Electrical – Getting following error in LTSpice simulation : “Too few nodes…”

dc/dc converterltspice

I am doing simulation of the following schematic of DC to DC converter in LTSpice.

When I click "Run" option , I am getting the following error "Too few nodes….".
What should I do?

.asc file:

Version 4
SHEET 1 1668 968
WIRE 864 -800 768 -800
WIRE 1008 -800 928 -800
WIRE -368 -736 -512 -736
WIRE -240 -736 -368 -736
WIRE -16 -736 -240 -736
WIRE 112 -736 -16 -736
WIRE 240 -736 112 -736
WIRE 544 -736 240 -736
WIRE -240 -704 -240 -736
WIRE -16 -704 -16 -736
WIRE 112 -704 112 -736
WIRE 240 -704 240 -736
WIRE -512 -688 -512 -736
WIRE -368 -688 -368 -736
WIRE 768 -672 768 -800
WIRE 768 -672 608 -672
WIRE 864 -672 768 -672
WIRE 1008 -672 1008 -800
WIRE 1008 -672 928 -672
WIRE 1056 -672 1008 -672
WIRE 1152 -672 1056 -672
WIRE 1248 -672 1152 -672
WIRE 1504 -672 1248 -672
WIRE 1616 -672 1504 -672
WIRE 544 -656 416 -656
WIRE 544 -608 480 -608
WIRE 704 -592 608 -592
WIRE 1056 -592 1056 -672
WIRE -240 -576 -240 -624
WIRE 480 -576 480 -608
WIRE 704 -560 704 -592
WIRE -512 -544 -512 -608
WIRE -432 -544 -512 -544
WIRE -368 -544 -368 -624
WIRE -368 -544 -432 -544
WIRE -16 -528 -16 -624
WIRE 112 -528 112 -624
WIRE 112 -528 -16 -528
WIRE 240 -528 240 -640
WIRE 240 -528 112 -528
WIRE 304 -528 240 -528
WIRE 416 -528 416 -656
WIRE 416 -528 368 -528
WIRE 544 -528 480 -528
WIRE -432 -512 -432 -544
WIRE 1056 -496 1056 -528
WIRE 1616 -464 1616 -672
WIRE 480 -432 480 -528
WIRE 480 -432 336 -432
WIRE 336 -384 336 -432
WIRE -704 -320 -880 -320
WIRE -880 -256 -880 -320
WIRE -240 -256 -240 -496
WIRE -80 -256 -240 -256
WIRE 32 -256 -80 -256
WIRE 112 -256 32 -256
WIRE 192 -256 112 -256
WIRE 336 -256 336 -320
WIRE 336 -256 272 -256
WIRE -80 -192 -80 -256
WIRE 32 -192 32 -256
WIRE 112 -192 112 -256
WIRE -880 -144 -880 -192
WIRE -1152 -80 -1664 -80
WIRE -704 -80 -704 -320
WIRE -704 -80 -1152 -80
WIRE -528 -80 -704 -80
WIRE -240 -80 -240 -256
WIRE -240 -80 -368 -80
WIRE -80 -80 -80 -128
WIRE 32 -80 32 -128
WIRE 112 -80 112 -128
WIRE 416 -80 416 -528
WIRE -1456 -48 -1568 -48
WIRE -1264 -48 -1456 -48
WIRE -528 -48 -1264 -48
WIRE -208 -32 -368 -32
WIRE -528 -16 -992 -16
WIRE 1504 -16 1504 -672
WIRE -528 0 -672 0
WIRE -240 0 -368 0
WIRE -208 0 -208 -32
WIRE 64 0 -208 0
WIRE 368 0 144 0
WIRE -1152 32 -1152 -80
WIRE -528 32 -592 32
WIRE -240 48 -240 0
WIRE -1456 64 -1456 -48
WIRE -864 64 -912 64
WIRE -736 64 -800 64
WIRE -1264 80 -1264 -48
WIRE -1216 80 -1264 80
WIRE -992 112 -992 -16
WIRE -912 112 -912 64
WIRE -912 112 -992 112
WIRE -736 112 -736 64
WIRE -672 112 -672 0
WIRE -672 112 -736 112
WIRE 416 128 416 16
WIRE 416 128 240 128
WIRE -1568 160 -1568 -48
