On Sun, 26 Jan 2014 03:38:13 -0800, Fred Abse
wrote:
On Mon, 20 Jan 2014 15:12:52 -0700, Jim Thompson wrote:
On Mon, 20 Jan 2014 12:03:56 -0800, Fred Abse
wrote:
On Wed, 08 Jan 2014 16:39:56 -0700
Jim Thompson wrote:
Here is my first pass at the HC4046 (VCO portion only), now in LTspice
format...
http://www.analog-innovations.com/HC4046_VCO.zip
Looks pretty good to me, apart from LTspice not understanding "IS"
parameter.
Sometimes LTspice throws up over what it's supposed to know... IS is a
common parameter for MOS devices... defines the body diode.
LTspice doesn't seem to have a level 7 BSIM3.2, although it meekly accepts
"level=7", and digests all parameters, except Is.
Is *is* accepted in level 1 thru 3.
Frequency vs. Vc curves don't match datasheet curves, BTW, on further
playing. Using 300k/39pF, frequency range is low. Likewise 300k/0.1uF
3k/0.1uF shape not bad, but still low. 3k/39pF shape wrong.
(Comparison with ON Semiconductor 74HC4046 published data.)
Detailed plots when they churn out.
Yep, I haven't gone to the trouble (yet) of fitting the curves, but
I'm quite far along at breaking it into all behavioral. The
oscillator core is now all behavioral, but the logic is still device
level. (*)
The logic in my model is substantially faster than in the actual 4046,
which effects the frequency; plus the trip level, from the data sheet
is vague, but I should be able to extract that info from the different
curves. (And each brand data sheet is different ;-)
(*) Forcing me on a side trip... making behavioral logic that runs on
an analog simulator... e.g. crystal oscillators made with 'HCU04 will
simulate properly.
...Jim Thompson
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