Reply by Jim Thompson ●March 25, 20112011-03-25
On Thu, 24 Mar 2011 23:20:24 -0700, josephkk
<joseph_barrett@sbcglobal.net> wrote:


>On Sat, 19 Mar 2011 01:01:39 -0700 (PDT), whit3rd <whit3rd@gmail.com>
>wrote:
>
>>On Friday, March 18, 2011 5:15:23 PM UTC-7, Helmut Sennewald wrote:
>>> "Jim Thompson" <To-Email-Use-Th...@On-My-Web-Site.com> schrieb 
>>> im Newsbeitrag news:bus7o6drmsa2vbhrtajn2gsalp6qrcinqf@4ax.com...
>>> > On Sat, 19 Mar 2011 00:52:38 +0100, "Helmut Sennewald"
>>> > <helmuts...@t-online.de> wrote:
>>> >
>>> >>"Jim Thompson" <To-Email-Use-Th...@On-My-Web-Site.com> schrieb
>>> >>im Newsbeitrag news:tep7o6p6m5phjofimc1336tulv7919h7ht@4ax.com...
>>> >>> Got annoyed at the flaky 555 models that are out there, so I rolled my
>>> >>> own...
>>> >>>
>>> >>> http://www.analog-innovations.com/SED/MyLMC555.zip
>>> >>>
>>> >>> Based on old AMI 20V CMOS device models
>>
>>> I have to use ".ic V(timing_cap)=0" to get the simulation quickly started.
>>
>>It's possible that would miss some real behaviors, of course; could the
>>flip-flop transistors get some explicit gate capacitors?  Those would hold the
>>state info of the flip-flop, and allow the initial timing cap charges of
>>low, medium,  high, to have different initial effects.


The timing cap is what Helmut had to set a .IC, because .TRAN
simulations don't have the noise of the real world.  So "flip-flops"
(weak plus strong inverter in this case) can queue up balance in the
simulator.


>>
>>I'm curious, why is the differential amplifier 'tanh'?  That isn't the
>>analytic form for square-law MOSFETs, is it?
>
>It is standard for base input, collector output bipolar differential pairs
>for sure.  Had to grind the physics for my semiconductor physics course.
>8:-P


I use TANH a lot in my behavioral stuff because all derivatives exist,
so convergence in a simulator is easy.
		
                                        ...Jim Thompson
-- 
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

      Remember: Once you go over the hill, you pick up speed
Reply by John Fields ●March 25, 20112011-03-25
On Thu, 24 Mar 2011 23:24:52 +0100, "Helmut Sennewald"
<helmutsennewald@t-online.de> wrote:


>"John Fields" <jfields@austininstruments.com> schrieb im Newsbeitrag 
>news:hdcno6ptlutkbpnekqprakhet3i7ot06qc@4ax.com...
>> On Thu, 24 Mar 2011 12:33:07 -0400, Bitrex
>> <bitrex@de.lete.earthlink.net> wrote:
>>>I don't believe the bipolar 555 model included with LTSpice is
>>>modeling the supply spikes accurately.
>> ....
>> I've just posted a query to:
>> http://groups.yahoo.com/group/LTspice/
>> for clarification re. the accuracy of the model, and I'll post what
>> comes back as soon as I get it.
>> Maybe Helmut will post here first.
>> -- 
>> JF
>
>
>Hello John,
>
>The NE555 in the Misc-folder of LTspice may be just a gift from Mike.
>I guess he made it because so many people asked for a 555.
>LTC doesn't have a 555. So we can't expect that Mike spends
>time to tweak the model for shoot-through current.
>
>I tried a little bit with a capacitive load. Adding 100pF
>to the output has given a significant current peak in the
>power supply (V-source). Maybe this is a reasonable workaround
>if somebody wants it more realistic..
>
>Best regards,
>Helmut
>

---
Hello Helmut,

Thanks. :-)

-- 
JF
Reply by josephkk ●March 25, 20112011-03-25
On Sat, 19 Mar 2011 01:01:39 -0700 (PDT), whit3rd <whit3rd@gmail.com>
wrote:


>On Friday, March 18, 2011 5:15:23 PM UTC-7, Helmut Sennewald wrote:
>> "Jim Thompson" <To-Email-Use-Th...@On-My-Web-Site.com> schrieb=20
>> im Newsbeitrag news:bus7o6drmsa2vbhrtajn2gsalp6qrcinqf@4ax.com...
>> > On Sat, 19 Mar 2011 00:52:38 +0100, "Helmut Sennewald"
>> > <helmuts...@t-online.de> wrote:
>> >
>> >>"Jim Thompson" <To-Email-Use-Th...@On-My-Web-Site.com> schrieb
>> >>im Newsbeitrag news:tep7o6p6m5phjofimc1336tulv7919h7ht@4ax.com...
>> >>> Got annoyed at the flaky 555 models that are out there, so I =

rolled my

>> >>> own...
>> >>>
>> >>> http://www.analog-innovations.com/SED/MyLMC555.zip
>> >>>
>> >>> Based on old AMI 20V CMOS device models
>
>> I have to use ".ic V(timing_cap)=3D0" to get the simulation quickly =

started.