WIRE -912 160 -912 112
WIRE -864 160 -912 160
WIRE -784 160 -800 160
WIRE -736 160 -736 112
WIRE -736 160 -784 160
WIRE -1152 176 -1152 128
WIRE 416 176 416 128
WIRE -1152 288 -1152 256
WIRE -592 288 -592 32
WIRE -592 288 -1152 288
WIRE -192 288 -592 288
WIRE 64 288 -192 288
WIRE 240 288 240 128
WIRE 240 288 144 288
WIRE 672 288 544 288
WIRE 720 288 672 288
WIRE 1152 288 1152 -672
WIRE 1152 288 720 288
WIRE 416 320 416 256
WIRE -192 352 -192 288
WIRE 544 400 544 288
WIRE 720 416 720 288
WIRE 768 416 720 416
WIRE 912 416 848 416
WIRE 992 416 912 416
WIRE 992 432 992 416
WIRE 912 464 912 416
WIRE -192 480 -192 416
WIRE 672 480 672 288
WIRE 1072 512 1024 512
WIRE 1248 512 1136 512
WIRE -1664 560 -1664 -80
WIRE -1568 560 -1568 240
WIRE -1568 560 -1664 560
WIRE 384 560 -1568 560
WIRE 544 560 544 480
WIRE 544 560 448 560
WIRE -992 592 -992 112
WIRE -368 592 -992 592
WIRE 224 592 -288 592
WIRE 384 592 224 592
WIRE 672 592 672 560
WIRE 672 592 448 592
WIRE 912 592 912 528
WIRE 912 592 672 592
WIRE 960 592 912 592
WIRE 1024 592 1024 512
WIRE 1024 592 960 592
WIRE 1072 592 1024 592
WIRE 1248 592 1248 512
WIRE 1248 592 1152 592
WIRE 1312 592 1248 592
WIRE 1504 592 1504 64
WIRE 1504 592 1376 592
WIRE 224 656 224 592
WIRE 960 736 960 592
WIRE 1072 736 960 736
WIRE 1504 768 1504 592
WIRE 1504 768 1152 768
WIRE 224 784 224 736
WIRE 1072 784 960 784
WIRE 1504 816 1504 768
WIRE 960 912 960 784
WIRE 1504 912 1504 896
WIRE 1504 912 960 912
WIRE 1504 928 1504 912
FLAG -432 -512 0
FLAG 480 -576 0
FLAG 112 -80 0
FLAG 32 -80 0
FLAG -80 -80 0
FLAG -240 48 0
FLAG -192 480 0
FLAG 704 -560 0
FLAG 1056 -496 0
FLAG 224 784 0
FLAG 992 496 0
FLAG 1504 928 0
FLAG -880 -144 0
FLAG 416 320 0
FLAG -1456 128 0
FLAG 1248 -672 Vout
SYMBOL voltage -512 -704 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName Vin
SYMATTR Value 110
SYMBOL polcap -384 -688 R0
WINDOW 3 24 56 Left 2
SYMATTR Value 1µ
SYMATTR InstName Cin
SYMATTR Description Capacitor
SYMATTR Type cap
SYMATTR SpiceLine V=16 Irms=0 Rser=7.08m Lser=0
SYMBOL res -256 -720 R0
SYMATTR InstName Rstartup_1
SYMATTR Value 75K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res -256 -592 R0
SYMATTR InstName Rstartup_2
SYMATTR Value 75K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res -32 -720 R0
SYMATTR InstName Rsnub2
SYMATTR Value 110K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL res 96 -720 R0
SYMATTR InstName Rsnub1
SYMATTR Value 110K
SYMATTR SpiceLine tol=1 pwr=0.1
SYMBOL cap 224 -704 R0
SYMATTR InstName Csnub
SYMATTR Value 0.0018µ
SYMATTR SpiceLine V=200 Irms=119m Rser=1.59882 Lser=0 mfg="KEMET" pn="C0805C182K2RAC" type="X7R"
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

