Estoy haciendo una simulación del siguiente esquema del convertidor de CC a CC en LTSpice.
Cuando hago clic en la opción "Ejecutar", aparece el siguiente error "Muy pocos nodos ...".
¿Qué debo hacer? 
archivo.asc:
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SYMBOL schottky 368 -544 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName Dsnub
SYMATTR Value RB056L-40
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL ind2 528 -752 R0
WINDOW 0 -33 39 Left 2
WINDOW 3 -28 74 Left 2
SYMATTR InstName L1
SYMBOL ind2 528 -624 R0
WINDOW 0 -27 35 Left 2
WINDOW 3 -19 73 Left 2
SYMATTR InstName L2
SYMBOL ind2 624 -576 R180
WINDOW 0 -29 76 Left 2
WINDOW 3 -19 49 Left 2
SYMATTR InstName L3
SYMBOL nmos 368 -80 R0
SYMATTR InstName M1
SYMBOL polcap -96 -192 R0
WINDOW 0 67 8 Right 2
WINDOW 3 24 56 Left 2
SYMATTR InstName C12
SYMATTR Value 100n
SYMATTR Description Capacitor
SYMATTR Type cap
SYMATTR SpiceLine V=6.3 Irms=0 Rser=0.9 Lser=0 mfg="AVX" pn="TAJD107M006" type="Tantalum"
SYMBOL zener 48 -128 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D12
SYMATTR Value UDZV18B
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL polcap 96 -192 R0
SYMATTR InstName Cvdd
SYMATTR Value 68µ
SYMATTR SpiceLine V=10 Irms=2.03852 Rser=0.045 Lser=0 mfg="KEMET" pn="T520V686M010ATE045" type="Tantalum"
SYMBOL res 288 -272 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName Raux
SYMATTR Value 10
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL schottky 320 -384 R0
SYMATTR InstName Daux
SYMATTR Value 1N5817
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL res 160 -16 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName Rdrv
SYMATTR Value 3.65
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 400 160 R0
SYMATTR InstName Rsnus
SYMATTR Value 1.78
SYMBOL cap -208 352 R0
WINDOW 3 26 53 Left 2
SYMATTR Value 470p
SYMATTR InstName Ccs
SYMBOL res 160 272 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName Rcs
SYMATTR Value 100k
SYMBOL schottky 864 -784 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D4
SYMATTR Value B520C
SYMBOL polcap 1040 -592 R0
SYMATTR InstName C4
SYMATTR Value 180µ
SYMATTR SpiceLine V=5 Irms=1.90488 Rser=0.011 Lser=0
SYMBOL res -272 576 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R13
SYMATTR Value 4.99k
SYMBOL res 208 640 R0
SYMATTR InstName R12
SYMATTR Value 1.62k
SYMBOL cap -800 48 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C13
SYMATTR Value 1n
SYMBOL res -768 144 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R11
SYMATTR Value 100k
SYMBOL npn2 -1216 32 R0
SYMATTR InstName Q1
SYMBOL res -1168 160 R0
SYMATTR InstName Rsc
SYMATTR Value 3.32k
SYMBOL cap -1472 64 R0
SYMATTR InstName Ct
SYMATTR Value 1n
SYMBOL res -1584 144 R0
SYMATTR InstName Rt
SYMATTR Value 17.4k
SYMBOL res 528 384 R0
SYMATTR InstName Rled
SYMATTR Value 2.05k
SYMBOL res 656 464 R0
SYMATTR InstName Rbias
SYMATTR Value 205
SYMBOL res 864 400 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R21
SYMATTR Value 10k
SYMBOL schottky 928 528 R180
WINDOW 0 24 64 Left 2
WINDOW 3 24 0 Left 2
SYMATTR InstName D5
SYMBOL cap 976 432 R0
SYMATTR InstName C21
SYMATTR Value 10µ
SYMBOL res 1168 576 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R22
SYMATTR Value 9.53k
SYMBOL cap 1136 496 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C22
SYMATTR Value 22p
SYMBOL cap 1376 576 R90
WINDOW 0 0 32 VBottom 2
WINDOW 3 32 32 VTop 2
SYMATTR InstName C23
SYMATTR Value 10n
SYMBOL res 1488 800 R0
SYMATTR InstName Rfbb
SYMATTR Value 1.43K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 1488 -32 R0
SYMATTR InstName Rfbt
SYMATTR Value 4.32K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL current 1616 -464 R0
SYMATTR InstName I1
SYMBOL polcap -896 -256 R0
WINDOW 3 24 56 Left 2
SYMATTR Value 100n
SYMATTR InstName Cref
SYMATTR Description Capacitor
SYMATTR Type cap
SYMATTR SpiceLine V=3 Irms=2.25389 Rser=0.025 Lser=0
SYMBOL schottky 864 -656 R270
WINDOW 0 32 32 VTop 2
WINDOW 3 0 32 VBottom 2
SYMATTR InstName D3
SYMATTR Value B520C
SYMBOL AutoGenerated\UCC28C40_START -448 -16 R0
SYMATTR InstName U2
SYMBOL AutoGenerated\TCMT1100 416 576 R0
SYMATTR InstName U1
SYMBOL AutoGenerated\TL431 1104 768 R0
SYMATTR InstName U3
TEXT -1664 952 Left 2 !.tran 15m
TEXT 504 -752 Left 2 !K1 L2 L1 L3 1