* SPICE netlist
R1 N017 0 .67
C1 N018 0 220p
C2 N015 0 .1
C3 N014 N013 .01
R2 N013 N010 100K
R3 N015 N018 12K
R4 N010 0 20K
R5 N017 N016 1K
MQ1 N004 N012 N017 N017 IRF7303
R6 N012 N011 12
R7 N006 N010 152K
C4 N006 0 .0022
C5 N007 0 100p
D1 N007 N006 BAT54
C6 N005 0 22
R8 N009 N005 39
D2 N008 N009 BAT54
R9 IN N016 1.32Meg
R10 IN N003 660K
C7 IN N003 470p
L1 N001 0 16 Rser=.05
L2 N008 0 18.8 Rser=.1
L3 N004 IN 100 Rser=.05
D3 N001 N002 MBRS340
C8 N002 0 10
L4 N002 +20V 1 Rpar=100
C9 +20V 0 3.3
R11 +20V 0 750
V1 IN 0 200
D4 0 N005 BZX84C15L
D5 N004 N003 MURS320
R12 N008 N007 510
R13 IN N005 400K
XU1 N014 N010 N016 N018 0 N011 N005 N015 LT1245 ;pnba COMP)FB)Isense)Rt/Ct)GND)Output)Vcc)Vref
C10 N016 0 50p
Rload +20V 0 50
.tran 1m
K1 L1 L2 L3 1

* LTspice schematic (.asc)
Version 4
SHEET 1 1920 816
WIRE -416 -408 -560 -408
WIRE -224 -408 -416 -408
WIRE 0 -408 -224 -408
WIRE 112 -408 0 -408
WIRE 240 -408 112 -408
WIRE -560 -392 -560 -408
WIRE -416 -392 -416 -408
WIRE 0 -392 0 -408
WIRE 112 -392 112 -408
WIRE 240 -360 240 -408
WIRE 304 -360 240 -360
WIRE 464 -360 368 -360
WIRE 576 -360 528 -360
WIRE 624 -360 576 -360
WIRE 752 -360 704 -360
WIRE 848 -360 752 -360
WIRE 960 -360 848 -360
WIRE 304 -344 304 -360
WIRE 368 -344 368 -360
WIRE 576 -344 576 -360
WIRE 752 -344 752 -360
WIRE 848 -344 848 -360
WIRE 960 -344 960 -360
WIRE -560 -296 -560 -312
WIRE 0 -296 0 -328
WIRE 112 -296 112 -312
WIRE 112 -296 0 -296
WIRE -224 -280 -224 -408
WIRE 112 -280 112 -296
WIRE 304 -248 304 -264
WIRE 304 -248 240 -248
WIRE 368 -248 368 -264
WIRE 576 -248 576 -280
WIRE 576 -248 368 -248
WIRE 752 -248 752 -280
WIRE 752 -248 576 -248
WIRE 848 -248 848 -264
WIRE 848 -248 752 -248
WIRE 960 -248 960 -264
WIRE 960 -248 848 -248
WIRE -528 -232 -576 -232
WIRE -416 -232 -416 -312
WIRE -416 -232 -464 -232
WIRE 960 -232 960 -248
WIRE 112 -200 112 -216
WIRE 240 -200 240 -248
WIRE 240 -200 112 -200
WIRE -848 -136 -944 -136
WIRE -752 -136 -848 -136
WIRE -624 -136 -688 -136
WIRE -544 -136 -624 -136
WIRE 48 -136 -464 -136
WIRE 304 -136 48 -136
WIRE -848 -120 -848 -136
WIRE -624 -120 -624 -136
WIRE 304 -120 304 -136
WIRE -944 -104 -944 -136
WIRE -416 -72 -416 -232
WIRE -192 -72 -416 -72
WIRE -128 -72 -192 -72
WIRE -32 -72 -48 -72
WIRE 48 -72 48 -136
WIRE 48 -72 32 -72
WIRE -192 -56 -192 -72
WIRE -848 -24 -848 -56
WIRE -624 -24 -624 -56
WIRE 304 -24 304 -40
WIRE -416 -8 -416 -72
WIRE 112 8 112 -200
WIRE -192 40 -192 8
WIRE -944 56 -944 -24
WIRE -576 56 -944 56
WIRE -128 88 -256 88
WIRE 64 88 -48 88
WIRE -944 120 -944 56
WIRE -816 120 -944 120
WIRE -688 120 -736 120
WIRE -576 120 -624 120
WIRE -944 136 -944 120
WIRE -720 184 -832 184
WIRE -576 184 -720 184
WIRE -832 200 -832 184
WIRE -720 200 -720 184
WIRE -224 216 -224 -200
WIRE -224 216 -256 216
WIRE -144 216 -224 216
WIRE 112 216 112 104
WIRE 112 216 -64 216
WIRE -944 232 -944 216
WIRE -224 232 -224 216
