Interesting that one is 0.35pF and the other 0.25pF, probably because of the not quite symmetrical pinout:
Both package variants non-stock at Digikey though :-(
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Try mouser if you want some.
I assume you would resist designing them in because you can't get them from digikey. I try to make it a rule never to spec a part that can't be bought from them with no lead time.
Coulomb's law is easily skirted: the collector swing is limited to about 280mV, or roughly 1/8th the supply in both oscillators, Jim's and mine. By design.
The dissipation arising from driving the 33pF timing cap is far more important at this hefty power level. (20uW is not low power.)
Ct sees about the same swing, but has a much higher capacitance. This burns power, but still comes in way under budget. And that was deliberate. I kept Ct high to minimize component sensitivities and the influence of strays.
If you wanted to save power you could cut Ct and raise impedances. Passive loads dissipate ~40% of this circuits' input power. Active loads would help, but add comlexity.
If we wanted to go to _really_ low powers then we'd want to recycle the energy pumped into the timing scheme elements
--like with an LC or crystal--rather than dumping it each time. That could save 80% of the power or more. Then better transistors would be useful, but not needed here.
So, again, 2n3904s are good enough.
But then there's the question of what exactly are you going to drive with this? A zero pF load? What accuaracy and stability are needed? Rise and fall times?
All silliness.
Cheers, James Arthur
They've got 37 parts. Not exactly a lot ...
Yep, same here. Some manufacturers understand that, some don't. Many of the ones that don't are relying on key account business and consequently are posting lots of quarterly losses. No surprise to me.
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That 33pF is going to spoil the broth when you need useful logic level amplitudes.
Yep, but adds a lot of complexity.
If you don't have to drive anything and just win a bet that you can make a 100kHz oscillator under 10uA, maybe.
That's why RF transistors may be needed. You may have to leave some headroom for the load capacitance. It ain't going to be zero.
Hard to say without knowing the purpose of this oscillator. Watch manufacturers certainly would not call their designs silly, the difference between a two-year battery lifetime and five years can be a strong sales argument ;-)
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Here's how I do it...
on my custom chip designs... downright trivial when you can size devices to suit ;-)
It is left as an exercise for the student to show that oscillation frequency is flat with supply variations all the way down to about
2*VT0....Jim Thompson
-- | James E.Thompson, P.E. | 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 | | | | Vote Barack... Help Make America an Obama-nation | | | | Due to excessive spam, googlegroups, UAR & AIOE are blocked! |
ow-
ws
I missed the part where we were designing a watch oscillator with a 5-year life, 100kHz +/- 5ppm 0-40=BAC. (If we wanted to do that the lower frequency makes 2n3904s sing even sweeter :-)
I thought we--Jim, John Fields and I--were just having some fun with a nonsense requirement. Yeah, I could do any and all of what you want, but that's not the assignment.
Wanna play? Post your favorite circuit.
Cheers, James Arthur
t,
ce
a fI always have at least enough parts for the prototypes in my desk=20 before the schematic is finalized. However, I'm not the one=20 controlling the BOM this time (the boards are now six months late). =20 :-(
--=20 Keith
The temp range won't do in watch apps. Just wanted to point out that such requirements are not always nonsense.
Maybe but first I'll have to crawl underneath the house some more. I finally fixed out little valve problem just to be replaced by a new problem: Water hammer. Darn!
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
On Jul 5, 4:26=A0am, James Arthur wrote:
, e aWith more nearly real components, plugged into the standard LTspice example astable you can get 1.5uA
Version 4 SHEET 1 2848 1240 WIRE -576 576 -736 576 WIRE -112 576 -576 576 WIRE -576 608 -576 576 WIRE -112 608 -112 576 WIRE -576 704 -576 688 WIRE -464 704 -576 704 WIRE -384 704 -464 704 WIRE -240 704 -320 704 WIRE -112 704 -112 688 WIRE -112 704 -240 704 WIRE -736 720 -736 576 WIRE -464 736 -464 704 WIRE -240 736 -240 704 WIRE -576 832 -576 704 WIRE -112 832 -112 704 WIRE -496 880 -512 880 WIRE -464 880 -464 816 WIRE -464 880 -496 880 WIRE -448 880 -464 880 WIRE -384 880 -320 704 WIRE -320 880 -384 704 WIRE -240 880 -240 816 WIRE -240 880 -256 880 WIRE -208 880 -240 880 WIRE -176 880 -208 880 WIRE -496 928 -496 880 WIRE -208 928 -208 880 WIRE -576 1008 -576 928 WIRE -496 1008 -496 992 WIRE -496 1008 -576 1008 WIRE -208 1008 -208 992 WIRE -112 1008 -112 928 WIRE -112 1008 -208 1008 WIRE -736 1040 -736 800 WIRE -576 1040 -576 1008 WIRE -112 1040 -112 1008 FLAG -112 1040 0 FLAG -576 1040 0 FLAG -736 1040 0 SYMBOL RES -592 592 R0 SYMATTR InstName R1 SYMATTR Value 5100K SYMBOL res -128 592 R0 SYMATTR InstName R2 SYMATTR Value 5100K SYMBOL cap -384 864 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C1 SYMATTR Value 3.3p SYMBOL cap -256 864 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C2 SYMATTR Value 3.3p SYMBOL VOLTAGE -736 704 R0 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL npn -176 832 R0 SYMATTR InstName Q1 SYMATTR Value BFR92A SYMBOL npn -512 832 M0 SYMATTR InstName Q2 SYMATTR Value BFR92A SYMBOL res -256 720 R0 SYMATTR InstName R3 SYMATTR Value 15000K SYMBOL res -480 720 R0 SYMATTR InstName R4 SYMATTR Value 15000.1K SYMBOL cap -512 928 R0 SYMATTR InstName C3 SYMATTR Value 3.3p SYMBOL cap -224 928 R0 SYMATTR InstName C4 SYMATTR Value 3.3p TEXT -768 1176 Left 0 !.tran 0 1.5m 0.5m startup TEXT -776 1224 Left 0 ;This example schematic is supplied for informational/educational purposes only. TEXT -480 1176 Left 0 !.model BFR92A NPN(IS=3D0.1213E-15 VAF=3D30 BF=3D94.7=