>
>It's possible that would miss some real behaviors, of course; could the
>flip-flop transistors get some explicit gate capacitors?  Those would =

hold the

>state info of the flip-flop, and allow the initial timing cap charges of
>low, medium,  high, to have different initial effects.
>
>I'm curious, why is the differential amplifier 'tanh'?  That isn't the
>analytic form for square-law MOSFETs, is it?


It is standard for base input, collector output bipolar differential =
pairs
for sure.  Had to grind the physics for my semiconductor physics course.
8:-P
Reply by John Fields ●March 24, 20112011-03-24
On Thu, 24 Mar 2011 23:24:52 +0100, "Helmut Sennewald"
<helmutsennewald@t-online.de> wrote:


>"John Fields" <jfields@austininstruments.com> schrieb im Newsbeitrag 
>news:hdcno6ptlutkbpnekqprakhet3i7ot06qc@4ax.com...
>> On Thu, 24 Mar 2011 12:33:07 -0400, Bitrex
>> <bitrex@de.lete.earthlink.net> wrote:
>>>I don't believe the bipolar 555 model included with LTSpice is
>>>modeling the supply spikes accurately.
>> ....
>> I've just posted a query to:
>> http://groups.yahoo.com/group/LTspice/
>> for clarification re. the accuracy of the model, and I'll post what
>> comes back as soon as I get it.
>> Maybe Helmut will post here first.
>> -- 
>> JF
>
>
>Hello John,
>
>The NE555 in the Misc-folder of LTspice may be just a gift from Mike.
>I guess he made it because so many people asked for a 555.
>LTC doesn't have a 555. So we can't expect that Mike spends
>time to tweak the model for shoot-through current.
>
>I tried a little bit with a capacitive load. Adding 100pF
>to the output has given a significant current peak in the
>power supply (V-source). Maybe this is a reasonable workaround
>if somebody wants it more realistic..
>
>Best regards,
>Helmut


---
Hello Helmut,

As always, with you, reason prevails. :-)

Thank you for your advice.

-- 
JF
Reply by Helmut Sennewald ●March 24, 20112011-03-24
"John Fields" <jfields@austininstruments.com> schrieb im Newsbeitrag 
news:hdcno6ptlutkbpnekqprakhet3i7ot06qc@4ax.com...

> On Thu, 24 Mar 2011 12:33:07 -0400, Bitrex
> <bitrex@de.lete.earthlink.net> wrote:
>>I don't believe the bipolar 555 model included with LTSpice is
>>modeling the supply spikes accurately.
> ....
> I've just posted a query to:
> http://groups.yahoo.com/group/LTspice/
> for clarification re. the accuracy of the model, and I'll post what
> comes back as soon as I get it.
> Maybe Helmut will post here first.
> -- 
> JF



Hello John,

The NE555 in the Misc-folder of LTspice may be just a gift from Mike.
I guess he made it because so many people asked for a 555.
LTC doesn't have a 555. So we can't expect that Mike spends
time to tweak the model for shoot-through current.

I tried a little bit with a capacitive load. Adding 100pF
to the output has given a significant current peak in the
power supply (V-source). Maybe this is a reasonable workaround
if somebody wants it more realistic..