WIRE 112 232 112 216
WIRE -576 248 -624 248
WIRE -720 280 -720 264
WIRE -832 312 -832 280
WIRE -624 312 -624 248
WIRE -624 312 -832 312
WIRE -224 312 -224 296
WIRE -832 328 -832 312
WIRE -416 328 -416 312
WIRE 112 328 112 312
WIRE -832 408 -832 392
FLAG 112 328 0
FLAG -832 408 0
FLAG -720 280 0
FLAG -944 232 0
FLAG -416 328 0
FLAG -848 -24 0
FLAG -624 -24 0
FLAG -192 40 0
FLAG 304 -24 0
FLAG -560 -296 0
FLAG -576 -232 0
FLAG 960 -360 +20V
FLAG 960 -232 0
FLAG -224 312 0
FLAG -560 -408 IN
SYMBOL RES 96 216 R0
SYMATTR InstName R1
SYMATTR Value .67
SYMBOL cap -848 328 R0
SYMATTR InstName C1
SYMATTR Value 220p
SYMBOL cap -736 200 R0
SYMATTR InstName C2
SYMATTR Value .1
SYMBOL cap -624 104 R90
SYMATTR InstName C3
SYMATTR Value .01
SYMBOL res -720 104 R90
SYMATTR InstName R2
SYMATTR Value 100K
SYMBOL res -848 184 R0
SYMATTR InstName R3
SYMATTR Value 12K
SYMBOL res -960 120 R0
SYMATTR InstName R4
SYMATTR Value 20K
SYMBOL res -48 200 R90
SYMATTR InstName R5
SYMATTR Value 1K
SYMBOL NMOS 64 8 R0
SYMATTR InstName Q1
SYMATTR Value IRF7303
SYMBOL res -32 72 R90
SYMATTR InstName R6
SYMATTR Value 12
SYMBOL res -960 -120 R0
SYMATTR InstName R7
SYMATTR Value 152K
SYMBOL cap -864 -120 R0
SYMATTR InstName C4
SYMATTR Value .0022
SYMBOL cap -640 -120 R0
SYMATTR InstName C5
SYMATTR Value 100p
SYMBOL schottky -688 -152 R90
SYMATTR InstName D1
SYMATTR Value BAT54
SYMBOL cap -208 -56 R0
SYMATTR InstName C6
SYMATTR Value 22
SYMBOL res -32 -88 R90
SYMATTR InstName R8
SYMATTR Value 39
SYMBOL schottky 32 -88 R90
SYMATTR InstName D2
SYMATTR Value BAT54
SYMBOL res -240 -296 R0
SYMATTR InstName R9
SYMATTR Value 1.32Meg
SYMBOL res 96 -408 R0
SYMATTR InstName R10
SYMATTR Value 660K
SYMBOL cap -16 -392 R0
SYMATTR InstName C7
SYMATTR Value 470p
SYMBOL ind2 384 -360 M0
SYMATTR InstName L1
SYMATTR Value 16
SYMATTR SpiceLine Rser=.05
SYMBOL ind2 288 -136 R0
SYMATTR InstName L2
SYMATTR Value 18.8
SYMATTR SpiceLine Rser=.1
SYMBOL ind2 288 -248 M180
SYMATTR InstName L3
SYMATTR Value 100
SYMATTR SpiceLine Rser=.05
SYMBOL schottky 464 -376 M90
SYMATTR InstName D3
SYMATTR Value MBRS340
SYMBOL cap 560 -344 R0
SYMATTR InstName C8
SYMATTR Value 10
SYMBOL ind 608 -344 R270
SYMATTR InstName L4
SYMATTR Value 1
SYMATTR SpiceLine Rpar=100
SYMBOL polcap 736 -344 R0
SYMATTR InstName C9
SYMATTR Value 3.3
SYMBOL res 832 -360 R0
SYMATTR InstName R11
SYMATTR Value 750
SYMBOL VOLTAGE -560 -408 R0
SYMATTR InstName V1
SYMATTR Value 200
SYMBOL zener -528 -216 R270
SYMATTR InstName D4
SYMATTR Value BZX84C15L
SYMBOL diode 96 -216 M180
SYMATTR InstName D5
SYMATTR Value MURS320
SYMBOL res -448 -152 R90
SYMATTR InstName R12
SYMATTR Value 510
SYMBOL res -432 -408 R0
SYMATTR InstName R13
SYMATTR Value 400K
SYMBOL PowerProducts\\LT1245 -416 152 R0
SYMATTR InstName U1
SYMBOL cap -240 232 R0
SYMATTR InstName C10
SYMATTR Value 50p
SYMBOL res 944 -360 R0
SYMATTR InstName Rload
SYMATTR Value 50