LT Spice, Dflop: I can set VHIGH = 5 and that works. But if I add TRISE = 500p then VHIGH reverts to 1 volt. And incidentally, what's the difference between Spice Line 1 and Spice Line 2? TRISE on either breaks VHIGH. Building a pseurandom bit stream generator is too much work, but it's easy to clock random junk into a flop.
dflop weirdness
Started by ●September 17, 2022
Reply by ●September 17, 20222022-09-17
lørdag den 17. september 2022 kl. 23.45.50 UTC+2 skrev John Larkin:> LT Spice, Dflop: > > I can set VHIGH = 5 and that works. > > But if I add TRISE = 500p then VHIGH reverts to 1 volt. >works just fine, Version 4 SHEET 1 880 680 WIRE 304 48 64 48 WIRE 64 160 64 48 WIRE 96 160 64 160 WIRE 96 208 -112 208 WIRE 304 208 304 48 WIRE 304 208 272 208 WIRE -112 240 -112 208 WIRE -112 400 -112 320 FLAG -112 400 0 SYMBOL Digital\\dflop 176 112 R0 WINDOW 3 156 69 Left 2 SYMATTR InstName A1 SYMATTR Value VHIGH=5,TRISE=10m SYMBOL voltage -112 224 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value SINE(2.5 2.5 10 0) TEXT -146 424 Left 2 !.tran 1
Reply by ●September 17, 20222022-09-17
On Sat, 17 Sep 2022 15:52:34 -0700 (PDT), Lasse Langwadt Christensen <langwadt@fonz.dk> wrote:>l�rdag den 17. september 2022 kl. 23.45.50 UTC+2 skrev John Larkin: >> LT Spice, Dflop: >> >> I can set VHIGH = 5 and that works. >> >> But if I add TRISE = 500p then VHIGH reverts to 1 volt. >> > >works just fine, > >Version 4 >SHEET 1 880 680 >WIRE 304 48 64 48 >WIRE 64 160 64 48 >WIRE 96 160 64 160 >WIRE 96 208 -112 208 >WIRE 304 208 304 48 >WIRE 304 208 272 208 >WIRE -112 240 -112 208 >WIRE -112 400 -112 320 >FLAG -112 400 0 >SYMBOL Digital\\dflop 176 112 R0 >WINDOW 3 156 69 Left 2 >SYMATTR InstName A1 >SYMATTR Value VHIGH=5,TRISE=10mI tried commas, no help. DFLOP is weird. I had rout=1m, and that messed it up. With rout=0.1, it's OK. The flop output with trise=700p has a soft corner. A pulsed voltage source with the same specified rise time is sharp.
Reply by ●September 18, 20222022-09-18
On Sunday, September 18, 2022 at 9:46:00 AM UTC+10, John Larkin wrote:> On Sat, 17 Sep 2022 15:52:34 -0700 (PDT), Lasse Langwadt Christensen > <lang...@fonz.dk> wrote: > > >lørdag den 17. september 2022 kl. 23.45.50 UTC+2 skrev John Larkin: > >> LT Spice, Dflop: > >> > >> I can set VHIGH = 5 and that works. > >> > >> But if I add TRISE = 500p then VHIGH reverts to 1 volt. > >> > > > >works just fine, > > > >Version 4 > >SHEET 1 880 680 > >WIRE 304 48 64 48 > >WIRE 64 160 64 48 > >WIRE 96 160 64 160 > >WIRE 96 208 -112 208 > >WIRE 304 208 304 48 > >WIRE 304 208 272 208 > >WIRE -112 240 -112 208 > >WIRE -112 400 -112 320 > >FLAG -112 400 0 > >SYMBOL Digital\\dflop 176 112 R0 > >WINDOW 3 156 69 Left 2 > >SYMATTR InstName A1 > >SYMATTR Value VHIGH=5,TRISE=10m > I tried commas, no help. > > DFLOP is weird. I had rout=1m, and that messed it up. With rout=0.1, > it's OK. > > The flop output with trise=700p has a soft corner. A pulsed voltage > source with the same specified rise time is sharp.No surprise there. The bistable model is supposed to simulated a real part, and the pulsed voltage source is a mathematical abstraction. -- Bill Sloman, Sydney