Best regards,
Helmut
Reply by Jim Thompson ●March 24, 20112011-03-24
On Thu, 24 Mar 2011 16:06:23 -0500, John Fields
<jfields@austininstruments.com> wrote:


>On Thu, 24 Mar 2011 12:33:07 -0400, Bitrex
><bitrex@de.lete.earthlink.net> wrote:
>
>.
>.
>.
>
>>I don't believe the bipolar 555 model included with LTSpice is 
>>modeling the supply spikes accurately.
>
>---
>Here's the circuit I'm using to test Linear's NE555 model:
>
>Version 4
>SHEET 1 880 748
>WIRE 224 192 -128 192
>WIRE 544 192 448 192
>WIRE -128 256 -128 192
>WIRE -80 256 -128 256
>WIRE 32 256 0 256
>WIRE 64 256 32 256
>WIRE 224 256 144 256
>WIRE 512 256 448 256
>WIRE 32 320 32 256
>WIRE 176 320 32 320
>WIRE 224 320 176 320
>WIRE 608 320 448 320
>WIRE 480 384 448 384
>WIRE 608 416 608 320
>WIRE 176 480 176 320
>WIRE 512 480 512 256
>WIRE 512 480 176 480
>WIRE 544 496 544 192
>WIRE -128 512 -128 256
>WIRE 480 512 480 384
>WIRE 480 512 -128 512
>WIRE -128 528 -128 512
>WIRE 176 544 176 480
>WIRE -128 624 -128 608
>WIRE 176 624 176 608
>WIRE 176 624 -128 624
>WIRE 544 624 544 576
>WIRE 544 624 176 624
>WIRE 608 624 608 496
>WIRE 608 624 544 624
>WIRE -128 688 -128 624
>FLAG -128 688 0
>SYMBOL Misc\\NE555 336 288 M0
>SYMATTR InstName U1
>SYMBOL voltage -128 512 M0
>WINDOW 123 0 0 Left 0
>WINDOW 39 0 0 Left 0
>SYMATTR InstName V1
>SYMATTR Value 5
>SYMBOL res -96 240 M90
>WINDOW 0 0 56 VBottom 0
>WINDOW 3 32 58 VTop 0
>SYMATTR InstName R1
>SYMATTR Value 40k
>SYMBOL res 48 240 M90
>WINDOW 0 0 56 VBottom 0
>WINDOW 3 32 56 VTop 0
>SYMATTR InstName R2
>SYMATTR Value 19.8k
>SYMBOL res 624 400 M0
>WINDOW 0 -45 40 Left 0
>WINDOW 3 -59 71 Left 0
>SYMATTR InstName R3
>SYMATTR Value 1000
>SYMBOL cap 192 544 M0
>WINDOW 0 -33 32 Left 0
>WINDOW 3 -39 58 Left 0
>SYMATTR InstName C1
>SYMATTR Value 1e-7
>SYMBOL res 528 480 R0
>SYMATTR InstName R4
>SYMATTR Value 1
>TEXT 88 656 Right 0 !.tran .1 startup uic
>TEXT 456 176 Left 0 ;1
>TEXT 456 240 Left 0 ;2
>TEXT 456 304 Left 0 ;3
>TEXT 456 360 Left 0 ;4
>TEXT 200 368 Left 0 ;5
>TEXT 200 304 Left 0 ;6
>TEXT 200 240 Left 0 ;7
>TEXT 200 176 Left 0 ;8
>
>
>I've just posted a query to:
>
> http://groups.yahoo.com/group/LTspice/
>
>for clarification re. the accuracy of the model, and I'll post what
>comes back as soon as I get it.
>
>Maybe Helmut will post here first.


The NE555 model in LTspice is virtually all behavioral modeling.  Just
a quick observation of the switches (6 Ohms) suggest a whopping spike
;-)
		
                                        ...Jim Thompson
-- 
| James E.Thompson, CTO                            |    mens     |
| Analog Innovations, Inc.                         |     et      |
| Analog/Mixed-Signal ASIC's and Discrete Systems  |    manus    |
| Phoenix, Arizona  85048    Skype: Contacts Only  |             |
| Voice:(480)460-2350  Fax: Available upon request |  Brass Rat  |
| E-mail Icon at http://www.analog-innovations.com |    1962     |

      Remember: Once you go over the hill, you pick up speed
Reply by John Fields ●March 24, 20112011-03-24
On Thu, 24 Mar 2011 12:33:07 -0400, Bitrex
<bitrex@de.lete.earthlink.net> wrote:

.
.
.


>I don't believe the bipolar 555 model included with LTSpice is 
>modeling the supply spikes accurately.