3 IKF=3D0.46227 XTB=3D0 BR=3D10.729 CJC=3D946.47E-15 CJE=3D10.416E-15 TR=3D1.2744E-9 TF=3D26.796E-12 ITF=3D0.0044601 VTF=3D0.32861 XTF=3D0.3817 RB=3D14.998 RC=3D0.13793 RE=3D0.29088 Vceo=3D15 Icrating=3D4m mfg=3DInfineo= n)-- Bill Sloman, Nijmegen
Ok, example:
3.3V 3.3V | | \\ \\ / 1M / \\ 1M \\ / / | | | | o-------o-------. '-------o-------o | | | 2.2p| | | | \\ --- --- \\ | | / --- --- / | | \\ 2M |2.2p | \\ 2M | | / | | / | | | | | | | \\| --------)---------' | |/ |-----' | -o-----| BFP620 | BFP620 |GND GND (created by AACircuit v1.28.6 beta 04/19/05
Forgive the lousy schematic, I am not used to these ASCII editors. Anyhow, 3.3V is beyond the BFP620's 2.3V limit but there are similar oens that reach there. Uses around 5uA in SPICE. Thing is, with a 2N3904 this won't work at all. It's capacitances snuff it out. Of course this is rather hokey in terms of stray capacitance and would need the usual "anti-RF" precautions such as ferrite beads or at least small resistors in front of the bases.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
Here's the same version, generated by a program I wrote directly from an LTSpice schematic. No need to work with an ASCII editor:
Note that everything I used is included. I could add comments and those would be included on the ASCII version, as well. Also, boxes and so on, too, if I'd used them to 'enhance' the schematic.
By the way, I used the PN5179 here, which is available and in stock at Mouser and costs 8 cents each if you only buy one at a time.
Jon
You automated creation of an ASCII schematic directly from LTspice??
How did you do that?
...Jim Thompson
-- | James E.Thompson, P.E. | 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 | | | | Obama-lackey! Obama-lackey! Boom! Boom! Boom! | | | | Obama-lackey Wesley Clark opines:"He (McCain) hasn\'t held exe- | | cutive responsibility. I don\'t think riding in a fighter plane| | and getting shot down is a qualification to be president." | | | | But being a small potatoes politician who\'s served only three | | years in the Senate does ??? | Due to excessive spam, gmail, googlegroups, UAR, AIOE are blocked!
On the off chance that you haven't seen one: they make water hammer arrestors. It's just an air chamber in a Tee off the water line. I used one that is a sphere, maybe the size of a grapefruit, but they usually (?) are cylindrical. Anyway, it was a perfect solution for me. You *might* not have to install one near the "offending" valve, possibly you could save yourself another crawl.
Ed
The program directly reads the .ASC schematic and uses an ASCII library of symbols. It handles rotated parts just fine, wires, etc. I am working on a newer version that will also go read up the graphic symbol file descriptions and, without the use of an ASCII library at all, automatically produce optical ASCII representations of the graphical images. I use a virtual ASCII tablet and some of the logic involved is... a bit involved. But it works darned well. For example, the BJT symbol file uses vector drawings but my routines can draw these onto the ASCII tablet and reproduce exactly what you would expect in ASCII, but entirely automatically and without any human intervention.
Jon
[snip]
What type name and where?
...Jim Thompson
-- | James E.Thompson, P.E. | 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
Due to excessive spam, gmail, googlegroups, UAR, AIOE are blocked!
Have you considered writing schematic conversion programs, say PSpice to Cadence Composer, or PSpice to SPE? I would pay real money for that ;-)
...Jim Thompson
-- | James E.Thompson, P.E. | 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 | | | | Obama-lackey! Obama-lackey! Boom! Boom! Boom! | | | | Obama-lackey Wesley Clark opines:"He (McCain) hasn\'t held exe- | | cutive responsibility. I don\'t think riding in a fighter plane| | and getting shot down is a qualification to be president." | | | | But being a small potatoes politician who\'s served only three | | years in the Senate does ??? | Due to excessive spam, gmail, googlegroups, UAR, AIOE are blocked!
Yes, they also make srping-types that don't lose the air pocket. But it'll be a crawl because of the long pipes. I am thinking about ripping the whole chebang out and doing it right. Sometimes I wonder what trade license are good for. Heck, they even screwed a brass valve into a brass tee using a steel nipple. #%^&*!!
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
They are made by Sioux Chief. You can either get or order them at a hardware store. Looks like this:
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
I don't have a professional need for schematic capture and simulation programs, not where either I or a client would pay for a license for me, anyway. So I've no experience with PSpice, Cadence Composer (somehow 'Composter' sprung to mind), or SPE and don't know what's involved. Don't they provide conversions, since these programs are competing for customers?
In any case, what I spent time doing was converting vector graphics and text to ASCII schematic art. I don't imagine the key technology in doing that (mostly figuring how to make reasoned human-perception choices of ASCII to represent vector drawings) is much value mapping one kind of schematic file to another kind. I suspect that is more a compiler that reads one kind of source to generate another. Easier in some ways, I imagine, but possibly complicated by realities I'm also not aware of.
Still, I'm not one to turn down a fast buck. ;)
Jon
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