56 -432
WIRE -712 -416 -712 -432
WIRE -424 -400 -424 -432
WIRE -56 -400 -56 -432
WIRE 56 -400 56 -432
WIRE -232 -368 -232 -432
WIRE 200 -352 200 -432
WIRE 248 -352 200 -352
WIRE 408 -352 312 -352
WIRE 520 -352 472 -352
WIRE 568 -352 520 -352
WIRE 696 -352 648 -352
WIRE 824 -352 696 -352
WIRE 968 -352 824 -352
WIRE 248 -336 248 -352
WIRE 312 -336 312 -352
WIRE 520 -336 520 -352
WIRE 696 -336 696 -352
WIRE 824 -336 824 -352
WIRE 968 -336 968 -352
WIRE -712 -320 -712 -336
WIRE -56 -304 -56 -336
WIRE 56 -304 56 -320
WIRE 56 -304 -56 -304
WIRE 56 -288 56 -304
WIRE -616 -240 -680 -240
WIRE -424 -240 -424 -320
WIRE -424 -240 -536 -240
WIRE -376 -240 -424 -240
WIRE -280 -240 -312 -240
WIRE 248 -240 248 -256
WIRE 248 -240 200 -240
WIRE 312 -240 312 -256
WIRE 520 -240 520 -272
WIRE 520 -240 312 -240
WIRE 696 -240 696 -272
WIRE 696 -240 520 -240
WIRE 824 -240 824 -256
WIRE 824 -240 696 -240
WIRE 968 -240 968 -256
WIRE 968 -240 824 -240
WIRE 968 -208 968 -240
WIRE 56 -192 56 -224
WIRE 200 -192 200 -240
WIRE 200 -192 56 -192
WIRE -856 -112 -952 -112
WIRE -760 -112 -856 -112
WIRE -632 -112 -696 -112
WIRE -552 -112 -632 -112
WIRE 24 -112 -472 -112
WIRE 248 -112 24 -112
WIRE -856 -96 -856 -112
WIRE -632 -96 -632 -112
WIRE 248 -96 248 -112
WIRE -424 -48 -424 -240
WIRE -200 -48 -424 -48
WIRE -152 -48 -200 -48
WIRE -56 -48 -72 -48
WIRE 24 -48 24 -112
WIRE 24 -48 8 -48
WIRE -200 -32 -200 -48
WIRE -952 -16 -952 -112
WIRE -856 0 -856 -32
WIRE -632 0 -632 -32
WIRE 248 0 248 -16
WIRE -424 16 -424 -48
WIRE 56 32 56 -192
WIRE -200 48 -200 32
WIRE -952 80 -952 64
WIRE -584 80 -952 80
WIRE -136 112 -264 112
WIRE 8 112 -56 112
WIRE -952 144 -952 80
WIRE -824 144 -952 144
WIRE -696 144 -744 144
WIRE -584 144 -632 144
WIRE -952 160 -952 144
WIRE -728 208 -840 208
WIRE -584 208 -728 208
WIRE -840 224 -840 208
WIRE -728 224 -728 208
WIRE -232 240 -232 -288
WIRE -232 240 -264 240
WIRE -120 240 -232 240
WIRE 56 240 56 128
WIRE 56 240 -40 240
WIRE -952 256 -952 240
WIRE -232 256 -232 240
WIRE 56 256 56 240
WIRE -584 272 -632 272
WIRE -728 304 -728 288
WIRE -840 336 -840 304
WIRE -632 336 -632 272
WIRE -632 336 -840 336
WIRE -232 336 -232 320
WIRE -840 352 -840 336
WIRE 56 352 56 336
WIRE -424 384 -424 336
WIRE -840 432 -840 416
FLAG 56 352 0
FLAG -840 432 0
FLAG -728 304 0
FLAG -952 256 0
FLAG -424 384 0
FLAG -856 0 0
FLAG -632 0 0
FLAG -200 48 0
FLAG 248 0 0
FLAG -712 -320 0
FLAG -280 -240 0
FLAG 968 -352 OUT
FLAG 968 -208 0
FLAG -712 -432 IN
FLAG -232 336 0