Best Answer

That UCC28C40 library is encrypted. It works only with the appropriate version of PSpice.

However, as mentioned by Steve G, TI also offers an unencrypted model.

Related Solutions

Electronic – LTSpice D flip-flop not working

If you go to the LTspice help and navigate to "Special Functions" you'll see a list of parameters that can be selected for the digital components, including the Dflop.

Your shift register didn't work because it had no output rise or fall time associated with it, so everything was happening all at once!

Also, the digital stuff defaults to a Vcc of 1 volt.

I've redrawn your schematic so everything starts cleared, Vcc is 5 volts, and put some delay into the Dflops, and now it works. :)

If you right-click on any of the dflops, that'll bring up the attribute editor, which will show their edited (non-default) parameters, specifically:

SpiceLine = Vhigh 5 Trise 10n

and will allow you to modify any of the component's editable attributes.

Here's the schematic and the plot, which I edited to look like a timing diagram:

and here's the circuit list:

Version 4
SHEET 1 1732 752
WIRE 48 -144 -256 -144
WIRE 352 -144 48 -144
WIRE 656 -144 352 -144
WIRE 864 -144 656 -144
WIRE 1104 -144 864 -144
WIRE 1360 -144 1104 -144
WIRE 1616 -144 1360 -144
WIRE -128 -64 -368 -64
WIRE 176 -64 -64 -64
WIRE 480 -64 240 -64
WIRE 784 -64 544 -64
WIRE 864 -64 864 -144
WIRE -256 0 -256 -144
WIRE 48 0 48 -144
WIRE 352 0 352 -144
WIRE 656 0 656 -144
WIRE 1104 0 1104 -144
WIRE 1360 0 1360 -144
WIRE 1616 0 1616 -144
WIRE -368 48 -368 -64
WIRE -336 48 -368 48
WIRE -160 48 -176 48
WIRE -64 48 -64 -64
WIRE -32 48 -64 48
WIRE 144 48 128 48
WIRE 240 48 240 -64
WIRE 272 48 240 48
WIRE 448 48 432 48
WIRE 544 48 544 -64
WIRE 576 48 544 48
WIRE 1024 48 736 48
WIRE 1280 48 1184 48
WIRE 1536 48 1440 48
WIRE 1728 48 1696 48
WIRE -336 96 -368 96
WIRE -128 96 -128 -64
WIRE -128 96 -160 96
WIRE -32 96 -128 96
WIRE 176 96 176 -64
WIRE 176 96 144 96
WIRE 272 96 176 96
WIRE 480 96 480 -64
WIRE 480 96 448 96
WIRE 576 96 480 96
WIRE 784 96 784 -64
WIRE 784 96 752 96
WIRE 1024 96 992 96
WIRE 1280 96 1248 96
WIRE 1536 96 1504 96
WIRE -368 208 -368 96
WIRE 992 208 992 96
WIRE 992 208 -368 208
WIRE 1248 208 1248 96
WIRE 1248 208 992 208
WIRE 1504 208 1504 96
WIRE 1504 208 1248 208
WIRE -256 288 -256 144
WIRE 48 288 48 144
WIRE 48 288 -256 288
WIRE 352 288 352 144
WIRE 352 288 48 288
WIRE 656 288 656 144
WIRE 656 288 352 288
WIRE 1104 288 1104 144
WIRE 1104 288 656 288
WIRE 1360 288 1360 144
WIRE 1360 288 1104 288
WIRE 1616 288 1616 144
WIRE 1616 288 1360 288
WIRE -368 336 -368 208
WIRE -256 336 -256 288
WIRE -368 448 -368 416
WIRE -256 448 -256 416
WIRE -256 448 -368 448
WIRE -368 512 -368 448
FLAG -368 512 0
FLAG 864 -64 0
SYMBOL voltage -368 320 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
WINDOW 3 86 297 Invisible 2
SYMATTR InstName V1
SYMATTR Value PULSE(0 5 1u 5n 5n 0.5u 1u)
SYMBOL voltage -256 320 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
WINDOW 3 86 297 Invisible 2
SYMATTR InstName V2
SYMATTR Value PULSE(0 5 0 50n 50n 100n)
SYMBOL Digital\\dflop -256 0 R0
SYMATTR InstName A1
SYMATTR SpiceLine Vhigh 5 Trise 10n
SYMBOL Digital\\dflop 48 0 R0
SYMATTR InstName A2
SYMATTR SpiceLine Vhigh 5 Trise 10n
SYMBOL Digital\\dflop 352 0 R0
SYMATTR InstName A3
SYMATTR SpiceLine Vhigh 5 Trise 10n
SYMBOL Digital\\dflop 656 0 R0
SYMATTR InstName A4
SYMATTR SpiceLine Vhigh 5 Trise 10n
SYMBOL Digital\\dflop 1104 0 R0
SYMATTR InstName A5
SYMATTR SpiceLine Vhigh 5 Trise 10n
SYMBOL Digital\\dflop 1360 0 R0
SYMATTR InstName A6
SYMATTR SpiceLine Vhigh 5 Trise 10n
SYMBOL Digital\\dflop 1616 0 R0
SYMATTR InstName A7
SYMATTR SpiceLine Vhigh 5 Trise 10n
TEXT -352 480 Left 2 !.tran 0 30us 0

Electrical – LTSpice Error: timestep too small

Your simulation is, for some reason, too hard for the solver. See this page for some guidance.

Simulators like this use numerical ordinary differential equation (ODE) solvers. Nearly all such solvers adjust the time step dynamically, trying for the largest possible time step while maintaining accuracy. So the time step gets small either when you're doing something that challenges the algorithm (like a stiff system), or when you're asking for too much (like the relative tolerance that @jrive) spoke of.

Things to try are to:

First, look at your schematic and ask yourself if you've just asked a nonsensical question
Second, try changing the solver. I'm not in the same room with an LTSpice application, but AFAIK it uses a Runga-Kutta solver, which doesn't do well with stiff systems (Google "stiff system simulation" for details). My favorite go-to in this case is the Gear solver. It is (I think!!!) in a menu selection marked "controls". They may also have a minimum time step that you can specify, at the expense of possibly screwing up the accuracy of your results.

Best Answer

Related Solutions

Electronic – LTSpice D flip-flop not working

Electrical – LTSpice Error: timestep too small

Related Topic