dflop weirdness...

[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.


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.

 

[Lasse Langwadt Christensen]

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

 

[John Larkin]

On Sat, 17 Sep 2022 15:52:34 -0700 (PDT), Lasse Langwadt Christensen
<langwadt@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.

 

[Anthony William Sloman]

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