FLAG -680 -240 0
SYMBOL RES 40 240 R0
SYMATTR InstName R1
SYMATTR Value .67
SYMBOL cap -856 352 R0
SYMATTR InstName C1
SYMATTR Value 220p
SYMBOL cap -744 224 R0
SYMATTR InstName C2
SYMATTR Value .1
SYMBOL cap -632 128 R90
SYMATTR InstName C3
SYMATTR Value .01
SYMBOL res -728 128 R90
SYMATTR InstName R2
SYMATTR Value 200K
SYMBOL res -856 208 R0
SYMATTR InstName R3
SYMATTR Value 12K
SYMBOL res -968 144 R0
SYMATTR InstName R4
SYMATTR Value 20K
SYMBOL res -24 224 R90
SYMATTR InstName R5
SYMATTR Value 1K
SYMBOL NMOS 8 32 R0
SYMATTR InstName Q1
SYMATTR Value BSC42DN25NS3
SYMBOL res -40 96 R90
SYMATTR InstName R6
SYMATTR Value 10
SYMBOL res -968 -32 R0
SYMATTR InstName R7
SYMATTR Value 125K
SYMBOL cap -872 -96 R0
SYMATTR InstName C4
SYMATTR Value .0022
SYMBOL cap -648 -96 R0
SYMATTR InstName C5
SYMATTR Value 100p
SYMBOL schottky -696 -128 R90
SYMATTR InstName D1
SYMATTR Value BAT54
SYMBOL cap -216 -32 R0
SYMATTR InstName C6
SYMATTR Value 22
SYMBOL res -56 -64 R90
SYMATTR InstName R8
SYMATTR Value 39
SYMBOL schottky 8 -64 R90
SYMATTR InstName D2
SYMATTR Value BAT54
SYMBOL res -248 -384 R0
SYMATTR InstName R9
SYMATTR Value 1.32Meg
SYMBOL res 40 -416 R0
SYMATTR InstName R10
SYMATTR Value 660K
SYMBOL cap -72 -400 R0
SYMATTR InstName C7
SYMATTR Value 470p
SYMBOL ind2 328 -352 M0
SYMATTR InstName L1
SYMATTR Value 20
SYMATTR SpiceLine Rser=.05
SYMBOL ind2 232 -112 R0
SYMATTR InstName L2
SYMATTR Value 16
SYMATTR Value2 Rser=.1
SYMBOL ind2 232 -240 M180
SYMATTR InstName L3
SYMATTR Value 100
SYMATTR SpiceLine Rser=.05
SYMBOL schottky 408 -368 M90
SYMATTR InstName D3
SYMATTR Value MBRS340
SYMBOL ind 552 -336 R270
SYMATTR InstName L4
SYMATTR Value 1
SYMBOL polcap 680 -336 R0
SYMATTR InstName C8
SYMATTR Value 3.3
SYMBOL res 808 -352 R0
SYMATTR InstName R11
SYMATTR Value 750
SYMBOL VOLTAGE -712 -432 R0
SYMATTR InstName V1
SYMATTR Value 200
SYMBOL zener -312 -224 M270
SYMATTR InstName D4
SYMATTR Value BZX84C15L
SYMBOL diode 40 -224 M180
SYMATTR InstName D5
SYMATTR Value MURS320
SYMBOL res -456 -128 R90
SYMATTR InstName R12
SYMATTR Value 510
SYMBOL res -440 -416 R0
SYMATTR InstName R13
SYMATTR Value 400K
SYMBOL PowerProducts\\LT1243 -424 176 R0
SYMATTR InstName U1
SYMBOL cap -248 256 R0
SYMATTR InstName C9
SYMATTR Value 25p
SYMBOL current -616 -240 R270
SYMATTR InstName I1
SYMATTR Value pwl(0 0 50u 7 100u 0)
SYMBOL polcap 504 -336 R0
SYMATTR InstName C10
SYMATTR Value 10
SYMATTR SpiceLine Rser=.1
SYMBOL res 952 -352 R0
SYMATTR InstName Rload
SYMATTR Value 25