---
Here's the circuit I'm using to test Linear's NE555 model:

Version 4
SHEET 1 880 748
WIRE 224 192 -128 192
WIRE 544 192 448 192
WIRE -128 256 -128 192
WIRE -80 256 -128 256
WIRE 32 256 0 256
WIRE 64 256 32 256
WIRE 224 256 144 256
WIRE 512 256 448 256
WIRE 32 320 32 256
WIRE 176 320 32 320
WIRE 224 320 176 320
WIRE 608 320 448 320
WIRE 480 384 448 384
WIRE 608 416 608 320
WIRE 176 480 176 320
WIRE 512 480 512 256
WIRE 512 480 176 480
WIRE 544 496 544 192
WIRE -128 512 -128 256
WIRE 480 512 480 384
WIRE 480 512 -128 512
WIRE -128 528 -128 512
WIRE 176 544 176 480
WIRE -128 624 -128 608
WIRE 176 624 176 608
WIRE 176 624 -128 624
WIRE 544 624 544 576
WIRE 544 624 176 624
WIRE 608 624 608 496
WIRE 608 624 544 624
WIRE -128 688 -128 624
FLAG -128 688 0
SYMBOL Misc\\NE555 336 288 M0
SYMATTR InstName U1
SYMBOL voltage -128 512 M0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL res -96 240 M90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 58 VTop 0
SYMATTR InstName R1
SYMATTR Value 40k
SYMBOL res 48 240 M90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R2
SYMATTR Value 19.8k
SYMBOL res 624 400 M0
WINDOW 0 -45 40 Left 0
WINDOW 3 -59 71 Left 0
SYMATTR InstName R3
SYMATTR Value 1000
SYMBOL cap 192 544 M0
WINDOW 0 -33 32 Left 0
WINDOW 3 -39 58 Left 0
SYMATTR InstName C1
SYMATTR Value 1e-7
SYMBOL res 528 480 R0
SYMATTR InstName R4
SYMATTR Value 1
TEXT 88 656 Right 0 !.tran .1 startup uic
TEXT 456 176 Left 0 ;1
TEXT 456 240 Left 0 ;2
TEXT 456 304 Left 0 ;3
TEXT 456 360 Left 0 ;4
TEXT 200 368 Left 0 ;5
TEXT 200 304 Left 0 ;6
TEXT 200 240 Left 0 ;7
TEXT 200 176 Left 0 ;8


I've just posted a query to:

 http://groups.yahoo.com/group/LTspice/

for clarification re. the accuracy of the model, and I'll post what
comes back as soon as I get it.

Maybe Helmut will post here first.

-- 
JF
Reply by Bitrex ●March 24, 20112011-03-24
On 3/24/2011 12:33 PM, Bitrex wrote:

> On 3/22/2011 7:01 PM, Jim Thompson wrote:
>> On Tue, 22 Mar 2011 17:01:45 -0500, John Fields
>> <jfields@austininstruments.com> wrote:
>>
>>> On Fri, 18 Mar 2011 22:46:48 -0400, Bitrex
>>> <bitrex@de.lete.earthlink.net> wrote:
>>>
>>>> On 3/18/2011 7:13 PM, Jim Thompson wrote:
>>>>> Got annoyed at the flaky 555 models that are out there, so I rolled my
>>>>> own...
>>>>>
>>>>> http://www.analog-innovations.com/SED/MyLMC555.zip
>>>>>
>>>>> Based on old AMI 20V CMOS device models, mostly form/fit/function with
>>>>> CMOS, but some behavioral on the front-end where it doesn't matter.
>>>>>
>>>>> Optimized and fitted to National LMC555 at 5V operation. It'll work
>>>>> at other voltages but may sink/source more or less than spec at other
>>>>> voltages because of ancient 5u devices :-)
>>>>>
>>>>> Try it out and let me know.
>>>>>
>>>>> ...Jim Thompson
>>>>
>>>> Hi Jim,
>>>>
>>>> Thanks for taking the time to create this model. I was doing some
>>>> experimenting with it and comparing it to the standard bipolar 555
>>>> model, and noticed that the CMOS model seems to have significantly
>>>> greater shoot-through current than the bipolar model. I haven't used a
>>>> CMOS 555 or measured those currents "in real life", so I'm curious if
>>>> that is a real difference, or perhaps the bipolar 555 models don't
>>>> model
>>>> it effectively?
>>>
>>> ---
>>> Notice that the shoot-through current for an ICM7555, in real life, as
>>> indicated on page 6 of:
>>>
>>> http://datasheets.maxim-ic.com/en/ds/ICM7555-ICM7556.pdf
>>>
>>> is very small compared to that from the bipolar 555, so there's either
>>> something wrong with Jim's model, or you're making an error of some
>>> kind.
>>>
>>> ---
>>> JF
>>
>> I sized my CMOS devices based on source and sink current of the output
>> at VCC=+5V for the _LMC555_ chip... Intersil datasheet was used only
>> for structural ideas.
>>
>> I simulate 7-8mA "shoot-thru" depending on direction of transition.
>> Which, for CMOS with considerable source sink capability, seems pretty
>> normal to me. Width at the 50% point of overlap current is 8.5ns,
>> TF/TR at output ~ 7.3ns
>>
>> What does "...significantly greater shoot-through current than the
>> bipolar model" mean?
>>
>> ...Jim Thompson
>
> Sorry for the delay in my reply, I didn't realize the thread was still
> active. Here's what I get using LTSpice with the test circuit:
>
> http://i227.photobucket.com/albums/dd240/bitrex2007/555.jpg
>
> The pulses appear to be about 100 ns wide. It probably is really better
> than the bipolar 555, because looking at the graph on the Maxim
> datasheet I don't believe the bipolar 555 model included with LTSpice is
> modeling the supply spikes accurately.


My mistake, I think the pulses are shorter than that.  It's a little 
tricky measuring them in LTSpice.
Reply by Bitrex ●March 24, 20112011-03-24
On 3/22/2011 7:01 PM, Jim Thompson wrote:

> On Tue, 22 Mar 2011 17:01:45 -0500, John Fields
> <jfields@austininstruments.com>  wrote:
>
>> On Fri, 18 Mar 2011 22:46:48 -0400, Bitrex
>> <bitrex@de.lete.earthlink.net>  wrote:
>>
>>> On 3/18/2011 7:13 PM, Jim Thompson wrote:
>>>> Got annoyed at the flaky 555 models that are out there, so I rolled my
>>>> own...
>>>>
>>>> http://www.analog-innovations.com/SED/MyLMC555.zip
>>>>
>>>> Based on old AMI 20V CMOS device models, mostly form/fit/function with
>>>> CMOS, but some behavioral on the front-end where it doesn't matter.
>>>>
>>>> Optimized and fitted to National LMC555 at 5V operation.  It'll work
>>>> at other voltages but may sink/source more or less than spec at other
>>>> voltages because of ancient 5u devices :-)
>>>>
>>>> Try it out and let me know.
>>>> 		
>>>>                                           ...Jim Thompson
>>>
>>> Hi Jim,
>>>
>>> Thanks for taking the time to create this model.  I was doing some
>>> experimenting with it and comparing it to the standard bipolar 555
>>> model, and noticed that the CMOS model seems to have significantly
>>> greater shoot-through current than the bipolar model.  I haven't used a
>>> CMOS 555 or measured those currents "in real life", so I'm curious if
>>> that is a real difference, or perhaps the bipolar 555 models don't model
>>> it effectively?
>>
>> ---
>> Notice that the shoot-through current for an ICM7555, in real life, as
>> indicated on page 6 of:
>>
>> http://datasheets.maxim-ic.com/en/ds/ICM7555-ICM7556.pdf
>>
>> is very small compared to that from the bipolar 555, so there's either
>> something wrong with Jim's model, or you're making an error of some
>> kind.
>>
>> ---
>> JF
>
> I sized my CMOS devices based on source and sink current of the output
> at VCC=+5V for the _LMC555_ chip... Intersil datasheet was used only
> for structural ideas.
>
> I simulate 7-8mA "shoot-thru" depending on direction of transition.
> Which, for CMOS with considerable source sink capability, seems pretty
> normal to me.  Width at the 50% point of overlap current is 8.5ns,
> TF/TR at output ~ 7.3ns
>
> What does "...significantly greater shoot-through current than the
> bipolar model" mean?
> 		
>                                          ...Jim Thompson


Sorry for the delay in my reply, I didn't realize the thread was still 
active.  Here's what I get using LTSpice with the test circuit:

http://i227.photobucket.com/albums/dd240/bitrex2007/555.jpg

The pulses appear to be about 100 ns wide.  It probably is really better 
than the bipolar 555, because looking at the graph on the Maxim 
datasheet I don't believe the bipolar 555 model included with LTSpice is 
modeling the supply spikes accurately.
Reply by John Larkin ●March 22, 20112011-03-22
On Tue, 22 Mar 2011 15:01:11 -0700, RST Engineering
<jweir43@gmail.com> wrote:


>
>About 5 years ago I did a design for a simple TRF receiver that used
>small Xicon (Mouser) tunable coils in the 50-200 nanohenry range, size
>10 mm and 7 mm series.
>
>Now they've gone to a minimum of 5000 pieces per value and by my
>calculations that will take me well into the next century at current
>use rates.
>
>Anybody got a good source for small tunable coils, preferably
>shielded?
>
>Thanks,
>
>Jim


Ask for samples!

John